arsenic and fl uoride contaminated groundwaters: a review of current technologies for contaminants...

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Review Arsenic and uoride contaminated groundwaters: A review of current technologies for contaminants removal Sachin V. Jadhav a , Eugenio Bringas b , Ganapati D. Yadav a, * , Virendra K. Rathod a , Inmaculada Ortiz b , Kumudini V. Marathe a a Department of Chemical Engineering, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai, 400019, India b Department of Chemical and Biomolecular Engineering, Universidad de Cantabria, Avda, Los Castros s/n. 39005, Santander, Spain article info Article history: Received 23 November 2014 Received in revised form 26 June 2015 Accepted 7 July 2015 Available online xxx Keywords: Fluoride Arsenic Membrane Adsorption Electrocoagulation Ion exchange, Contaminant removal abstract Chronic contamination of groundwaters by both arsenic (As) and uoride (F) is frequently observed around the world, which has severely affected millions of people. Fluoride and As are introduced into groundwaters by several sources such as watererock interactions, anthropogenic activities, and groundwater recharge. Coexistence of these pollutants can have adverse effects due to synergistic and/or antagonistic mechanisms leading to uncertain and complicated health effects, including cancer. Many developing countries are beset with the problem of F and As laden waters, with no affordable tech- nologies to provide clean water supply. The technologies available for the simultaneous removal are akin to chemical treatment, adsorption and membrane processes. However, the presence of competing ions such as phosphate, silicate, nitrate, chloride, carbonate, and sulfate affect the removal efciency. Highly efcient, low-cost and sustainable technology which could be used by rural populations is of utmost importance for simultaneous removal of both pollutants. This can be realized by using readily available low cost materials coupled with proper disposal units. Synthesis of inexpensive and highly selective nanoadsorbents or nanofunctionalized membranes is required along with encapsulation units to isolate the toxicant loaded materials to avoid their re-entry in aquifers. A vast number of reviews have been published periodically on removal of As or F alone. However, there is a dearth of literature on the simultaneous removal of both. This review critically analyzes this important issue and considers stra- tegies for their removal and safe disposal. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Water is not only an essential component for life but also a basic building block to maintain quality of life. Water scarcity has already revealed adverse effects on all populations in every continent. More recently, UNICEF and WHO reports have conrmed that 748 million people do not have adequate and safe water resource and over 2.5 billion people have access to meagre water supply. The WHO also estimates that 1.8 billion people use faecally contaminated source of drinking water (UNICEF/WHO, 2014). Groundwater is used for potable purposes by over 50% of the global population. Thus, groundwater is sometimes described as the hidden sea. This is indeed true to a greater extent in countries like India where local supply to ~80% rural and ~50% urban dwellings is provided by groundwater sources alone (Ayoob et al., 2008). Presence of several naturally occurring, anthropogenic and in- dustry generated ions such as uoride, arsenic, nitrate, sulfate, iron, manganese, chloride, selenium, heavy metals, and radioactive materials may greatly compromise water quality, leading to health problems. The most signicant inorganic pollutants in groundwater affecting human health at the global scale, according to the WHO, are arsenic and uoride (Thompson et al., 2007). In this context, uoride pollution of drinking water receives much less consider- ation than arsenic. 1.1. Health effects of single and combined As and F Fluoride is the only chemical in potable water that can cause Abbreviations: WHO, World Health Organization; USEPA, United States Envi- ronmental Protection Act; CPC, chemical precipitation/coagulation; EC, electro- coagulation; EF, electrocoagulation/otation; AD, adsorption; IE, ion exchange; MT, membrane technology; RO, reverse osmosis; FO, forward osmosis; NF, nano- ltration; ED, electrodialysis. * Corresponding author. E-mail addresses: [email protected], [email protected] (G.D. Yadav). Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman http://dx.doi.org/10.1016/j.jenvman.2015.07.020 0301-4797/© 2015 Elsevier Ltd. All rights reserved. Journal of Environmental Management 162 (2015) 306e325

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Page 1: Arsenic and fl uoride contaminated groundwaters: A review of current technologies for contaminants removal

lable at ScienceDirect

Journal of Environmental Management 162 (2015) 306e325

Contents lists avai

Journal of Environmental Management

journal homepage: www.elsevier .com/locate/ jenvman

Review

Arsenic and fluoride contaminated groundwaters: A review of currenttechnologies for contaminants removal

Sachin V. Jadhav a, Eugenio Bringas b, Ganapati D. Yadav a, *, Virendra K. Rathod a,Inmaculada Ortiz b, Kumudini V. Marathe a

a Department of Chemical Engineering, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga, Mumbai, 400019, Indiab Department of Chemical and Biomolecular Engineering, Universidad de Cantabria, Avda, Los Castros s/n. 39005, Santander, Spain

a r t i c l e i n f o

Article history:Received 23 November 2014Received in revised form26 June 2015Accepted 7 July 2015Available online xxx

Keywords:FluorideArsenicMembraneAdsorptionElectrocoagulationIon exchange, Contaminant removal

Abbreviations: WHO, World Health Organizationronmental Protection Act; CPC, chemical precipitatcoagulation; EF, electrocoagulation/flotation; AD, adsomembrane technology; RO, reverse osmosis; FO,filtration; ED, electrodialysis.* Corresponding author.

E-mail addresses: [email protected],(G.D. Yadav).

http://dx.doi.org/10.1016/j.jenvman.2015.07.0200301-4797/© 2015 Elsevier Ltd. All rights reserved.

a b s t r a c t

Chronic contamination of groundwaters by both arsenic (As) and fluoride (F) is frequently observedaround the world, which has severely affected millions of people. Fluoride and As are introduced intogroundwaters by several sources such as watererock interactions, anthropogenic activities, andgroundwater recharge. Coexistence of these pollutants can have adverse effects due to synergistic and/orantagonistic mechanisms leading to uncertain and complicated health effects, including cancer. Manydeveloping countries are beset with the problem of F and As laden waters, with no affordable tech-nologies to provide clean water supply. The technologies available for the simultaneous removal are akinto chemical treatment, adsorption and membrane processes. However, the presence of competing ionssuch as phosphate, silicate, nitrate, chloride, carbonate, and sulfate affect the removal efficiency. Highlyefficient, low-cost and sustainable technology which could be used by rural populations is of utmostimportance for simultaneous removal of both pollutants. This can be realized by using readily availablelow cost materials coupled with proper disposal units. Synthesis of inexpensive and highly selectivenanoadsorbents or nanofunctionalized membranes is required along with encapsulation units to isolatethe toxicant loaded materials to avoid their re-entry in aquifers. A vast number of reviews have beenpublished periodically on removal of As or F alone. However, there is a dearth of literature on thesimultaneous removal of both. This review critically analyzes this important issue and considers stra-tegies for their removal and safe disposal.

© 2015 Elsevier Ltd. All rights reserved.

1. Introduction

Water is not only an essential component for life but also a basicbuilding block tomaintain quality of life. Water scarcity has alreadyrevealed adverse effects on all populations in every continent. Morerecently, UNICEF andWHO reports have confirmed that 748 millionpeople do not have adequate and safe water resource and over 2.5billion people have access to meagre water supply. The WHO alsoestimates that 1.8 billion people use faecally contaminated sourceof drinking water (UNICEF/WHO, 2014). Groundwater is used for

; USEPA, United States Envi-ion/coagulation; EC, electro-rption; IE, ion exchange; MT,forward osmosis; NF, nano-

[email protected]

potable purposes by over 50% of the global population. Thus,groundwater is sometimes described as the ‘hidden sea’. This isindeed true to a greater extent in countries like India where localsupply to ~80% rural and ~50% urban dwellings is provided bygroundwater sources alone (Ayoob et al., 2008).

Presence of several naturally occurring, anthropogenic and in-dustry generated ions such as fluoride, arsenic, nitrate, sulfate, iron,manganese, chloride, selenium, heavy metals, and radioactivematerials may greatly compromise water quality, leading to healthproblems. Themost significant inorganic pollutants in groundwateraffecting human health at the global scale, according to the WHO,are arsenic and fluoride (Thompson et al., 2007). In this context,fluoride pollution of drinking water receives much less consider-ation than arsenic.

1.1. Health effects of single and combined As and F

Fluoride is the only chemical in potable water that can cause

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S.V. Jadhav et al. / Journal of Environmental Management 162 (2015) 306e325 307

different health effects depending upon its concentration in dis-solved form. A very small amount of fluoride is beneficial for boneand teeth development and dental health. However, concentrationshigher than 1.5 mg/L are damaging to human health, causing dentalor skeletal fluorosis (Miretzky and Cirelli, 2011). Children below 12years are likely to be most exposed to fluorosis as their body tissuescontinue to grow during the formative age. Moreover, fluorosis isnon-reversible and the disorder has no medical treatment. TheWHO permits a fluoride concentration of 0.5e1 mg/L in drinkingwater (WHO, 2011). Effluent limit of 4 mg/L for F from the waste-water treatment facilities has been set by USEPA (Shen et al., 2003).Fig. 1 depicts the statistics on population exposed to F contamina-tion. Clearly, China and India are the most affected countries wherenearly 35 and 26 million, respectively, people are at fluoride risk.

As for arsenic, As(V) (arsenate) and As(III) (arsenite) are themost predominant valence states, which are found in aerobic sur-face waters and anaerobic groundwaters, respectively. Between pH4 and 10, major As(III) compound is charge neutral, whereas As(V)species exists as charge negative. The occurrence of As in ground-water poses even a greater danger than F hazards due to its extremetoxicity at low concentration which goes undetected especially inAs(III) form (Camacho et al., 2011). Arsenic is well known for itscarcinogenicity in kidney, lung, liver, skin, and bladder. At highconcentrations, As causes gastrointestinal problems and arsen-icosis, which arise mainly via consumption of water containing Asand its subsequent accumulation in the body (Sharma and Sohn,2009; Villaescusa and Bollinger, 2008). Therefore, the WHO rec-ommends As concentration of 10 mg/L as the upper permissiblelimit in water (WHO, 2011). This limit is applicable in India, JapanTaiwan, USA and Vietnam (Hug et al., 2008; Reddy and Roth, 2013)while other countries like China, Bangladesh, and most of SouthAmerican nations have permitted a higher concentration of 50 mg/L(Camacho et al., 2011; Chakraborti et al., 2010). A report preparedby UNICEF consultant Ravenscroft (2007) estimates that natural Aspollution of groundwater and surface water affects more than 140million people in at least 70 countries worldwide. A large popula-tion of South Asia is exposed to As toxicity (Fig. 2).

When two different types of harmful contaminants are

Fig. 1. Estimated population exposed to F contamination in selected countries (�103) (C

ingested, they may function independently or synergistically orantagonistically to one another (Chouhan and Flora, 2010). Whilethe harmful effects of As and F individually have been widelystudied, the exposure to both together has received little atten-tion. Rao and Tiwari (2006) reported that As and F in combina-tion affect integrity of cells genetic material more than theindividual exposure. In animal studies for rats, co-exposure of Asand F even at low concentrations resulted in decreased comet tailand detrimental effect on liver and kidney (Flora et al., 2009;Mittal and Flora, 2006). Wang et al. (2007) reported that chil-dren's growth and intelligence were severely influenced by highconcentrations of As or F. Hence, it is important to remove thesetoxicants from potable water. Despite the extreme seriousness ofthe issue, very less data exist on the populations facing simul-taneous toxicity of As and F.

This article analyzes the genesis of the combined presence ofgeogenic fluoride and arsenic in groundwater and drinkingwater aswell as the treatment methods for their removal. Also, it reviewsthe effectiveness of several treatment methods when these twocontaminants are present together.

2. Occurrence of F and As in groundwaters

There is an evidence of the presence of fluoride in differentlatitudes such as south-east of Africa, United States, the Middle Eastof Asia, South America, and Asian countries. However, China andIndia are the worst affected countries (Fig. S-1, supplementaryinformation).

For past few decades, the areas with arid and semi-arid climatesare suffering from the scarcity of water due to the fact that theuptake of groundwater is in far excess than water recharge as wellas excessive evaporation leading to decreased availability of water(Jakariya et al., 2003, 2007). Since fluoride primarily originates fromfluoride rich rocks, concentrations of fluoride are directly propor-tional to the extent of leaching/dissolution of crystalline mineralsthrough watererock interactions. The sources of fluoride ingroundwater through fluoride-rich rocks are (i) flurospar (CaF2)from lime stones, sand stone, sedimentary rocks; (ii) cryolite

DC, 1993; Diaz-Barriga et al., 1997; Fewtrell et al., 2006). * no recent data available.

Page 3: Arsenic and fl uoride contaminated groundwaters: A review of current technologies for contaminants removal

Fig. 2. Estimated population exposed to As contamination in selected countries (�103) (Ravenscroft, 2007).

S.V. Jadhav et al. / Journal of Environmental Management 162 (2015) 306e325308

(Na3AlF6) from igneous rocks, granite; (iii) fluorapatite (Ca5(PO4)3F)from igneous rocks, metamorphic rocks, and (iv) sellaite (MgF2)from bituminous dolomiteeanhydrite rock.

Arsenic occurs in the environment in several oxidation states asstated earlier. Parsa and Shahidi (2010) stated that unusual largeproportions of As are present in potentially soluble forms. Studieshave shown that over exploitation of shallow (or main) aquifer hasbeen the source of many arsenic problems (Jakariya andBhattacharya, 2007). Fig. S-2 (supplementary information) showsthe identified regions of world having arsenic contamination ofgroundwaters. Very high concentrations of As can be seen pre-dominant in Mexico, USA, China, Bangladesh, Vietnam andPakistan. Recently, groundwaters in Japan and Korea were alsofound to be contaminated with As (Ahn, 2012; Yoshizuka et al.,2010). The major mechanism responsible for the As contamina-tion in groundwater is desorption from iron oxides or hydroxidesfrom natural rocks and their reductive dissolution (Kim et al., 2012;Li et al., 2012).

Fig. S-3 (supplementary information) shows the co-occurrenceof fluoride and arsenic worldwide. Arsenic and F are found to co-exist in groundwaters in China, Argentina, Mexico, and Pakistanamong other countries where As concentrations up to 5300 mg/Land F up to 29 mg/L are noticed in the same groundwaters (Jinget al., 2012). Recently, Australia, Japan, Korea, and Chile have alsobeen shownwith elevated levels of As and F co-occurrence (Fig. S-3,supplementary information) (Ahn, 2012; Chakraborti et al., 2011;Fernandez-Turiel et al., 2005; Richards et al., 2009; Yoshizukaet al., 2010). Table S-1 (supplementary information) presentsdetailed information on As and F co-contamination in groundwa-ters with respect to geographical location and lists key findings ofvarious publications.

Arsenic is found to be frequently associated with fluoride inshallow aquifers around the world. A high concentration of As isalso found in semi-arid regions that contain oxidized groundwater(Currell et al., 2011). The correlations between these two toxicantsare dissimilar as per redox potential (Kim et al., 2012). The Fe-hydroxides adsorption capacity of F and As decreases with in-crease in pH, releasing both components into groundwater indi-cating that the Fe-(hydr)oxides play an important role for hostingthe co-contamination (Streat et al., 2008). High concentrations of

As (10e5300 mg/L) and F (51e7340 mg/L) are reported in shallowgroundwaters, indicating potential risk of arsenicosis and fluorosisin Chaco-Pampean plain of Argentina where As and F borne dis-eases affect ~2e8 million people (Nicolli et al., 2012). The concur-rent presence of As and F in groundwater is connected to volcaniceruptions, geothermal currents and mining activities (Alarcon-Herrera et al., 2013).

Selected data on As and F levels inwaters from around theworldare presented in Table 1. Excessive rates of evaporation in arid andsemi-arid regions lead to generation of saline groundwaters andalkaline pH, which are related to high concentrations of As and F ingroundwater (Nicolli et al., 2008a, 2008b). Presence of Naþ andHCO3

� are also correlated with simultaneous presence of highconcentrations of As and F. On the other hand, studies in YunchengBasin, northern China, have found amoderately positive correlationbetween pH and As and F concentrations indicating that high pHmay favor desorption of F and As, while HCO3

� may act as a sorptioncompetitor (Currell et al., 2011). These authors also have found astrong correlation between As and F, suggesting that the enrich-ment of As and F is governed by a common mechanism and/or dueto a set of aquifer conditions.

The sediment geochemical data of 2046 samples from northernMexico were generated by Alarcon-Herrera et al. (2013). The regionis surrounded by large basins filled with alluvium, and dominatedby a large number of wells. A strong correlation between As and Fwas observed in these localities where As has been reported in highamounts indicating co-occurrences of As and F. Nicolli et al. (2008b)have found a strong link between F and As concentration in deepwells in Cordoba province, Argentina.

3. Methodologies for toxicant removal from groundwaters

3.1. Fluoride removal

Basically, defluoridation of water can be introduced at twoorganizational levels; as household defluoridation, carried out byindividual households for their own water consumption, and ascommunity defluoridation, carried out at village, town, sub-urbanarea levels. As it has been previously reported in the reviews ofAyoob et al. (2008) and Mohapatra et al. (2009), many technologies

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Table 1Data on groundwaters containing As and F.

Parameter Geographical location

Zhijiliang, InnerMongolia, China

Meoqui City,Chihuahua,Mexico2 sites

Kalalanwala andKot Asadullah,Pakistan2 depths

Un-known site,India

Kyushu, Japan16 sites

Chihuahua,Mexico

GeumsanCounty,KoreaMin. andMax.

Santiago del EsteroProvince, Argentina

pH 7.57 7.2 7.4 8 7.55 7.2 2.8-8.5 7.17 5.78 8.68 6.4-9.3Temperature, �C 13 e e 25 ± 2 25 ± 2 20.5 e 25 12 23 e

Arsenic, mg/L 1.10 0.134 0.075 0.235 0.06 0.13 0.01e3.23 0.435 e 113 0.01-15Fluoride, mg/L 1.59 5.9 4.8 11 1.47 5 0.04e3.76 11.8 e 7.54 0.7-22Sodium, mg/L 119 e e 630 273 e 1.1e1501 250 1.64 66.8 e

Carbonate, mg/L 10 121 126 857 410 e e e 8.64 239 e

Turbidity, NTU 311 1.4 1.1 e e 320 e 1 e e e

Hardness, mg/L 51.5 24.5 58.3 e e e e e e e e

Reference Zhang et al. Pinon-Miramonteset al.

Farooqui et al. Devi et al. Yoshizuka et al. Nevarez et al. Ahn Bhattacharya et al.

Year 2003 2003 2007 2008 2010 2011 2012 2006

S.V. Jadhav et al. / Journal of Environmental Management 162 (2015) 306e325 309

have been employed and are currently being used to carry out the Fremoval from potable water such as ion exchange (Chubar, 2011),adsorption (Bhatnagar et al., 2011; Gong et al., 2012a), coagulationand electrocoagulation (Behbahani et al., 2011; Gong et al., 2012b),and membrane processes (Richards et al., 2010). Each of thesetechnologies has its own merits and demerits. Fig. 3 presents atypical initial concentration range treatable by a particular tech-nology and its corresponding removal efficiency. It can be seen thatchemical treatment is capable of treating very high concentrationsof F; since it cannot bring F concentration within WHO permissiblelimit, it can be coupled with other technologies as a primarytreatment method (Islam and Patel, 2007). This approach offersadvantage of better life expectancy of secondary or tertiary treat-ment due to reduced load.

3.1.1. Chemical precipitation/coagulation (CPC)The roots of the defluoridation processes can be traced to the

early 1930's since when researchers from all around the world have

Fig. 3. Fluoride removal performance of various technologies. Where, CPC-11 ¼ Reardon andEC/EF-14 ¼ Bennajah et al. (2009); EC-15 ¼ Khatibikamal et al. (2010); AD-16 ¼ Cengeloglu e19 ¼ Thakre et al. (2010); AD-110 ¼ Ganvir and Das (2011); IE-111 ¼ Solangi et al. (2009); IE(2000); RO-114, NF-114 ¼ Dolar et al. (2011); ED-115 ¼ Zeni et al. (2005); ED-116 ¼ Ergun

been trying to develop a sustainable cost effective technology toreduce F concentrations in water. CSIR-NEERI in Nagpur, India,developed the Nalgonda process for the defluoridation of drinkingwater. The technique has been operated in a number of villages inIndia as fill and draw type and hand-pump attached plants(Meenakshi and Maheshwari, 2006).

Chemical precipitation technique involves addition ofaluminum salts along with lime to the F rich water followed byflocculation and sedimentation or filtration. In the first step, limereacts with F impurities such as NaF, HF, etc. to form insolublecalcium fluoride.

Ca(OH)2 þ 2F�/CaF2 þ 2OH� (1)

Ca(OH)2 (aq) þ 2NaF (aq) / CaF2 (s) þ 2NaOH (aq) (2)

Essentially, in the second step, aluminum sulfate or aluminumchloride or both together, is added. Aluminum salt acts as a

Wang (2000); CPC þ AD-12 ¼ Islam and Patel (2007); EC þ EF-13 ¼ Zuo et al. (2008);t al. (2002); AD-17 ¼ Tripathy et al. (2006); AD-18 ¼ Tripathy and Raichur (2008); AD--112 ¼ Viswanathan and Meenakshi (2009); RO-113, NF-113 ¼ Kettunen and Keskitaloet al. (2008).

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S.V. Jadhav et al. / Journal of Environmental Management 162 (2015) 306e325310

coagulant and is often being used for viable and effective F removalfrom water. The basicity present in water with alum yields analuminum salt, [Al(OH)3], which is insoluble.

It has been reported that the pH of the contaminated waterincreases up to 12; however, the best F removal is achieved be-tween the pH range of 6e7 (Aoudj et al., 2012). The dose of alum istypically around 20 fold the lime required. The fluoride fromgroundwater can be removed upto 96% from the initial concen-tration of 109 mg/L using lime (Reardon and Wang, 2000). Similarfindings on F removal by calcium salts have been confirmed byJadhav et al. (2014).

The Nalgonda technique has the advantages of low initial costand effectiveness. However, Nalgonda technique is not recom-mended owing to high maintenance cost, unpleasant water taste,requirement of large area for sludge drying, and a very high residualaluminum (Liu et al., 2013). The residual aluminum in watersranges from 2.01 to 6.86 mg/L under different operating conditions.Any amount over 0.2mg/L of aluminum in drinkingwater can causeserious health problems, including dementia (Shrivastava and Vani,2009).

3.1.1.1. Electrocoagulation (EC) and electrocoagulation/flotation (EF)Passage of an electric current into an aqueous medium helps to

destabilize suspended, dissolved and emulsified impurities, and theprocess is known as electrocoagulation (EC). During the pastdecade, the use of electrocoagulation (EC) as well as electro-coagulation/flotation (EF) process is on the rise. It can be effectivelyemployed to treat oily wastewaters, dye and textile industry ef-fluents and removal of organic matter, heavy metals and fluoride(Hu et al., 2003, 2005). EC is advantageous since no impurities areintroduced and useful contents existing in raw water can beretained during defluoridation.

Electrochemical cell (also known as “electrolytic cell”) is thebasis of electrocoagulation and electroflotation techniques. Anelectrocoagulation reactor typically consists of an electrolytic cellwith an anode and a cathode. Passage of the electric current leadsto the deterioration of the anode and cathode which may be madeof the same or different materials and which act as ‘sacrificialelectrodes’ (Mollah et al., 2001). It is reported that the followingthree routes are adapted for the electrocoagulation/flotation tech-niques, namely, (i) electrode oxidation, (ii) generation of gas bub-ble, (iii) flotation and sedimentation of flocs (Emamjomeh andSivakumar, 2009).

Electrocoagulation deals with electrochemical production ofdestabilization agents that lead to neutralization of electric chargeto remove pollutants. Charged particles coagulate together to makea mass. Effective removal of pollutants by flotation and sedimen-tation is augmented by metal based coagulants having a similareffect as themetal cations produced by anode. The key reactions areas follows (Zuo et al., 2008):

Al / Al3þ þ 3e at the anode (3)

Al3þ þ 3H2O / Al(OH)3 þ 3Hþ (4)

Al(OH)3 þ xF� / Al(OH)3�xFx þ xOH� (5)

2H2O þ 2e / H2 þ 2OH� at the cathode (6)

Evolution of hydrogen bubbles at the cathode improves the Fion mass transfer rates and also leads to floating of the aluminumcomplex (Al(OH)3�xFx) flocs at the top of the electrocoagulationsystem. Effective F removal can be achieved by isolating thealuminum complex from the aqueous phase periodically. There-fore, formation of aluminum complex [Al(OH)3�xFx] results in the

defluoridation of the source waters. Developments during thepast decade have demonstrated that EC is an effective techniquefor F removal in drinking waters and industrial wastewaters(Abuzaid et al., 2002; Essadki et al., 2009; Han and Kwon, 2002;Holt et al., 2002; Khatibikamal et al., 2010; Mameri et al., 2001).It has been reported that by using EC, fluoride concentrationscould be reduced to values lower than 1.5 mg/L from initial con-centrations ranging from 10 to 20 mg/L (Bennajah et al., 2009).Another advantage is that EC processes are characterized by loweramount of sludge and absence of chemical handling. However,electricity is required to operate the plant which increases itsoperating cost.

3.1.2. Adsorption (AD)Amongst other methods, adsorption (AD) is a conventional

technique which is widely used for defluoridation of water becauseit is economical, robust, environmentally benign and efficient. Newadvanced materials have been developed recently for effective andcheap fluoride removal from potable water. Many low cost adsor-bents have also been employed for fluoride removal like alumina,red mud, clays, soils, activated carbon, calcite, brick powder, acti-vated coconut-shell, activated kaolinites, oxides ores, modifiedchitosan, bone char, and some other low cost materials (Mohapatraet al., 2009).

A common mechanism by which the adsorption of F ionsoccurs onto solid particles can be given by the following threesteps: (i) mass transfer of F ions to the external surface ofthe adsorbent, (ii) F ion adsorption onto external particle surface,and (iii) intra-particle diffusion of F ions from the exterior surfaceand possible exchange with elements on the pore surfaceinside particles (Fan et al., 2003). Activated alumina happens tobe one of the most popular and widely used solid adsorbentsfor the defluoridation of potable water and many reports areavailable on large-scale installations (Chauhan et al., 2007).Alumina is popular amongst other adsorbents because it main-tains its structural stability without shrinkage, swelling ordisintegration in water (Serbezov et al., 2011). Granules of acti-vated alumina having a very high surface area of ~200e300 m2/gpossess a substantial number of active sites to facilitate adsorp-tion. At first, the acidification of alumina is carried out with HClas follows:

Alumina¤ H2O þ HCl / Alumina¤ HCl þ H2O (7)

(¤ represents activated state)The acidic alumina on contact with F ions displaces the Cl ions

and gets bonded to alumina.

Alumina¤HCl þ NaF / Alumina¤HF þ NaCl (8)

Further, regeneration is carried out by first treating the adsor-bent with alkaline solution followed by acid wash. A few reportsmention that F removal is due to ion-exchange as well as adsorp-tion following both Freundlich and Langmuir isotherms (Bansiwalet al., 2010; Ghorai and Pant, 2005).

Meenakshi and Maheshwari (2006) have reported the devel-opment of domestic and hand-pump units with activated aluminafor defluoridation. The unit consists of ~20 L capacity bucket, fittedwith a micro-filter at the bottom containing 5 kg of activatedalumina. Activated alumina coated with manganese dioxide wasfound to reduce F concentration to 0.2 mg/L from 10 mg/L at pH 5.5(Tripathy and Raichur, 2008). Magnesia-modified activatedalumina granules were also used successfully to reduce F fromdrinking water with a maximum adsorption capacity of 10.12 mg/gat F concentration of about 150 mg/L (Maliyekkal et al., 2008).

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S.V. Jadhav et al. / Journal of Environmental Management 162 (2015) 306e325 311

Biswas et al. (2009) characterized the synthetic hydrated iron (III)etin(IV) mixed oxide (HITMO) for F removal. It was found that the Fadsorption capacity decreased with increasing initial pH from 3.0 to5.0, and it remained constant up to pH of 7.5. Also, the high bicar-bonate content showed adverse effects on F removal by HITMO. Itwas the pseudo-second order kinetics with multiple-stage whichdefined rate-limiting step. The equilibrium data was best portrayedby Langmuir isotherm model with adsorption capacity 10.50 mg/gand adsorption energy ~9 kJ/mol. The fluoride-rich material wassuccessfully regenerated up to 75% in desorption studies.

All in all, the choice of the adsorbent seems to be reliant onfactors such as the ability to adsorb from dilute solutions, pH,removal duration, adsorbent stability, regeneration, and adsorptioncapacity in the presence of competing ions, and the economics(Mohapatra et al., 2009). The main disadvantage of the adsorptionprocess is that the adsorbent gets exhausted soon and considerabletime is required for regeneration. Moreover, regeneration stepsleads to secondary pollution because F containing aqueous solutionis discarded as a waste.

3.1.3. Ion exchange (IE)Many reports have highlighted the efficacy of ion exchange with

other techniques (Onyango et al., 2005, 2006). Usually, ion ex-change technique removes F by adsorption rather than exchangingions. The fundamental reason is that the fluoride concentration iscomparably lower than other ions present in water. Cation ex-change resins are more selective for F removal than anion exchangeresins (Meenakshi and Viswanathan, 2007). However, thedefluoridation capacity and selectivity for F is dependent on thetype of resin. The loading of metal ions influences the fluorideremoval drastically, owing to variations in their properties (Luo andInoue, 2004). Thus, it is difficult to maximize the defluoridationcapacity (DC) of ion exchange resins while simultaneouslyenhancing the F selectivity.

Viswanathan and Meenakshi (2008) used a widely available ionexchanger Indion FR 10 that has considerable F removal capabil-ities. It was chemically altered with Ce3þ, Fe3þ, La3þ, and Zr4þ

species to understand their selectivity for defluoridation. Themaximum defluoridation capacity of all the modified resins wasmeasured around 0.5 mg/g. The authors pointed out that thedefluoridation was due to electrostatic adsorption and complexa-tion. Recently, they have modified Indion FR 10 into Naþ and Al3þ

types by loading the metal ions in Hþ type of resin (Viswanathanand Meenakshi, 2009).

Chubar et al. (2005) obtained a new ion exchanger from doublehydrous oxide (Fe2O3$Al2O3$xH2O) by the solegel method fromeasily available raw materials, which was used for adsorption of F�,Cl�, Br�, and BrO3

� simultaneously. It was found that the pH effect ofF� and Br� was dependent on ion speciation. Sufficient capacity forsorption of all these anions was in the pH range of 3e10. The Fadsorption of 88 mg/g was the highest among all species. Solangiet al. (2009) modified anionic resin Amberlite XAD-4™, in whichthe amino group is introduced to the aromatic ring of the resin andutilized effectively for F extraction. They found that the modifiedresin was efficient particularly at pH 9 and was also effective in thepresence of other anions such as Br�, NO2

�, NO3�, HCO3

� and SO42�.

Subsequently, the authors modified Amberlite XAD-4™ resin byadding thio-urea binding sites into the aromatic rings (Solangiet al., 2010). The modified resin had high efficiency for F removalfrom aqueous solution at a wide range of pH from 4 to 10. The resincould be regenerated several times and used as an ion exchangematerial in filters for F removal from potable water.

Ion exchange treatment has a great F removal potential (up to95%). However, the resins are costly , thereby making the entire ionexchange method expensive. Regenerating the resins is simple but

it generates a large volume of F loaded waste which again is aproblem.

3.1.4. Membrane technology (MT)In recent years, membrane-based techniques have got a lot of

attention due to their performance and reliability in operation forthe removal of F from groundwater. At present, nanofiltration (NF),reverse osmosis (RO), and electro-dialysis (ED) are the most pop-ular membrane processes for F removal.

3.1.4.1. Reverse osmosis (RO) and nanofiltration (NF)In membrane filtration, thewater containing high concentration

of pollutants is passed through a semipermeable membrane. Themembrane discards atoms on the criteria of size and electric charge.The pollutants are removed from the water and collected atretentate side; whereas, clean water is recovered throughpermeate. In RO, pressure greater than the natural osmotic pressureis applied to the concentrated side of the membrane. Kettunen andKeskitalo (2000) evaluated the performance of a low energy ROmembrane with a NF membrane. A membrane filtration plant of16e25 m3/h capacity was constructed in Laitila, Finland, to controlF and Al concentration in drinking water. The comparative removalwas above 95 and 76% for F and Al, respectively and RO needed~1.6 bar excess feed pressure than that used in NF. Sehn (2008)studied a large scale RO plant in southern Finland for three years.The system was operated at a pressure of 6e11 atm and tempera-ture range of 5e11 �C, which was until recently possible only withNF membrane. This resulted in low power requirements and theplant was operated at 80% recovery without using a scaling inhib-itor. Richards et al. (2011) used four commercial NF/RO membranesin Australian groundwaters. Their investigations showed the in-fluence of solar irradiance levels on retention of F, Mg, NO3, K andNa where convection/diffusion predominated the retention. About85% of all solutes were retained during solar irradiance conditions.

Nanofiltration (NF) is a relatively new process in contrast to RO,ultrafiltration (UF) and microfiltration (MF), and it is emerging as apractically functional technology in treating industrial wastewa-ters. Nanofiltration is characterized by attributes between reverseosmosis (RO) and ultrafiltration (UF). Regardless of the similarity inoperation with RO, NF is operated at a comparatively lower pres-sure yielding identical permeate flux even at lesser pressure. NFremoves less than 60% of the monovalent ions as opposed to 90% byRO membranes. RO can completely demineralize water with verylow or practically no selectivity for monovalent ions but it suffersfrom high operating pressure, low permeate flux and high energyrequirements (Alarcon-Herrera et al., 2013). In particular, fractionaldefluoridation can be attained by altering the operating variables ofthe NF process; while simultaneously keeping the required F con-tent in the water.

Two of the popular NF membranes, NF90 and NF400, were usedto practically remove F from groundwaters (Tahaikt et al., 2007).The quality of water achieved by the NF400 membrane was foundto be satisfactory especially for lower F content. For higher F con-tent, a double pass was required to reduce it to an acceptable level.Further, these authors calculated the economics of a 100 m3/h NFplant corresponding to a recovery rate of 84%, F removal of 97.8%and pressure of 10 bar (Elazhar et al., 2009). The capital cost wasestimated to be 748,000 V with operating cost of 0.212 V per m3.Hu and Dickson (2006) investigated performance of negatively-charged commercial thin-film composite (TFC) nanofiltrationmembranes. They confirmed that higher pressures exhibit sub-stantial positive effect on F removal along with increase in the flux.

Malaisamy et al. (2011) modified a commercially available NFmembrane by layer-by-layer assembly of alternating poly-electrolyte thin films in order to promote removal and selectivity

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towards monovalent ions, particularly F and Cl. Polystyrene sulfo-nate (PSS) was the anionic polyelectrolyte and polydiallyldimethylammonium chloride (PDADMAC) was the cationic polyelectrolyte.Thin (0.5e8.5 mm) PDADMAC/PSS bilayers were deposited on thesubstrate membrane. The F ion removal increased from 40% (un-modified) to 70% (8-bilayer modified). These authors found that theselectivity for Cl over F was 2.7 times for an 8-bilayer modifiedmembrane compared to 1 for unmodified membrane.

3.1.4.2. Electrodialysis (ED)Electrodialysis is another emerging technique for removing

ionic compounds from aqueous media using ion exchange mem-branes in which the applied electric field acts as a driving force andis responsible for separation of contaminants. The application ofelectric current between two electrodes results in passage of cat-ions to the cathode and anions to the anode through the negativelycharged cation exchange membrane and positively charged anionexchange membrane, respectively. The end result is the increasedand decreased concentration of cations and anions in alternatepartitions. The global trend is shifting towards electrodialysis as analternate technique for defluoridation primarily because of itssimplicity and ability to overcome the shortcomings of the chem-ical processes.

Zeni et al. (2005) examined two ion-exchange membranes,namely, selenium AMP® anionic membrane and photo-polymericanionic membrane (MZA™) for electrodialysis. The AMP® mem-brane removed 69% and 97% F when the applied current densitywas 0.1 and 0.7 A/dm2, respectively whereas the MZA™membraneremoved 40% F without pretreatments. Ergun et al. (2008) reportedthat electrodialysis is the best method for F removal wherein anionexchange membrane SB-6407 was used and found that increasingcurrent density and feed concentration at pH 6 was the mosteffective. The presence of Cl and SO4 ions in the feed decreased theF removal efficiency. The F ion concentration could be broughtdown by 96% (0.8 mg/L), which is below the prescribed limit byWHO. Sahli et al. (2007) also suggested that electrodialysis givesbetter performance for the removal of Cl and F from brackish water.The combination of adsorption and electrodialysis appears to be acost-effective and better method to remove F ions from brackishgroundwater.

The most predominant advantages offered by membrane pro-cesses are: very high removal capacity (up to 98%), one step puri-fication and disinfection, and no chemical usage. However, it is notentirely appropriate as it removes all ions from the water. A remi-neralization process is required after the treatment as some min-erals are essential and must be present in potable water. Moreover,it is costly due to high initial membrane cost and operating cost.Also, disposal of concentrated F sludge which is produced atretentate side can be a major problem.

3.2. Arsenic removal

The most commonly used As removal methods are also essen-tially the same as those for F removal, namely, chemical treatment,adsorption onto sorptive media, co-precipitation and adsorptiononto coagulated flocs, ion exchange resin andmembrane processes.Rahman et al. (2014) discuss a different approach from the con-ventional methods and advocate utilizing exclusively bio-organisms for As reduction. An assessment of the removal effi-ciency of each of these can be seen in Fig. 4 along with the initial Asconcentration. Fig. 4 suggests that the overall treatable As con-centration ranges from 50 to 1000 mg/L. However, some researchershave successfully treated very high initial concentrations of As(5000e3,00,000 mg/L) (An et al., 2011; Robins et al., 2005; Songet al., 2006).

3.2.1. Chemical precipitation/coagulation (CPC)Arsenic can be removed most commonly by precipitation as

ferric arsenate, calcium arsenate or arsenic sulfide. The idealoperating pH for calcium generated precipitation is 10.5. Thoughthe reported attainable As concentration is 10 mg/L, usually theconcentrations below 1 mg/L are challenging to accomplish(Robins, 2006). Additionally, As(III) removal during coagulation isconsiderably less effective than As(V) under otherwise similarconditions and pre-oxidation is required by using an oxidizingagent such as Cl2, NaOCl, or H2O2 to convert As(III) to As(V). It is alsoevident that As precipitation with ferric salts is more efficient thanalum (Mohan and Pittman, 2007). Ferric salts are added to Ascontaminated water to form ferric arsenate (Holl, 2010):

Fe3þ þ AsO�43 /FeAsO4ðsÞ (9)

The efficacy of aluminum-based coagulationwas examinedwithreference to variable forms and As concentrations in three potablewater treatment plants in New Zealand (Gregor, 2001). SolubleAs(V), in general, was transformed to particulate As(V) by adsorp-tion during fast mixing, and eventually was removed by clarifica-tion along with natural As. The soluble As(III) was oxidized duringfinal chlorination, to soluble As(V). Baskan and Pala (2010)conclusively stated that aluminum sulfate is a very efficient coag-ulant at optimum pH of 6e8. The As removal efficiency was foundto be higher than 85%. Song et al. (2006) studied coagulation withFe3þ and coarse calcite, followed by normal filtration to achieveover 99% removal of As from a high-As water in mine drainage(5 mg/L As). However, filtration was essential after precipitation. Inthe absence of filtration, the As reduction was only ~30%, but with0.1 or 1.0 mm filter, the reduction exceeded 96% (Litter et al., 2010).

The Stevens Institute of Technology introduced a two bucketstechnology. The setup consists of a mixing bucket (of iron sulfateand calcium hypochloride) and a flocs separation bucket to achievesedimentation and filtration. The institute claimed to reduce Ascontent to less than 0.05 mg/L in 80e95% cases (Akter and Ali,2011). The Bangladesh Council of Scientific and IndustrialResearch (BCSIR) has introduced As removal technology by usingcoagulation process followed by sand filtration involving fill anddraw type units. The Bucket Treatment Unit (BTU) also uses twobuckets of 20 L capacity and is based on themethods of coagulation,co-precipitation and adsorption processes (Ahmed, 2001). It canremove As in nearly 2e3 h by this method. This technology issimple with low installation cost and only common chemicals areused such as aluminum sulfate and potassium permanganate.Moreover, it is possible to easily apply this technology to hugewater volumes to serve large communities.

On the other hand, like F, As can also be separated by electro-coagulation method. The mechanism of electrocoagulation is wasalready presented in section 3.1.1.1. Here the process can oxidizemore harmful and not so easily removable As(III) to less harmfuland easy to remove As(V) by virtue of electric current. Wan et al.(2011) carried out batch experiments using iron electrode to eval-uate the effect of various parameters on As removal. Faster removalof As(V) was achieved as compared to As(III) with over 99.9% overallAs removal efficiency. The authors also pointed out that the Asremoval was influenced by the presence of phosphate, while sulfateand silica did not show any significant effect. Studies by Kobya et al.(2011) have shown the effectiveness of electrocoagulation bylowering the As level to less than 10 mg/L. Arsenic removal wasobserved to be slightly better in case of Al electrode (95.7%) ascompared to Fe electrode (93.5%). The calculated operational costfor Fe and Al electrodes was 0.020 V per m3 and 0.017 V per m3,respectively. Similar results for the As removal have been reportedelsewhere (Balasubramanian et al., 2009; Kumar and Goel, 2010).

Page 8: Arsenic and fl uoride contaminated groundwaters: A review of current technologies for contaminants removal

Fig. 4. Arsenic removal performance of various technologies. Where, CPC-21 ¼ Baskan and Pala (2010); CPC-22 ¼ Oehmen et al. (2011); EC-23 ¼ Wan et al. (2011); EC-24 ¼ Kobyaet al. (2011) ¼ AD-25 ¼ Tubic et al. (2010); AD-26 ¼ Chatterjee (2007); AD-27 ¼Maji et al. (2008); AD-28 ¼ Amin et al. (2006); AD-29 ¼ Rahman et al. (2004); AD-210 ¼ Kundu et al.(2004); IE-211 ¼ Anirudhan et al. (2007); IE-212 ¼ Barakat and Shah (2013); IE-213 ¼ Urbano et al. (2012); IE þ RO-214 ¼ Oehmen et al. (2011); RO-215 ¼ Teychene et al. (2013); FO-216 ¼Mondal et al. (2014); NF-217 ¼ Floch and Hideg (2004); NF-218 ¼ Saitua et al. (2005); NF-219 ¼ Harisha et al. (2010). Note: Some treatment methods with greater removal arenot shown in the figure due to their very high initial concentration range between 5000 and 300000 mg As/L (An et al., 2011; Robins et al., 2005; Song et al., 2006).

S.V. Jadhav et al. / Journal of Environmental Management 162 (2015) 306e325 313

Coagulation can remove up to 99% of the As (Choong et al.,2007). Working at pH 3e4 reduces sludge generation. However,the quantity of iron required for equivalent As removal also in-creases (Camacho et al., 2011). By using this technique, a relativelylarge volume of As laden sludge is formed, which is normallydisposed of to landfills, which is a probable source of furthercontamination (Litter et al., 2010).

3.2.2. Adsorption (AD)As per USEPA classification, activated alumina, and in turn

adsorption, is amongst the best available technologies for Asremoval in potable water (Dambies, 2005). Activated carbon hasalso been extensively studied for the removal of As and F in water.Arsenic adsorption by activated carbon is explored in detail by anumber of researchers (Chuang et al., 2005; Gu et al., 2005). Ac-cording to the review published by Giles et al. (2011) the mainadsorbents of choice for As removal are Al2O3, Al(OH)3, carbon, FeO,Fe2O3, modified iron oxides, SiO2, layered double hydroxides (LDH),and organic polymers either as adsorbents per se or as supports. Abroad overview of adsorbents for As removal from drinking waterhas also been published by Yadanaparthi et al. (2009).

Hydrous metal oxide particles are useful for adsorption andform the hydroxyl groups in aqueous solutions leading to proteo-lytic reactions. The surface of such particles is at pH values belowthe zero charge point and the surface gets protonated and thusadsorbs anions. This can be expressed as (Holl, 2010),

>Me� OHþ Hþ / >Me� OHþ2 (10)

>Me� OHþ2 þ An�/>Me� OH2An (11)

where, Me ¼ trivalent metal atom on surface and Ane ¼ anions.A nano-sized Fe(OH)3 (~5 nm) offers a relatively large surface

area (200e500 m2/g), which is particularly useful for adsorbing avariety of anions and cations from waters (Gilbert et al., 2009;Pinney et al., 2009; Yavuz et al., 2006). As(V) adsorption isstrongly dependent on hydrous Fe(III) oxide concentration and pH,

whereas As(III) adsorption is independent of pH (Ranjan et al.,2003). Adsorption of As(III) and As(V) onto activated aluminarevealed that the best As(III) and As(V) removal can be carried outat pH 6.1 and 5.2, respectively (Lin and Wu, 2001). Robins et al.(2005) investigated the characteristics of Fe(III) and Al(III) hy-droxides in removing As(III) and As(V) from solution. Fe(OH)3 wasbetter than Al(OH)3 in adsorbing As(V). When Fe(OH)3 was used toremove As(III) and As(V), with 10-fold ratio of Fe(III) to As, the re-sidual concentration of As dropped from 10 mg/L to 0.2 mg/L at pHbetween 6 and 7.5. A comparative study was preformed over theperformance of polyaluminum chloride, aluminum sulfate andferric chloride for the removal of As from groundwater (60.5 mg As/L) (Tubic et al., 2010). Chlorine was utilized as the oxidizing agentleading to the formation of insoluble hydroxides at pH 7. Despitethe fact that excess ferric chloride was required, the freshlyprecipitated hydroxides were able to reduce the As levels to lessthan 10 mg/L. Reddy (2007, 2011) reported development of a noveladsorbent cupric oxide (CuO) whichwas free from limitations of pHor redox potential modification for As removal and its performancewas excellent in the company of competing anions. Additionally,CuO can be regenerated, by leaching with NaOH solution for reuse.The effectiveness of CuO particles was established over a range ofpH from 7.11 to 8.95 wherein competing anions such as sulfate(1.3e735 mg/L), phosphate (0.05e3.06 mg/L) and silica(1e54.5 mg/L) were present (Reddy and Roth, 2013).

On the other hand, several lowecost natural adsorbents arefound to be equally effective as the aforementioned adsorbents.The As(V) removal efficiency by using chitosan showed valuesvaried from 40 to 96.8%, depending upon: (i) tested temperature;(ii) polymer characteristics, and (iii) water composition (Pontoniand Fabbricino, 2012). Another low cost material, laterite soilreduced ~98% of As from initial 0.33 mg/L from groundwaterswithin 30 min (Maji et al., 2008). Amin et al. (2006) also havereported complete removal of both As(III) and As(V) by using ricehusk columns. The conditions were: 100 mg As/L, 6 g rice husk,6.7 and 1.7 ml/min flow rate at pH of 6.5 and 6.0, respectively. Areview presented by Malik et al. (2009) exclusively lists a numberof low cost materials for As removal which could be beneficial for

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developing countries.The presence of natural organic matter in water has also been

reported to delay the adsorption equilibrium and limits the degreeof As(III) and As(V) adsorption (Grafe et al., 2001; Redman et al.,2002). Also, in many cases, the aggressive potential of the toxi-cants reduces after binding to humic substances (Perminova et al.,2006). Redman et al. (2002) studied the effect of natural organicmatter on the adsorption of As onto hematite. Four organic sub-stances were seen to form aqueous complexes with As(V) andAs(III). The extent of complexation varied with the organic matterorigin and increased as the cationic metal (mainly Fe) contentincreased. In addition, organic matter showed active redoxbehavior towards As species. This indicates that the presence oforganic matter may greatly influence redox as well as complexationspeciation of As. Similar reports about humic substances have beenpublished elsewhere (Blinova et al., 2007; Perminova et al., 2007;Zhilin et al., 2004). The presence of amine groups in organic mat-ter play significant role due to their protonation at definite pHvalues (Saada et al., 2003; Sorkina et al., 2014). As(V) sorption ontodifferent forms of kaolinite and two kaolinites coated with humicacids was carried out by Saada et al. (2003). The humic acid coat-ings influenced As sorption, signifying that adsorption firstoccurred on the humic acid sites fully followed by the remaining onkaolinite sites. Studies on zero-valent iron by Mak et al. (2009)suggested that, although the formation of Fe-humate complex inwater delays the As(V) adsorption, As removal effectiveness re-mains practically unaffected in calcium and bicarbonate environ-ment once enough CaCO3 particles are formed.

Sono Arsenic filter and Kanchan™ Arsenic filter are currently inuse in Bangladesh and Nepal (Giles et al., 2011). The Sono filter isregarded as the best of 15 technologies to remove As (Chatterjee,2007; Khan et al., 2000; Hussam and Munir, 2007). It can reduceAs concentration from 1100 mg/L to below the WHO permissiblelimit.

3.2.3. Ion exchange (IE)The application of synthetic ion exchange resins can remove As

species very effectively from drinking water described as by USEPA(An et al., 2011). The extensive reviews summarize the performanceof anion exchange resins, macro reticular resins and cation ex-change resins such as Cu(II), Ce(IV), Fe(III), Y(III), La(III), Zr(IV)(Dambies, 2005; Mohan and Pittman, 2007). The order of exchangecapacity for the most strongebase resins is given below:

HCrO4�

(maximum) > CrO42� > ClO4

� > SeO42� > SO4

2� > NO3� > Br� > (HPO4

2�,HAsO4

2�, SeO32�, CO3

2�) > CN� > NO2� > Cl� > (H2PO4�, H2AsO4�,

HCO3�) > OH� > CH3COO� > F�

For As removal, strongly basic ion exchange resins, particularlyin the chloride form, have been recommended by EPA (Holl, 2010):

R � �NðCH3Þ3

�þ Cl� þH2AsO�4/R � �

NðCH3Þ3�þ H2AsO

�4

þ Cl�

(12)

where, R ¼ matrix phase.Choong et al. (2007) proposed a mechanism of As elimination.

The ion exchange resins are normally loaded with chloride ions in avessel/bed called as exchange sites and the As-laden water is flowndownward through the vessel where ion exchange takes place. Theexhausted resin is regenerated by using aqueous NaCl. However,competing ions such as SO4

2�, NO3�, and F� affect the ion exchange

capacity (Baciocchi et al., 2005; Litter et al., 2010; Sharma and Sohn,2009).

An et al. (2011) showed nearly complete As removal within 1 h,

by employing a new starchebridged magnetite nanoparticles. Arecent work carried out on the As removal from Camarones Riverwater, North Chile demonstrated very good results (Urbano et al.,2012). The river water contained sulfate (154 mg/L), chloride(541 mg/L), boron (15.68 mg/L), chromium (<0.05 mg/L), and totaldissolved solids (1650 mg/L) most of which are known to interferewith As exchange. Water insoluble polymereclay nanocompositeresin (using N-methyl-d-glucamine ligand groups) displayedretention higher than 98% in laboratory studies but decreased to75% in real water samples. Thirunavukkarasu et al. (2002) reportedthe removal capacities of the three As sorption media in thefollowing order: Amberlite IR-120 (max) > iron oxide-coatedsand > manganese greensand.

Resin Tech's strongly basic hybrid anion-exchange resin calledas TECH RESINTECH ASM-10-HP is a specifically prepared sorbentto remove As amid competing ions (Mohan and Pittman, 2007).Several commercial organizations have introduced new tailoredanionic exchangers to achieve As content below 10 mg/L whichinclude resins of Dow Chem, Rohm and Haas, Purolite, Bayer.

As(V) removal is achieved effectively by ion exchange method,with less than 1 mg/L of As in the effluent, while As(III), being un-charged, is not eliminated, and a prior oxidation step is required(Litter et al., 2010; Ravenscroft et al., 2009).

3.2.4. Membrane technology (MT)Membrane technologies, especially RO, have proven reliable for

As removal. RO is probably the best practiced technology which cancompletely purify water andmeet the strict water legislations. Bothlab and pilot-scale experiments have shown more than 95% As(V)and 74% As(III) removal efficiencies achieved by RO (Holl, 2010;Katsoyiannis and Zouboulis, 2006). Membrane processes get ridof As through filtration, electric repulsion, and adsorption of Ascontaining compounds. The mechanism of membrane filtrationwas mentioned earlier in Section 3.1.4.

The distinction between the removal of As(III) and As(V) wasexplored by Seidel et al. (2001) with the help of polysulfone thin-film NF membrane (BQ01). It was observed that elimination ofAs(V) was much higher than that of As(III). Only less than 30% ofAs(III) was removed in contrast to 60e90% of As(V) removal. Flochand Hideg (2004) used pilot scale ZW-1000 (Zenon) membranemodule, with 0.02 mmpore size, for As removal fromwaters and thepilot plant could remove As below 10 mg/L from an initial As con-centrations up to 300 mg/L. Another study on the NF operatingconditions found that the transmembrane pressure, temperatureand crossflow velocity had no effect on As removal (Saitua et al.,2005). These results were supported further by Shih (2005). Thestudies by Harisha et al. (2010) also confirm the aforesaid NFfindings on high As removal (99.80%).

Recently, a different approach was applied by Oehmen et al.(2011) for As elimination from drinking water where a hybrid rigbased on ion exchange membraneecoagulation was used. The finalAs concentration was reduced to 0.3 mg/L from an initial concen-tration of 53.4 mg/L with 99.43% removal efficiency. The hybridmembrane-coagulation system also proved to be better than con-ventional coagulation/filtration process where final As concentra-tionwas reduced to at 3 mg/L from an initial concentration of 57 mg/L. Electrodialysis has similar efficiency as RO which is used pri-marily in treating water with high TDS. Electrodialysis with rever-sion of polarity of the electrodes (EDR) is an improvement of EDwith minimum scaling (Litter et al., 2010; Ravenscroft et al., 2009).

4. Simultaneous removal of As and F

The technologies that allow the simultaneous removal of As andF are essentially similar to the individual removal using adsorption

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(Jing et al., 2012; Li et al., 2011), membrane filtration (Padilla andSaitua, 2010; Nevarez et al., 2011) and coagulation (Pinon-Miramontes et al., 2003; Ingallinella et al., 2011) and adsorptionon various low cost materials (Devi et al., 2008). However, each ofthem presents several benefits and shortcomings. Table 2 presentsthe consolidated information of the recent research work carriedout by various researchers on the above mentioned technologiesfor simultaneous removal of As and F with their merits and de-merits. Fig. 5 compares the simultaneous As and F removalperformance.

4.1. Chemical precipitation/coagulation (CPC)

As discussed earlier, chemical precipitation involves addition ofcake alum and/or ferric chloride in the water body. Pinon-Miramontes et al. (2003) evaluated the combined use of cakealum and a polymeric anionic flocculent (PAF) for the removal of Asand F from drinking water from two wells at Meoqui City, Mexico.As and F concentrations were reduced up to 99 and 77%, respec-tively at US$ 0.38 per m3 of treated water at the optimal pH 7.1. Theauthors found that the efficacy of F removal was dependent on thecake alum quantity used and pH adjustment was needed, whereasAs removal had no effect of pH. Further studies have found thatefficient removal of F and As can be achieved using pre-chlorination, aluminum sulfate and a cationic polyelectrolyte ascoagulant in precipitation (Ingallinella et al., 2011).

ArCISeUNR process was developed and applied to groundwaterin Argentina, where the As and F concentrations vary between 100and 150 mg/L and 1.7e2.5 mg/L, respectively (Ingallinella, 2008).The system consisted of a coagulationeadsorption process, usingpolyaluminum chloride (PAC) as a coagulant with an initial pHadjustment and two filtration stages. Further, the process wasmodified with F and As concentrations ranging from 2.4 to 3.2 mg/Land 60e90 mg/L, respectively (Ingallinella et al., 2011). The As and Fremoval efficiency was up to 85 and 55%, respectively.

It has been shown that electrochemical processes are anattractive alternative to the conventional methods. A primarymechanism of coagulation and electrocoagulationwas explained insections 3.1.1 and 3.2.1. Vasudevan et al. (2011) studied the effect ofvarious coexisting ions on the removal F using electrocoagulation.The solutions with F concentration of 5e20 mg/L were treated withAs(V) (0e5.0mg/L) as a competing ion. Electrocoagulation removedF to the extent of 93, 85.3, 77, 69 and 35% in the presence of As(V)concentrations of 0, 0.5, 1, 3 and 5 mg/L, respectively. The authorsattributed the reduction in F removal to the preferential adsorptionof As(V) ions over F ions with increase in the As(V) concentration.The presence of carbonate, phosphate and silicate also reduced theF removal efficiency.

Zhao et al. (2011) designed an integrated electro-oxidation andelectrocoagulation system to simultaneously remove As(III) and Fions fromwater. By utilizing one Fe plate piece and three parts of Alplate electrodes, which reduced As(III) to less than 10 mg/Lcompared to its initial level of 1 mg/L and F 1 mg/L when its initialconcentration was 4.5 mg/L. Rise in the pH of the solution led toincrease in the As(III) removal efficiency with best removal at 6e7pH. When Fe plate was employed as anode in the electro-coagulation process, As(V) was effectively removed from waterbecause of the co-operation between Fe and As ions (Ratna Kumaret al., 2006). Arsenic and F co-removal by coagulation/precipitationis summarized in Table 2.

4.2. Adsorption (AD)

Adsorption technique is more popular due its simplicity, betterefficiency at high levels of total solids and suitability for household

and small community schemes. Extensive research has been car-ried out using various adsorbents for individual as well as simul-taneous removal of As an F. Adsorbents used for the simultaneousremoval of F and As are activated alumina (Li et al., 2011), activatedcarbon (Jing et al., 2012), layered double hydroxides (Dadwhal et al.,2011; Delorme et al., 2007), ferric hydroxides (Streat et al., 2008),goethite (Tang et al., 2010), FeeCe oxides (Zhang et al., 2010),inorganic ion exchange adsorbents (Chubar, 2011), volcanic ash(Chen et al., 2011), FeeAl doped polymers (Kumar et al., 2011),modified cellulose (Tian et al., 2011), and low cost materials such asgoethite coated sand, hematite coated sand and bone and cow char(Brunson and Sabatini, 2009; Mlilo et al., 2010).

Activated alumina has proved to be one of the best adsorbentsfor the As and F removal. Mechanism of adsorption has been dis-cussed earlier in sections 3.1.2 and 3.2.2. However, the use of thissorbent is limited by its strong dependence on solution pH andcoexisting ions (Liu et al., 2013). To encounter these shortcomings,mesoporous alumina and calcium-doped alumina were synthe-sized (Li et al., 2011). Excellent F and As removal capacities wereobtained by using these materials reducing As(V) concentrationfrom 100 mg/L to 1 mg/L (99% removal). The highest F removal ob-tained was 450 mg/g while 1 g of mesoporous alumina was effec-tive to treat 200 L of As water at pH 7.0. Comparatively, activatedalumina has removal capacity of ~9.0 mg As/g and 7.6 mg F/g (Kuand Chiou, 2002; Lin and Wu, 2001). Jing et al. (2012) developeda composite adsorbent with titania and lanthania supported ongranular activated carbon (TLAC) to effectively remove As(V) and F.Arsenic and F removal was found to be more than 80 and 35%,respectively. On the other hand, Al- and Fe-doped, activated micro(~0.8 mm) and nano (~100 nm) sized porous adsorbents showedsignificant removal of F (~100 mg/g) and As(V) (~40 mg/g) ions(Kumar et al., 2011). Delorme et al. (2007) evaluated mixed oxidessynthesized from the mild thermal treatment of quintinite(Mg4Al2(OH)12CO3$H2O) for the removal of F, As(V) from water.100% As and 80% F removal efficiency was obtained from initialconcentrations of 16 mg/L and 10 mg/L for As and F, respectively.However, CO3 addition led to 90 and 20% of the entrapped F and Asbeing released in the solution confirming that the presence of CO3ions can significantly affect the removal efficiency of mixed oxides.This is in agreement with numerous reports that analyzed thepresence of competing ions such as phosphate, silicate, nitrate,chlorides, carbonates, and sulfates. Detailed information on severalother adsorbent studies are summarized in Table 2. The presence ofhumic acid also affects As and F adsorption on various adsorbents(Dadwhal et al., 2011; Guan et al., 2012; Jimenez-Nunez et al., 2012;Wei et al., 2011). In fact, the coexistence of As and F too affects theindividual removal (Chen et al., 2010, 2011; Zhang et al., 2010).

In order to develop simple and cost effective processes to serveon the community level, several low cost materials have beenevaluated and found to be equally effective in F and/or As removal(Brunson and Sabatini, 2009; Mlilo et al., 2010). Fish bone char andcow bone char were used for treating water with high concentra-tions of As and F (Brunson and Sabatini, 2009). Fish bone char wasbetter in removal of F and As simultaneously with minimalcompetition; F was removed more efficiently than As. Further, theuse of fish bone char is a practical solution for F removal in poorcountries where rural populations cannot meet the expense ofmembranes and electricity. Mlilo et al. (2010) have reported that F,As(III) and As(V) adsorption capacity was higher in bone char thanin goethite coated sand and hematite coated sand.

4.3. Membrane technology (MT)

Membranes have well-proven their use in various processesespecially in desalination, membrane distillation and membrane

Page 11: Arsenic and fl uoride contaminated groundwaters: A review of current technologies for contaminants removal

Table 2Potential treatment methods for the simultaneous removal of As and F.

Technology Investigators and level ofdevelopment

Type of water, raw materials/composition, geographical origin

Maximum removal capacity,optimal/affecting parameters

Reference Merits Demerits Cost

Coagulation � Combination of cake alum andpolymeric anionic flocculent(PAF)

� Pilot plant þ lab scale research

� Groundwater� Composition: Well 1:

F¼ 5.9 mg/L; As¼ 0.139mg/L ;Well 2: F ¼ 4.8 mg/L;As ¼ 0.075 mg/L

� Meoqui City, Chihuahua,Mexico

� F removal ¼ 99%� As removal ¼ 77%� Optimal pH ¼ 7

Pinon-Miramontes et al.(2003)

� Low cost� Simple to� Well prov� Readily av ble

chemicals

� As/F laden sludgegeneration

� Unpleasant watertaste

� Residual aluminum

Lowa

� ArCIS-UNR® processoptimization

� Polyaluminum chloride� Pilot plant

� Groundwater� Composition: F¼ 2.4e3.2mg/LAs ¼ 60e90 mg/L

� F removal ¼ 50e55%� As removal ¼ 75e85%

Ingallinella et al. (2011)

� Direct currentelectrocoagulation processes

� Aluminum alloy as electrodes� Lab scale research

� Synthetic water� Composition:F ¼ 5e20 mg/LAs(V) ¼ 0e5 mg/L

� F removal ¼ 91.5e93%� F removal (For As(V)

concentrations of 0, 0.5, 1, 3and 5 mg/L) ¼ 93, 85.3, 77, 69and 35%, respectively.

Vasudevan et al. (2011)

� integrated electro-oxidationand electrocoagulation (hybridDSA-Fe-Al electrode)

� Synthetic water� Composition: F ¼ 4.5 mg/L

As ¼ 1 mg/L� Current density ¼ mA/cm2

� Duration ¼ 40 min

� F removal ¼ 81%� As(V) removal ¼ 98%� Optimal pH ¼ 5e7

Zhao et al. (2011)

Adsorption � Adsorbent prepared throughthe cross-linking reaction ofPANF by hydrazine hydrateand functionalized reaction ofhydrazine-modified fiber inmixture of sulfur powder andethylenediamine

� Lab scale research

� Synthetic water� Composition: F ¼ 10 mg/L,

PO3¼ 30mg/L As(V)¼ 38mg/L(Separately treated) Mixedions, F ¼ 5 mg/L, PO3 ¼ 50 mg/L, and As(V) ¼ 34.23 mg/Ltreated in another run

� Flow rate ¼ 2.5e3.5 ml/min

� As(V) adsorption¼ 97.9% at pH3.5 to 7

� F adsorption ¼ 90.4% at pH 3� PO3 adsorption > 99% at pH 3

to 5.5� In mixed ions F, As(V) and PO3

adsorption was ~50, 85 and90% respectively

� Equilibrium was reachedwithin 5 min for all theexperiments

Ruixia et al. (2002) � Low to me m cost� Simple to� Efficient� Commerci available

sorbents� Can handl igh levels of

solids

� pH sensitive� Considerable

adsorbentregeneration time

� Needs standby processduring regeneration

� Exhausted adsorbentdisposal problem

� Competing ions reduceefficiency

Low to medium

� CeeFe adsorbent� Lab scale research

� Groundwater� Composition: As(V) ¼ 1.1 mg/L

F ¼ 1.59 mg/L� Zhijiliang Village, Inner

Mongolia, China

� Phosphate seriously affectedremoval of As(V) while F didnot compete with As(V) evenat F/As molar ratio as high as30, suggesting that adsorptionsites for As(V) and F weredifferent

� Mean As(V) adsorptioncapacity ¼ 16 mg/g at pH 3-7

� Max As(V) adsorptioncapacity ¼ 8.3 mg/g at pH 5.5

Zhang et al. (2003)

� Granular activated carbon-based iron-containing adsor-bents (As-GAC)

� Lab scale research

� Synthetic water� Composition: As ¼ 105 mg/L

and 1031 mg/L 90.0 mg solidper 30.0 ml solution

� pH ¼ 4.7� Duration ¼ 24hr

� As removal > 98%� Max As adsorption (prepared

by NaCl oxidation)¼ 6572 mg/g� Presence of P and SiO

significantly decreased As(V)removal at pH > 8.5

� Effects of Cl, and F wereminimal

Gu et al. (2005)

� Synthetic water � F removal ¼ 80% Delorme et al. (2007)

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useenaila

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� Mixed oxides obtained fromthe moderate thermaltreatment of quintinite

� Lab scale research

� Composition:F ¼ 10 mg/L As(V) ¼ 16 mg/LNO3 ¼ 100 mg/L

� As(V) removal ¼ 100%� NO3 removal ¼ 15%� CO3 addition resulted

in trapped ion leaching (90% Fand 20% As released)

� Three types of granular ferrichydroxide materials

� Lab scale research

� Synthetic water� Composition:

As(V) ¼ 0.0133 mmol/LF ¼ 0.0133 mmol/LP ¼ 0.0133 mmol/L

� pH ¼ 4e8

� F adsorptioncapacity ¼ 1.8 mmol/g

� As(V) adsorptioncapacity ¼ 0.9e1 mmol/g

� Phosphate adsorptioncapacity ¼ 0.65e0.75 mmol/g

� Being not a triprotic acid, F didnot compete for same siteswith As

Streat et al. (2008)

� Cow and fish bone char� Lab scale research

� Synthetic water� Composition: F ¼ 10 mg/L

As(V) ¼ 0.250 mg/L

� As(V) showed nosignificant competition for F

� F adsorptioncapacity ¼ 3.94 ± 0.15 mg/g

� As(V) adsorptioncapacity ¼ 4.41 ± 0.23 mg/g

� Bone char showed greatercapacity to remove F than As

Brunson and Sabatini(2009)

� Magnetite-type adsorbent� Lab scale research/Field

sample testing

� Groundwater� Composition:

As ¼ 0.01e3.23 mg/L F ¼ 0.04e3.76 mg/L B ¼ 0.1e33.9 mg/L

� 16 sites, Kyushu, Japan

� Reduction of As concentrationto less than 0.01 mg/L wasobtained up to bedvolume ¼ 200

� Remarks:� The focus was only on As; no

mention on F removal

Yoshizuka et al. (2010)

� Ceramic adsorbent preparedwith a mixture of akadamamud, wheat starch, and Fe2O3

� Lab scale research

� Synthetic water As(V) ¼ 10and 20 mg/L (kinetic studies)As(V) ¼ 5, 10, 20, 50, 65, 80,and 100 mg/L, respectively(isotherm studies)

� As(V) adsorptioncapacity (Langmuirisotherm) ¼ 4.19 mg/g

� Complex multilayer As(V)adsorption was observed onceramic material

� Presence of P and F affectedAs(V) adsorption

Chen et al. (2010)

� Bone char, goethite coatedsand (G-IOCS) and hematitecoated sand (H-IOCS)

� Lab scale research

� Synthetic water� Composition: F ¼ 1e200 mg/L

with or without As (0.25 mg/L) As ¼ 0.1e2.5 mg/L with orwithout F (10 mg/L)

� F and As(III) and As(V)adsorption capacity washigher in bone char than inG-IOCS and H-IOCS

� F removal was not affected bythe presence ofenvironmentally significantAs(III) and As(V)concentrations

� F competes with As(V) foradsorption onto bone char

Mlilo et al. (2010)

� Goethite� Lab scale research

� Synthetic water� Composition:

F ¼ 5.1e25.1 mg/LAs(V) ¼ 2.51e10.12 mg/L

� F adsorptioncapacity ¼ 0.191e0.518 mg/g

� As(V) adsorptioncapacity ¼ 0.247e0.941 mg/g

� F and As adsorption was seenstrongly dependent oncontact time, pH, and surfaceloading

Tang et al. (2010)

(continued on next page)

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Table 2 (continued )

Technology Investigators and level ofdevelopment

Type of water, raw materials/composition, geographical origin

Maximum removal capacity,optimal/affecting parameters

Reference Merits Demerits Cost

� F and As(V) adsorption ontogoethite obeyed pseudosecond-order rate law

� As(V) showed much strongeraffinity for goethite than F

� FeeCe oxide� Lab scale research

� Synthetic water� Composition:

As(V) ¼ 13.3 mmol/L Series ofmolar ratios of As to P (1:0.1,1:1, and 1:10) and As to F (1:1,1:10, and 1:100)

� pH ¼ 5.0 ± 0.2

� P strongly inhibited adsorptionof As(V) at the low-binding-energy sites

� Coexistence of F, onlyinfluenced total adsorptioncapacity of As(V) at highsimultaneous F concentrations

� As(V) and P were mainlyadsorbed through thesubstitution of Fe surfaceactive sites

� F was mainly adsorbedthrough substitution of Cesurface active sites on FeeCesurface

Zhang et al. (2010)

� Adsorption on layered doublehydroxides

� Lab scale research

� Power plant effluent data fromgreater Los Angeles, USA usedto simulate water

� Composition: As ¼ 0.02 mg/LF ¼ 1 mg/L NO3 ¼ 5 mg/LCl ¼ 100 mg/L CO3 ¼ 5 mg/LSO4¼ 100mg/L HPO4 ¼ 1mg/L

� pH ¼ 8

� Effect on As adsorptionF < NO3 < Cl < CO3 < SO4 < P

� Presence of F greatly affectedadsorption equilibriumconstant in As adsorption

� As adsorptioncapacity ¼ 3.6 mg/g

� F adsorptioncapacity ¼ 34.9 mg/g

Dadwhal et al. (2011)

� Inorganic ion exchangersdeveloped based on doublehydrous oxides of Mg and Al

� Lab scale research

� Synthetic water � Very fast kinetics of arsenateadsorption was observed

� As(V) adsorptioncapacity ¼ 220 mg/g

� As(III) adsorptioncapacity ¼ 30e35 mg/g

� Fluoride, bromate, bromide,selenate, borate, etc. competefor adsorption sites

Chubar (2011)

� Adsorption onferric-impregnatedvolcanic ash

� Lab scale research

� Synthetic water and surfacewater

� Composition: As z 1 mg/LF ¼ 0.2e0.5 mg/L

� Lake Kasumigaura, Japan

� As(V) adsorptioncapacity (Langmuirisotherm) ¼ 6.13 mg/g

� Existence of multivalencemetallic cations improvedAs(V) adsorption

� Competing anions (F and P)affected As(V) adsorption

Chen et al. (2011)

� Fe and Al doped micro andnano-polymeric beads

� Lab scale research

� Synthetic water� Composition:

F ¼ 10e100 mg/L As ¼ 1e50 mg/L (Separately treated)

� F adsorptioncapacity ¼ 100 mg/g

� As adsorptioncapacity ¼ 40 mg/g

Kumar et al. (2011)

� Mesoporous alumina andcalcium-doped alumina

� Lab scale research

� Synthetic water� Composition: F ¼ 2e1000 mg/

L As ¼ 100e200 mg/L(Separately treated)

� F adsorptioncapacity ¼ 450 mg/g

� As(V) adsorptioncapacity ¼ 19.8 mg/g

Li et al. (2011)

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� As(III) adsorptioncapacity ¼ 5 mg/g

� N-methylglucamineimmobilized onto cross-linkedchitosan beads

� Lab scale research

� Synthetic water� Composition: As(V) ¼ 0

e150 mg/L F ¼ 0e1 mM

� Adsorption was highly pHdependent

� As(V) adsorptioncapacity ¼ 69.28 mg/g at pH 5

� Effects of competitive anions:SO4 >> P >> F

Wei et al. (2011)

� Cellulose-g-PDMAEMAadsorbent prepared bymodifying surface of nativecellulose fibers with poly (N,N-dimethyl aminoethylmethacrylate)

� Synthetic water� Composition:

F ¼ 1.8e12.8 mg/LAs ¼ 0.05e8.9 mg/L

� F adsorption capacity ¼ 1.5e7.5 mg/g

� As(III) adsorptioncapacity ¼ 0.06e7.8 mg/g

� As(V) adsorptioncapacity ¼ 0.05e8.7 mg/g

� Adsorption capacitiescalculated from Langmuir andFreundlich equations wereboth in the order ofAs(V) >> As(III) > F

Tian et al. (2011)

� Composite adsorbent withtitanium and lanthanumoxides impregnated ongranular activated carbon

� Lab scale research

� Synthetic water andgroundwater

� Groundwater Composition:As(III) ¼ 0.73 mg/LAs(V)¼ 0.69mg/L F¼ 2.01 mg/L TOC ¼ 7.5 mg/L

� pH ¼ 8.0� TLAC ¼ 1 g/L� Shanxi Province, China

� As removal > 80%� F removal > 35%

Jing et al. (2012)

� Nickel and magnesiumhydrotalcite-like compounds(NiAlHT, MgAlHT)

� Lab scale research

� Synthetic water� Composition: F ¼ 5 mg/L 5 ml

of one of the followingsolutions: Cl ¼ 20 mg/L,SO4 ¼ 35 mg/L orAs(V) ¼ 2 mg/L to 50 mg ofeach hydrotalcite-likecompound

� Speed ¼ 200 rpm

� The interference of otheranions in the sorption kineticof F ions by NiAlHT andMgAlHT was: SO4 > As(V) > Cl

Jimenez-Nunez et al. (2012)

Membranefiltration

� Combination of solar energyand NF/RO (PV-membrane)

� Pilot plant

� Groundwater� Composition:

F z 10 mg/L As z 5e6 mg/LMg z 150 mg/L � Pine HillStation and Ti Tree Farm,Australia

� F rejection � 88%� As rejection ¼ 78%� Mg rejection ¼ 99%

Richards et al. (2009) � Highly efficient� No chemicals required� Does not influence water

taste and color� Ability to completely

purify water

� High initial cost� High operating cost� High water rejection� Brine disposal

problem� Need of after

treatment re-mineralization

High

� Nanofiltration� Pilot plant

� Synthetic water� Composition As(V) ¼ 180 mg/L

F ¼ 5 mg/L HCO3 ¼ 84 mg/L� pH ¼ 8� Pressure ¼ 7 bar

� As(V) rejection ¼ 93%� F rejection ¼ 89%� HCO3 rejection ¼ 85%

Padilla and Saitua (2010)

� Solar (photovoltaic) poweredUFeNF/RO system

� Lab scale research

� Groundwater� Composition: F ¼ 1.1 and

0.464 mg/L As ¼ 0.005 and0.003 mg/L TDS ¼ 5700 and1080 mg/L

� Pine Hill and Ti Tree, Australia

� More than 85% overallrejection

� As rejection ¼ ~64e79% onBW30, TFC-S, ESPA4, andNF90 membranes

� F rejection ¼ ~98.5% on BW30membrane

� Rejection of arsenic wasindependent of pH from3 to 11

Richards et al. (2011)

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Page 15: Arsenic and fl uoride contaminated groundwaters: A review of current technologies for contaminants removal

Table

2(con

tinu

ed)

Tech

nolog

yInve

stigatorsan

dleve

lof

dev

elop

men

tTy

peof

water,raw

materials/

composition,g

eograp

hical

origin

Max

imum

remov

alcapacity,

optimal/affectingparam

eters

Referen

ceMerits

Dem

erits

Cost

�En

ergy

variations

(solar

irradiance

betw

een0.2

and1.0kW

/m2)influen

cedF

rejection

�Nan

ocom

posite(N

F/RO)

mem

bran

esprepared

byva

por-inducedphasesepara-

tion

method

from

propionated

lignin

andcellu

lose

triacetate

�Labscaleresearch

�Groundwater

�Com

position:

11.8

mg/LAs¼

0.43

5mg/L

�pH

¼7.17

�Chihuah

ua,

Mex

ico

�Asrejection¼

17.80e

25.40%

�Frejection¼

14.29e

27.14%

�Asan

dFremov

alby

mem

bran

eswas

foundto

beaffected

byionic

andorga

nic

matterpresentingrou

ndwater

Nev

arez

etal.(20

11)

Others

�Filtration

�Filtration

onhom

e-mad

efilter

med

ia�

Pilotplant

�Drinkingwater

�Com

position:

5mg/LAs¼

0.13

mg/L

�Unkn

ownsource,

Prob

ably

India

�Fremov

al¼

85.60%

(0.72mg/L)

�Asremov

al¼

93.07%

(0.009

mg/L)

Dev

ietal.(20

08)

Low

�Mem

bran

efiltration

/Distilla

tion

�Directco

ntact

mem

bran

edistilla

tion

(DCMD)using

polyp

ropylen

ean

dpolytetrafluoroe

thylen

emem

bran

es�

Labscalepilo

tplant

�Sy

nthetic

water

and

brackish

water

�Brack

ish

water

composition:

Dissolved

solid

1000

e10

,000

mg/LAsan

dU

¼10

e40

0mg/LF¼

1e30

mg/L

�Dissolved

solid

sco

ncentrationsless

than

20ppm

(>99

%rejectionof

salts)

�As,

Fan

dU

reduction¼

~96.5

e99

.9%

Yarlaga

ddaet

al.(20

11)

Veryhigh

Thebo

ldtext

represents

theco

untryof

grou

ndwater

source.

aTh

ecitedliterature

doe

snot

give

actual

costsan

dhen

cethis

isrelative

.

S.V. Jadhav et al. / Journal of Environmental Management 162 (2015) 306e325320

reactors. As described earlier, although there are several reportson F as well as As removal from synthetic aqueous solutions byemploying RO and NF processes with high removal efficiencies,only a few reports have dealt with natural groundwater (Nevarezet al., 2011). A widely known separation mechanism has alreadybeen described in section 3.1.4.

A series of experiments were performed in Central Australia toevaluate elemental retention with four different membranemodules (BW30, ESPA4, NF90, and TFC-S) at different pH valuesranging from 3 to 11 (Richards et al., 2009). A pilot plant usingsolar energy and a two-staged membrane process consisting of UFfollowed by NF/RO was developed for water purification. Theaverage removal of F and As was found to be nearly 88 and 78%,respectively, on NF90 membrane. Moreover, F and As removal wasobserved to be independent of pH. Average retention of As was 79,65, and 75% for the BW30, TFC-S, and ESPA4 membranes,respectively. It has been suggested that variations in retentionbased on membrane type were likely due to membrane charac-teristics. Further, the samemembraneswere used in another studyfor photovoltaic powered UFeNF/RO system in real water treat-ment to confirm the results (Richards et al., 2011). A recent studyon forward osmosis (FO) has demonstrated promising results(~95%) for As(V) removal in presence of F (Mondal et al., 2014). Apre-oxidation of As(III) was necessary for efficient As removal atpH 7. Also, a “two pass” FO-RO system was proven to be moresustainable than a “two pass” RO system.

A pilot scale NF plant was operated to evaluate performance onsimultaneous removal of As, F and HCO3 from a synthetic watersolution laden with 180 mg As(V)/L, 5 mg F/L and 84 mg HCO3/L(Padilla and Saitua, 2010). At 7e8 bar, the removal of As and F was93 and 89%, respectively. However, reducing the pressure to 2 barreduced the removal efficiency to 91.6 and 73.3% for As and F,respectively. These findings are in consonance with the so-called“dilution effect”; at higher pressures, the permeate water fluxincreases more than the salt flux (Seidel et al., 2001). Therefore,the salt concentration in permeate is reduced due to increasedremoval. Further, by reducing the pressure, the convection is lowand consequently, the diffusive contribution becomes significant.Similar findings have been reported by other workers as listed inTable 2.

An interesting investigation carried out on nanocompositemembranes suggested that As and F removal can be influenced byionic and organic matter content in groundwater (Nevarez et al.,2011). Nanocomposite membranes synthesized from propio-nated lignin (such as Kraft, Organosolv and Hydrolytic) and cel-lulose triacetate (CTA), removed 17.80e25.40% As and14.29e27.14% F. Membrane effectiveness was also influenced bysuspended solids (Meenakshi et al., 2004).

There are several RO plants operating in Argentina and Mexicofor F and As removal. Regardless of their high separation efficiency,RO systems suffer from considerable water loss (35e65%) due tothe discharge of concentrated retentate stream which should betreated before being discharged. However, there are no means totreat or safely dispose the rejected brine. Moreover, poor com-munities cannot afford the high running cost (Ingallinella et al.,2011).

4.4. Other technologies

In a quest to develop appropriate technology for the concurrentelimination of As and F, a limited number of researchers havemade out of the box efforts to see the opportunities. Devi et al.(2008) carried out removal of F and As by modified home-madefilter media for potable water. The system consisted of twometal tanks, each with 30 cm diameter and 100 cm height, fitted

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S.V. Jadhav et al. / Journal of Environmental Management 162 (2015) 306e325 321

with 1.25 cm outlet pipe, a drain valve and an outlet tap. One tankwas filled with 10 cm stone at bottom (pebbles); 8 cm filter gravelconsisting of two layers of different sizes of 4 cm deep each (particlesize ranges 0.8e1.5 mm) and a layer at the top of 40 cm deep filtersand (size of 0.2e0.8 mm). The second tank was also filled similarlyexcept that a 10 cm crushed brick (particle size ranging from 0.25 to0.5 mm) was added to operate the experiments in batches for 2, 4,6, 8, 10 and 12 h. The initial concentrations of F and As were kept at5 mg/L and 0.13 mg/L, respectively during the experiment. Thissimple set-up was effective to remove F and As nearly by 86 and93%, respectively.

Yarlagadda et al. (2011) used a different approach of directcontact membrane distillation process for the recovery of potablewater from As, U and F contaminated groundwaters. Polypropyleneand polytetrafluoroethylene membranes were evaluated withsynthetic brackish water composition: As and U: 10e400 mg/L; F:1e30mg/L; and salts: 1000e10,000mg/L. The results showedmorethan 99% removal of salts along with As, F and U removal in therange of 96.5e99.9%.

5. Disposal of trapped/separated As and F

Although a lot of work has taken place to remove As and F inisolation or together from a mosaic of ions, the real worry is two-fold: how to dispose of the concentrate or retentate and how tostop its recycle back into the groundwaters. Communities using anyof the low-cost technologies to make their local potable watersupply free of As and F, also need to be provided with low-cost andeffective means of dealing with the loaded and exhausted adsor-bents or concentrated brines. There is no worthwhile technologyavailable except the disposal of concentrated streams in sea.

The foregoing discussion illustrated that successful treatment ofwater containing high dissolved solids (TDS) can be carried out byusing activated alumina (AA). Conversely, the presence ofcompeting ions (sulfates, nitrates, selenium, chlorides, etc.) mayseriously affect the adsorption rates. Nearly 5e10% loss of absorp-tive sites for every run should be considered as a benchmark whileseparating As(V) with activated alumina. This is due to high

Fig. 5. Simultaneous fluoride and arsenic removal performance of various technologies. Wh33 ¼ Zhao et al. (2011); AD-34 ¼ Ruixia et al. (2002); AD-35 ¼ Jing et al. (2012); AD-36 ¼ Bru(2011); RO/NF-39 ¼ Padilla and Saitua (2010); RO/NF-310 ¼ Nevarez et al. (2011); Other-3Delorme et al. (2007) should be taken as this is not shown in figure due to drawing constrainAs/L and 10 mg F/L.

selectivity of activated alumina towards As(V) resulting in regen-eration problems.

Pre-oxidation step is required to convert As(III) to As(V) forpractical removal of As(III). Strong dependency on pH limits theapplicability of adsorption. Moreover, regeneration steps result insecondary pollution which is also applicable to ion exchange;although in the case of ion exchange resins, high cost of resins isalways associated with high removal (~95%) performance for Asand F (Mohan and Pittman, 2007; Solangi et al., 2009). Fluoride,sulfate, nitrate, selenium and phosphate are competitive specieswith arsenic affecting the duration of adsorption. Improvedremoval along with the reduction in regeneration cycle can beachieved by passing of water through a series of columns. Ion ex-change beds are susceptible to clogging due to the presence ofsuspended solids and pretreatment is recommended whichotherwise escalates the equipment and operating cost (Shah,2008).

More than 95% As and F removal is achieved by RO along withcomplete purification and disinfectionwhen the operating pressureis ideal (Dolar et al., 2011; Oehmen et al., 2011). For instance, Fig. 5demonstrates that RO and NF are themost useful technologies in Asand F removal. Literature reports illustrate that electrodialysisreversal can eliminate 80% of the pollutants (Litter et al., 2010;Ravenscroft et al., 2009). However, the release of brine is also ofgreat concern. Moreover, these membranes suffer from 35 to 65%water loss at retentate side which should be treated before beingdischarged. Although membrane distillation has shown promisingco-removal potential, it turns out to be the most expensive tech-nique for As and F removal (Fig. 5). Fig. 5 also shows that co-presence of As and F results in nearly 15e20% reduction inremoval efficiency of any treatment method. Therefore, consider-ation must also be given to this issue while synthesizing and/orselecting the treatment route. On the other hand, although costeffective, the precipitation scheme for F removal leaves toxic re-sidual aluminum complex in drinking water.

The synthesis of nanosized adsorbents and encapsulationtechnologies to isolate loaded adsorbents and dispose them aslandfill or for burial will be highly useful. Synthesis of highly

ere, CPC-31 ¼ Pinon-Miramontes et al. (2003); CPC-32 ¼ Ingallinella et al. (2011); EC-nson and Sabatini (2009); RO/NF-37 ¼ Richards et al. (2009); RO/NF-38 ¼ Richards et al.11 ¼ Devi et al. (2008); Other-312 ¼ Yarlagadda et al. (2011). Note: A special note ofts. The authors obtained 100% As and 80% F removal from initial concentrations 16 mg

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selective nanomaterials for membranes could be used for both Asand F removal. Activated alumina treatment is pH dependent andhence treatment of water with mineral acids will be required. This,however, needs further research, particularly sustainable means ofcontaminants laden sorbents. Rice husk, bone char, red mud, coal,sand, and some other low cost materials available in large quanti-ties, possibly can be used as adsorbents. Developing a technologybased on these materials could prove to be a practical solution indeveloping markets. For example, some researchers have gotexcellent As (93%) and F (86%) co-removal on relatively inexpensivehome-made filter media by combining sand and crushed bricks(Devi et al., 2008).

6. Conclusions

The literature analysis on As and F removal leads to thefollowing conclusions:

1. The technologies available for the simultaneous removal of Asand F are divided broadly into three, namely, coagulation,adsorption and membrane processes. The process with veryhigh efficiency for the removal of individual contaminants is notnecessarily suitable for the simultaneous removal of both As andF.

2. At present, the most capable treatment method for As and Fremoval is the RO and NF with the marginal reduction in per-formance in the company of competing ions. However, highfixed cost associated with the membrane plants is a majorsetback for rural populations. Apart from the operating costs,the rural masses face another set of problems in terms of limited(or irregular) electricity supply for water pumping, washing offouled membrane and scraping.

3. The sorption materials seldom make it to the practical utilitydespite of their proven high efficiency of As and F removal. Theproblem with the adsorbents is the competing ions and theiraffinity for the same adsorption sites. The presence of organicmatter has a profound effect on adsorption in terms of delayingthe adsorption equilibrium.

4. Extensive research is required for the development and imple-mentation of a low-cost, sustainable and hybrid technologywhich can overcome the drawbacks of the individual process forthe simultaneous removal of As and F.

5. There is no meaningful knowledge available for the disposal ofremoved As and/or F from groundwaters. Innovative encapsu-lation methods to isolate As and F loaded materials for finalpermanent disposal or burial without any risk of furthercontamination may provide an effective solution, but they areyet to be developed.

Conflicts of interest

The authors declare no conflict of interest.

Acknowledgments

This work is part of the project sponsored by the EUe India NewIndigo Project of Spain (I. Ortiz), India (G.D. Yadav) and Finland (R.Keiski). Financial support from the Spanish Ministry of Economyand Competitiveness through the projects CTQ2008-00690,CTQ2012-31639 and INDIGO-DST1-017 Govt. of India is gratefullyacknowledged.

Appendix A. Supplementary data

Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.jenvman.2015.07.020.

References

Abuzaid, N.S., Bukhari, A.A., Hamouz, Z.M., 2002. Ground water coagulation usingsoluble stainless steel electrodes. Adv. Environ. Res. 6 (3), 325e333.

Ahmed, M.F., 2001. An overview of arsenic removal technologies in Bangladesh andIndia. Technologies for arsenic removal from drinking water. In: InternationalWorkshop on Technologies for Arsenic Removal from Drinking Water Orga-nized by Bangladesh University of Engineering and Technology (BUET), Dhaka.Bangladesh and The United Nations University (UNU), Tokyo, Japan,pp. 251e269.

Ahn, J.S., 2012. Geochemical occurrences of arsenic and fluoride in bedrockgroundwater: a case study in Geumsan County, Korea. Environ. Geochem.Health 34, 43e54.

Akter, A., Ali, M.H., 2011. Arsenic contamination in groundwater and its proposedremedial measures. Int. J. Environ. Sci. Tech. 8 (2), 433e443.

Alarcon-Herrera, M.T., Bundschuh, J., Nath, B., Nicolli, H.B., Gutierrez, M., Reyes-Gomez, V.M., Nunez, D., Martin-Dominguez, I.R., Sracek, O., 2013. Co-occurrenceof arsenic and fluoride in groundwater of semi-arid regions in Latin America:genesis, mobility and remediation. J. Hazard. Mater. 262, 960e969.

Amin, Md. N., Kaneco, S., Kitagawa, T., Begum, A., Katsumata, H., Suzuki, T., Ohta, K.,2006. Removal of arsenic in aqueous solutions by adsorption onto waste ricehusk. Ind. Eng. Chem. Res. 45, 8105e8110.

An, B., Liang, Q., Zhao, D., 2011. Removal of arsenic(V) from spent ion exchange brineusing a new class of starch-bridged magnetite nanoparticles. Water Res. 45e5,1961e1972.

Anirudhan, T.S., Unnithan, M.R., 2007. Arsenic(V) removal from aqueous solutionsusing an anion exchanger derived from coconut coir pith and its recovery.Chemosphere 66 (1), 60e66.

Aoudj, S., Drouiche, N., Hecinim, M., Ouslimanem, T., Palaouane, B., 2012. Coagu-lation as a post-treatment method for the defluoridation of photovoltaic cellmanufacturing wastewater. Procedia Eng. 33, 111e120.

Ayoob, S., Gupta, A.K., Bhat, V.T., 2008. A conceptual overview on sustainabletechnologies for the defluoridation of drinking water. Crit. Rev. Environ. Sci.Technol. 38, 401e470.

Baciocchi, R., Chiavola, A., Gavasci, R., 2005. Ion exchange equilibria of arsenic in thepresence of high sulfate and nitrate concentrations. Water Sci. Technol. WaterSupply 5 (5), 67e74.

Balasubramanian, N., Kojima, T., Basha, A.C., Srinivasakannan, C., 2009. Removal ofarsenic from aqueous solution using electrocoagulation. J. Hazard. Mater. 167,966e969.

Bansiwal, A., Pillewan, P., Biniwale, R.B., Rayalu, S.S., 2010. Copper oxide incorpo-rated mesoporous alumina for defluoridation of drinking water. MicroporousMesoporous Mater. 129, 54e61.

Baskan, M.B., Pala, A., 2010. A statistical experiment design approach for arsenicremoval by coagulation process using aluminum sulfate. Desalination 254,42e48.

Behbahani, M., Alavi Moghaddam, M.R., Arami, M., 2011. Techno-economical eval-uation of fluoride removal by electrocoagulation process: optimization throughresponse surface methodology. Desalination 271, 209e218.

Bennajah, M., Gourich, B., Essadki, A.H., Vial, Ch, Delmas, H., 2009. Defluoridation ofMorocco drinking water by electrocoagulation/electroflottation in an electro-chemical external-loop airlift reactor. Chem. Eng. J. 148, 122e131.

Bhatnagar, A., Kumar, E., Sillanpaa, M., 2011. Fluoride removal from water byadsorptionda review. Chem. Eng. J. 171, 811e840.

Bhattacharya, P., Claesson, M., Bundschuh, J., Sracek, O., Fagerberg, J., Jacks, G.,Martin, R.A., Storniolo, A.R., Thir, J.M., 2006. Distribution and mobility of arsenicin the Río Dulce alluvial aquifers in Santiago del Estero Province, Argentina. Sci.Total Environ. 358, 97e120.

Biswas, K., Gupta, K., Ghosh, U.C., 2009. Adsorption of fluoride by hydrous iron(III)etin(IV) bimetal mixed oxide from the aqueous solutions. Chem. Eng. J. 149,196e206.

Blinova, O., Novikov, A., Perminova, I., Goryachenkova, T., Haire, R., 2007. Redoxinteractions of Pu(V) in solutions containing different humic substances.J. Alloy. Compd. 444e445, 486e490.

Brunson, L.R., Sabatini, D.A., 2009. An evaluation of fish bone char as an appropriatearsenic and fluoride removal technology for emerging regions. Environ. Eng. Sci.26 (12), 1777e1784.

Camacho, L.M., Gutierrez, M., Alarcon-Herrera, M.T., Villalba, M.L., Deng, S., 2011.Occurrence and treatment of arsenic in groundwater and soil in northernMexico and southwestern USA. Chemosphere 83 (3), 211e225.

CDC, 1993. Center for Dieases Control and Prevention, Fluoridation Census 1992.Cengeloglu, Y., Kir, E., Ersoz, M., 2002. Removal of fluoride from aqueous solution by

using red mud. Sep. Purif. Technol. 28, 81e86.Chakraborti, D., Das, B., Murrill, M.T., 2011. Examining India's groundwater quality

management. Environ. Sci. Technol. 45, 27e33.Chakraborti, D., Rahman, M.M., Das, B., Murrill, M., Dey, S., Mukherjee, S.C., 2010.

Status of groundwater arsenic contamination in Bangladesh: a 14-year studyreport. Water Res. 44 (19), 5789e5802.

Page 18: Arsenic and fl uoride contaminated groundwaters: A review of current technologies for contaminants removal

S.V. Jadhav et al. / Journal of Environmental Management 162 (2015) 306e325 323

Chatterjee, R., 2007. Chemist wins Grainger challenge for sustainability. Environ.Environ. Sci. Technol. 41, 2660.

Chauhan, V.S., Dwivedi, P.K., Iyengar, L., 2007. Investigations on activated aluminabased domestic defluoridation units. J. Hazard. Mater. 139 (1), 103e107.

Chen, R., Zhang, Z., Feng, C., Huc, K., Li, M., Li, Y., Shimizu, K., Chen, N., Sugiura, N.,2010. Application of simplex-centroid mixture design in developing and opti-mizing ceramic adsorbent for As(V) removal from water solution. MicroporousMesoporous Mater. 131, 115e121.

Chen, R., Zhang, Z., Feng, C., Huc, K., Li, M., Li, Y., Shimizu, K., Chen, N., Sugiura, N.,2011. Use of ferric-impregnated volcanic ash for arsenate (V) adsorption fromcontaminated water with various mineralization degrees. J. Colloid Interf. Sci.353, 542e548.

Choong, T.S.Y., Chuah, T.G., Robiah, Y., Koay, F.L.G., Azni, I., 2007. Arsenic toxicity,health hazards and removal techniques from water: an overview. Desalination217, 139e166.

Chouhan, S., Flora, S.J.S., 2010. Arsenic and fluoride: two major groundwater pol-lutants. Indian J. Exp. Biol. 48, 666e678.

Chuang, C.L., Fan, M., Xu, M., Brown, R.C., Sung, S., Saha, B., Huang, C.P., 2005.Adsorption of arsenic (V) by activated carbon prepared from oat hulls. Che-mosphere 61 (4), 478e483.

Chubar, 2011. New inorganic (an)ion exchangers based on MgeAl hydrous oxides:(alkoxide-free) solegel synthesis and characterization. J. Colloid Interf. Sci. 357,198e209.

Chubar, N.I., Samanidou, V.F., Kouts, V.S., Gallios, G.G., Kanibolotsky, V.A.,Strelko, V.V., Zhuravlev, I.Z., 2005. Adsorption of fluoride, chloride, bromide, andbromate ions on a novel ion exchanger. J. Colloid Interf. Sci. 291, 67e74.

Currell, M., Cartwright, I., Raveggi, M., Han, D., 2011. Controls on elevated fluorideand arsenic concentrations in groundwater from the Yuncheng Basin, China.Appl. Geochem. 26, 540e552.

Dadwhal, M., Sahimi, M., Tsotsis, T.T., 2011. Adsorption isotherms of arsenic onconditioned layered double hydroxides in the presence of various competingions. Ind. Eng. Chem. Res. 50, 2220e2226.

Dambies, L., 2005. Existing and prospective sorption technologies for the removal ofarsenic in water. Sep. Sci. Technol. 39 (3), 603e627.

Delorme, F., Seron, A., Gautier, A., Crouzet, C., 2007. Comparison of the fluoride,arsenate and nitrate anions water depollution potential of a calcined quintinite,a layered double hydroxide compound. J. Mater. Sci. 42, 5799e5804.

Devi, R., Alemayehu, E., Singh, V., Kumar, A., Mengistie, E., 2008. Removal of fluo-ride, arsenic and coliform bacteria by modified homemade filter media fromdrinking water. Bioresour. Technol. 99, 2269e2274.

Diaz-Barriga, F., Navarro-Quezada, A., Grijalva, M.I., Grimaldo, M., Loyola-Rodriguez, J.P., Ortiz, M.D., 1997. Endemic fluorosis in Mexico. Fluoride 30 (4),233e239.

Dolar, D., Kosutic, K., Vucic, B., 2011. RO/NF treatment of wastewater from fertilizerfactory e removal of fluoride and phosphate. Desalination 265 (1e3), 237e241.

Elazhar, F., Tahaikt, M., Achatei, A., Elmidaoui, F., Taky, M., El Hannouni, F., Laaziz, I.,Jariri, S., El Amrani, M., Elmidaoui, A., 2009. Economical evaluation of thefluoride removal by nanofiltration. Desalination 249, 154e157.

Emamjomeh, M.M., Sivakumar, M., 2009. Review of pollutants removed by elec-trocoagulation and electrocoagulation/flotation processes. J. Environ. Manag.90, 1663e1679.

Ergun, E., Tor, A., Cengeloglu, Y., Kocak, I., 2008. Electrodialytic removal of fluoridefromwater: effects of process parameters and accompanying anions. Sep. Purif.Technol. 64, 147e153.

Essadki, H., Gourich, B., Ch, Vial, Delmas, H., Bennajah, M., 2009. Defluoridation ofdrinking water by electrocoagulation/electroflotation in a stirred tank reactorwith a comparative performance to an external-loop airlift reactor. J. Hazard.Mater. 168, 1325e1333.

Fan, X., Parker, D.J., Smith, M.D., 2003. Adsorption kinetics of fluoride on low costmaterials. Water Res. 37, 4929e4937.

Farooqi, A., Masuda, H., Firdous, N., 2007. Toxic fluoride and arsenic contaminatedgroundwater in the Lahore and Kasur districts, Punjab, Pakistan and possiblecontaminant sources. Environ. Pollut. 145, 839e849.

Fernandez-Turiel, J.L., Garcia-Valles, M., Gimeno-Torrente, D., Saavedra-Alonso, J.,Martinez-Manent, S., 2005. The hot spring and geyser sinters of El Tatio,Northern Chile. Sediment. Geol. 180 (3e4), 125e147.

Fewtrell, L., Smith, S., Kay, D., Bartram, J., 2006. An attempt to estimate the globalburden of disease due to fluoride in drinking water. J. Water Health 533e542.

Floch, J., Hideg, M., 2004. Application of ZW-1000 membranes for arsenic removalfrom water sources. Desalination 162, 75e83.

Flora, S.J.S., Mittal, M., Mishra, D., 2009. Co-exposure of arsenic and on oxidativestress, glutathione linked enzymes, biogenic amines and DNA damage in mousebrain. J. Nurol. Sci. 285, 198.

Ganvir, V., Das, K., 2011. Removal of fluoride from drinking water using aluminumhydroxide coated rice husk ash. J. Hazard. Mater. 185 (2e3), 1287e1294.

Ghorai, S., Pant, K.K., 2005. Equilibrium, kinetics and breakthrough studies foradsorption of fluoride on activated alumina. Sep. Purif. Sci. 42 (3), 265e271.

Gilbert, B., Ono, R.K., Ching, K.A., Kim, C.S., 2009. The effects of nanoparticle ag-gregation processes on aggregate structure and metal uptake. J. Colloid Interf.Sci. 339,285e339,295.

Giles, D.E., Mohapatra, M., Issa, T.B., Anand, S., Singh, P., 2011. Iron and aluminiumbased adsorption strategies for removing arsenic fromwater. J. Environ. Manag.92, 3011e3022.

Gong, W.X., Qu, J.H., Liu, R.P., Lan, H.C., 2012a. Effect of aluminum fluoridecomplexation on fluoride removal by coagulation. Colloid. Surf. A 395, 88e93.

Gong, W.X., Qu, J.H., Liu, R.P., Lan, H.C., 2012b. Adsorption of fluoride onto differenttypes of aluminas. Chem. Eng. J. 189e190, 126e133.

Grafe, M., Eick, M.J., Grossi, P.R., 2001. Adsorption of arsenate(V) and arsenite(III) ongoethite in the presence and absence of dissolved organic carbon. Soil Sci. Soc.Am. J. Div. S2 Soil Chem. 65, 1680e1687.

Gregor, J., 2001. Arsenic removal during conventional aluminium-based drinking-water treatment. Water Res. 35 (7), 1659e1664.

Gu, Z., Fang, J., Deng, B., 2005. Preparation and evaluation of GAC-based iron-con-taining adsorbents for arsenic removal. Environ. Sci. Technol. 39 (10),3833e3843.

Guan, X., Du, J., Meng, X., Sun, Y., Sun, B., Hu, Q., 2012. Application of titanium di-oxide in arsenic removal fromwater: a review. J. Hazard. Mater. 215e216, 1e16.

Han, M., Kwon, A., 2002. Preliminary investigation of electrocoagulation as a sub-stitute for chemical coagulation. Water Sci. Technol. Water Supply 2 (5e6),73e76.

Harisha, R.S., Hosamani, K.M., Keri, R.S., Natarajm, S.K., Aminabhavi, T.M., 2010.Arsenic removal from drinking water using thin film composite nanofiltrationmembrane. Desalination 252 (1e3), 75e80.

Holl, W.H., 2010. Mechanisms of arsenic removal from water. Environ. Geochem.Health 32, 287e290.

Holt, P.K., Barton, G.W., Wark, M., Mitchell, C.A., 2002. A quantitative comparisonbetween chemical dosing and electrocoagulation. Colloid. Surf. A 211 (2e3),233e248.

Hu, C.Y., Lo, S.L., Kuan, W.H., 2003. Effects of co-existing anions on fluoride removalin electrocoagulation (EC) process using aluminum electrodes. Water Res. 37,4513e4523.

Hu, C.Y., Lo, S.L., Kuan, W.H., 2005. Effects of the molar ratio of hydroxide andfluoride to Al(III) on fluoride removal by coagulation and electrocoagulation.J. Colloid Interf. Sci. 283, 472e476.

Hu, K., Dickson, J.M., 2006. Nanofiltration membrane performance on fluorideremoval from water. J. Membr. Sci. 279, 529e538.

Hug, S.J., Leupin, O.X., Berg, M., 2008. Bangladesh and Vietnam: different ground-water compositions require different approaches to arsenic mitigation. Environ.Sci. Technol. 42 (17), 6318e6323.

Hussam, A., Munir, A.K.M., 2007. A simple and effective arsenic filter based oncomposite iron matrix: development and deployment studies for groundwaterof Bangladesh. J. Environ. Sci. Health A 42, 1869e1878.

Ingallinella, A.M., 2008. Invention Patent, Procedure for the removal of arsenic andfluoride in groundwater 1999-2009. Regist. No AR051530b1, (in Spanish).

Ingallinella, A.M., Pacini, V.A., Fern�andez, R.G., Vidoni, R.M., Sanguinetti, G., 2011.Simultaneous removal of arsenic and fluoride from groundwater bycoagulation-adsorption with polyaluminum chloride. J. Environ. Sci. Health A46, 1288e1296.

Islam, M., Patel, R.K., 2007. Evaluation of removal efficiency of fluoride fromaqueous solution using quick lime. J. Hazard. Mater. 143, 303e310.

Jadhav, S.V., Gadipelly, C.R., Marathe, K.V., Rathod, V.K., 2014. Treatment of fluorideconcentrates from membrane unit using salt solutions. J. Water Proc. Eng. 2,31e36.

Jakariya, M., Bhattacharya, P., 2007. Use of GIS in local level participatory planningfor arsenic mitigation: a case study fromMatlab Upazila, Bangladesh. J. Environ.Sci. Health 42 (12), 1933e1944.

Jakariya, M., Chowdhury, A.M.R., Hossain, Z., Rahman, M., Sarker, Q., Khan, R.I.,2003. Sustainable community-based safe water options to mitigate theBangladesh arsenic catastrophe e an experience from two Upazilas. Curr. Sci. 85(2), 141e146.

Jakariya, M., Vahter, M., Rahman, M., Wahed, M.A., Hore, S.K., Bhattacharya, P., 2007.Screening of arsenic in tubewell water with field test kits: evaluation of themethod from public health perspective. Sci. Total Environ. 379 (2e3), 167e175.

Jimenez-Nunez, M.L., Solache-Rios, M., Chavez-Garduno, J., Olguin-Gutierrez, M.T.,2012. Effect of grain size and interfering anion species on the removal offluoride by hydrotalcite-like compounds. Chem. Eng. J. 181e182, 371e375.

Jing, C., Cui, J., Huang, Y., Li, A., 2012. Fabrication, characterization, and application ofa composite adsorbent for simultaneous removal of arsenic and fluoride. Mater.Interf. 4, 714e720.

Katsoyiannis, I.A., Zouboulis, A.I., 2006. Comparative evaluation of conventional andalternative methods for the removal of arsenic from contaminated groundwa-ters. Rev. Environ. Health 21 (1), 25e41.

Kettunen, R., Keskitalo, P., 2000. Combination of membrane technology and lime-stone filtration to control drinking water quality. Desalination 131, 271e283.

Khan, A.H., Rasul, S.B., Munir, A.K.M., Habibuddowla, M., Alauddin, M., Newaz, S.S.,Hussam, A., 2000. Appraisal of a simple arsenic removal method for groundwater of Bangladesh. Sci. Health A 35, 1021e1041.

Khatibikamal, V., Torabian, A., Janpoor, F., Hoshyaripour, G., 2010. Fluoride removalfrom industrial wastewater using electrocoagulation and its adsorption ki-netics. J. Hazard. Mater. 179, 276e280.

Kim, S.H., Kim, K., Ko, K.S., Kim, Y., Lee, K.S., 2012. Co-contamination of arsenic andfluoride in the groundwater of unconsolidated aquifers under reducing envi-ronments. Chemosphere 87, 851e856.

Kobya, M., Gebologlu, U., Ulu, F., Oncel, S., Demirbas, E., 2011. Removal of arsenicfrom drinking water by the electrocoagulation using Fe and Al electrodes.Electrochim. Acta 56, 5060e5070.

Ku, Y., Chiou, H., 2002. The adsorption of fluoride ion from aqueous solution byactivated alumina. Water Air Soil Pollut. 133, 349e361.

Kumar, N.S., Goel, S., 2010. Factors influencing arsenic and nitrate removal fromdrinking water in a continuous flow electrocoagulation (EC) process. J. Hazard.

Page 19: Arsenic and fl uoride contaminated groundwaters: A review of current technologies for contaminants removal

S.V. Jadhav et al. / Journal of Environmental Management 162 (2015) 306e325324

Mater. 173, 528e533.Kumar, V., Talreja, N., Deva, D., Sankararamakrishnan, N., Sharma, A., Verma, N.,

2011. Development of bi-metal doped micro- and nano multi-functional poly-meric adsorbents for the removal of fluoride and arsenic(V) from wastewater.Desalination 282, 27e38.

Kundu, S., Kavalakatt, S.S., Pal, A., Ghosh, S.K., Mandal, M., Pal, T., 2004. Removal ofarsenic using hardened paste of Portland cement: batch adsorption and columnstudy. Water Res. 38 (17), 3780e3790.

Li, J., Wang, Y., Xie, X., Su, C., 2012. Hierarchical cluster analysis of arsenic andfluoride enrichments in groundwater from the Datong basin, N. China.J. Geochem. Explor. 118, 77e89.

Li, W., Cao, C.Y., Wu, L.Y., Ge, M.F., Song, W.G., 2011. Superb fluoride and arsenicremoval performance of highly ordered mesoporous aluminas. J. Hazard. Mater.198, 143e150.

Lin, T.-F., Wu, J.-K., 2001. Adsorption of arsenite and arsenate within activatedalumina grains: equilibrium and kinetics. Water Res. 35 (8), 2049e2057.

Litter, M.I., Morgada, M.E., Bundschuh, J., 2010. Possible treatments for arsenicremoval in Latin American waters for human consumption. Environ. Pollut. 158,1105e1118.

Liu, R., Zhu, L., Gonga, W., Lan, H., Liu, H., Qu, J., 2013. Effects of fluoride on coag-ulation performance of aluminum chloride towards Kaolin suspension. Colloid.Surf. A 421, 84e90.

Luo, F., Inoue, K., 2004. The removal of fluoride ion by using metal (III)-loadedamberlite resins. Solvent Extr. Ion. Exch. 22, 305e322.

Maji, S.K., Pal, A., Pal, T., 2008. Arsenic removal from real-life groundwater byadsorption on laterite soil. J. Hazard. Mater. 2e3, 811e820.

Mak, M.S.H., Rao, P., Lo, I.M.C., 2009. Effects of hardness and alkalinity on theremoval of arsenic(V) from humic acid-deficient and humic acid-rich ground-water by zero-valent iron. Water Res. 43 (17), 4296e4304.

Malaisamy, R., Talla-Nwafo, A., Jones, K.L., 2011. Polyelectrolyte modification ofnanofiltration membrane for selective removal of monovalent anions. Sep.Purif. Technol. 77, 367e374.

Malik, A.H., Khan, Z.M., Mahmood, Q., Nasreen, S., Bhatti, Z.A., 2009. Perspectives oflow cost arsenic remediation of drinking water in Pakistan and other countries.J. Hazard. Mater. 168, 1e12.

Maliyekkal, S.M., Shukla, S., Philip, L., Indumathi, M.N., 2008. Enhanced fluorideremoval from drinking water by magnesia-amended activated alumina gran-ules. Chem. Eng. J. 140, 183e192.

Mameri, N., Lounici, H., Belhocine, D., Grib, H., Piron, D.L., Yahiat, Y., 2001.Defluoridation of Sahara water by small plant electrocoagulation using bipolaraluminium electrodes. Sep. Purif. Technol. 24, 113e119.

Nevarez, L.M., Casarrubias, L.B., Canto, O.S., Celzard, A., Fierro, V., Gomez, R.I.,Sanchez, G.G., 2011. Biopolymers-based nanocomposites: membranes frompropionated lignin and cellulose for water purification. Carbohydr. Polym. 86,732e741.

Meenakshi, Garg, V.K., Kavita, Renuka, Malik, A., 2004. Groundwater quality in somevillages of Haryana, India: focus on fluoride and fluorosis. J. Hazard. Mater. 106,85e97.

Meenakshi, R.C., Maheshwari, 2006. Fluoride in drinking water and its removal.J. Hazard. Mater. B137, 456e463.

Meenakshi, S., Viswanathan, N., 2007. Identification of selective ion-exchange resinfor fluoride sorption. J. Colloid Interf. Sci. 308, 438e450.

Miretzky, P., Cirelli, A.F., 2011. Fluoride removal from water by chitosan derivativesand composites: a review. J. Fluor. Chem. 132, 231e240.

Mittal, M., Flora, S.J.S., 2006. Effects of individual and combined exposure to sodiumarsenite and sodium fluoride on tissue oxidative stress, arsenic and fluoridelevels in male mice. Chemico Biol. Interact. 162 (2), 128e139.

Mlilo, T.B., Brunson, L.R., Sabatini, D.A., 2010. Arsenic and fluoride removal usingsimple materials. J. Environ. Eng. 136 (4), 391e398.

Mohan, D., Pittman Jr., C.U., 2007. Arsenic removal from water/wastewater usingadsorbents e a critical review. J. Hazard. Mater 142, 1e53.

Mohapatra, M., Anand, S., Mishra, B.K., Giles, D.E., Singh, P., 2009. Review of fluorideremoval from drinking water. J. Environ. Manag. 91, 67e77.

Mollah, M.Y.A., Schennach, R., Parga, J.R., Cocke, D.L., 2001. Electrocoagulation (EC)science and applications. J. Hazard. Mater. 84 (1), 29e41.

Mondal, P., Hermans, N., Tran, A.T.K., Zhang, Y., Fang, Y., Wang, X., Bruggen, B.V.,2014. Effect of physico-chemical parameters on inorganic arsenic removal fromaqueous solution using a forward osmosis membrane. J. Environ. Chem. Eng. 2(3), 1309e1316.

Nicolli, H.B., Blanco, M.C., Paoloni, J.D., Fiorentino, C.E., 2008a. Aguas subterr�aneas ymateriales de acuiferos. In: Bundschuh, J., Perez-Carrera, A., Litter, M.I. (Eds.),Distribucion del arsenico en las regiones Ibericae Iberoamericana. Ed. ProgramaIberoamericano de Ciencia y Tecnologia para el Desarrollo, Buenos Aires,Argentina, pp. 57e76.

Nicolli, H.B., Bundschuh, J., Blanco, M.C., Tujchneider, O.C., Panarello, H.O.,Dape~na, C., Rusansky, J.E., 2012. Arsenic and associated trace-elements ingroundwater from the Chaco-Pampean plain, Argentina: results from 100 yearsof research. Sci. Total Environ. 429, 36e56.

Nicolli, H.B., Tujchneider, O.C., Paris, M.C., Blanco, M.C., Barros, A.J., 2008b. Sourcesand mobility of arsenic in groudwater from centre-north plain of Santa FeProvince, Argentina. In: 2nd. Int. Congress, Arsenic in the Environment, Book ofAbstracts, pp. 75e76.

Oehmen, A., Valerio, R., Llanos, J., Fradinho, J., Serra, S., Reis, M.A.M., Crespo, J.G.,Velizarov, S., 2011. Arsenic removal from drinking water through a hybrid ionexchange membrane e coagulation process. Sep. Purif. Technol. 83, 137e143.

Onyango, M.S., Kojima, Y., Kuchar, D., Osembo, S.O., Matsuda, H., 2005. Diffusionkinetic modeling of fluoride removal from aqueous solution by charge-reversedzeolites. J. Chem. Eng. Jpn. 38, 701e710.

Onyango, M.S., Kojima, Y., Kumar, A., Kuchar, D., Kubota, M., Matsuda, H., 2006.Uptake of fluoride by Al3þ-pretreated low-silica synthetic zeolites: adsorptionequilibrium and rate studies. Sep. Sci. Technol. 41, 683e704.

Padilla, A.P., Saitua, H., 2010. Performance of simultaneous arsenic, fluoride andalkalinity (bicarbonate) rejection by pilot-scale nanofiltration. Desalination 257,16e21.

Parsa, J., Shahidi, A.E., 2010. Prediction of tidal excursion length in estuaries due tothe environmental changes. Int. J. Environ. Sci. Tech. 7 (4), 675e686.

Perminova, I.V., Karpiouk, L.A., Shcherbina, N.S., Ponomarenko, S.A., Kalmykov, St.N.,Hatfield, K., 2007. Preparation and use of humic coatings covalently bound tosilica gel for Np(V) and Pu(V) sequestration. J. Alloy. Compd. 444e445, 512e517.

Perminova, I.V., Kulikova, N.A., Zhilin, D.M., Grechischeva, N.Y., Kovalevskii, D.V.,Lebedeva, G.F., Kholodov, V.A., 2006. Mediating effects of humic substances inthe contaminated environments. Viable Methods Soil Water Pollut. Monit. 1,249e273 (Protection and Remediation, Springer).

Pinney, N., Kubicki, J.D., Middlemiss, D.S., Grey, C.P., Morgan, D., 2009. Densityfunctional theory study of ferrihydrite and related Fe-oxyhydroxides. Chem.Mater. 21, 5727e5742.

Pinon-Miramontes, M., Bautista-Margulis, R.G., Perez-Hernandez, A., 2003. Removalof arsenic and fluoride from drinking water with cake alum and a polymericanionic flocculent. Fluoride 36 (2), 122e128 (Research Report).

Pontoni, L., Fabbricino, M., 2012. Use of chitosan and chitosan-derivatives to removearsenic from aqueous solutionsda mini review. Carbohydr. Res. 356, 86e92.

Rahman, M.H., Wasiuddin, N.M., Islam, M.R., 2004. Experimental and numericalmodeling studies of arsenic removal with wood ash from aqueous streams. Can.J. Chem. Eng. 82 (5), 968e977.

Rahman, S., Kim, K., Saha, S., Swaraz, A.M., Paul, D., 2014. Review of remediationtechniques for arsenic (As) contamination: a novel approach utilizing bio-or-ganisms. J. Environ. Manag. 134, 175e185.

Ranjan, M.B., Soumen, D., Sushanta, D., De Chand, G.U., 2003. Removal of arsenicfrom groundwater using crystalline hydrous ferric oxide (CHFO). Water Qual.Res. J. Can. 38, 193e210.

Rao, M.V., Tiwari, H., 2006. Amelioration by melatonin of chromosomal anomaliesinduced by arsenic and/or fluoride in human blood lymphocyte cultures.Fluoride 39 (4), 255e260.

Ratna Kumar, P., Chaudhari, S., Khilar, K.C., Mahajan, S.P., 2006. Removal of arsenicfrom water by electrocoagulation. Chemosphere 55, 1245e1253.

Ravenscroft, P., 2007. Predicting the global extent of arsenic pollution of ground-water and its potential impact on human health. UNICEF Rep. 1e35.

Ravenscroft, P., Bramme, H., Richards, K., 2009. Arsenic Pollution: a Global Syn-thesis. Wiley-Blackwell, Oxford, UK.

Reardon, E.J., Wang, Y., 2000. A limestone reactor for fluoride removal fromwastewaters. Environ. Sci. Technol. 34, 3247e3253.

Reddy, K.J., 2007. Method for removing arsenic from water. US Patent 7,235,179 B2.Reddy, K.J., 2011. Method for removing arsenite and arsenate from water. US Patent

7,897,052 B2.Reddy, K.J., Roth, T.R., 2013. Arsenic removal from natural groundwater using cupric

oxide. Natl. Groundw. Assoc. 51 (1), 83e91.Redman, A.D., Macalady, D.L., Ahmann, D., 2002. Natural organic matter affects

arsenic speciation and sorption onto hematite. Environ. Sci. Technol. 36 (13),2889e2896.

Richards, L.A., Richards, B.S., Rossiter, H.M.A., Schafer, A.I., 2009. Impact of specia-tion on fluoride, arsenic and magnesium retention by nanofiltration/reverseosmosis in remote Australian communities. Desalination 248, 177e183.

Richards, L.A., Richards, B.S., Schafer, A.I., 2011. Renewable energy powered mem-brane technology: salt and inorganic contaminant removal by nanofiltration/reverse osmosis. J. Membr. Sci. 369, 188e195.

Richards, L.A., Vuachere, M., Schafer, A.I., 2010. Impact of pH on the removal offluoride, nitrate and boron by nanofiltration/reverse osmosis. Desalination 261,331e337.

Robins, R.G., 2006. Some Chemical Aspects Relating to Arsenic Remedial Technol-ogies. http://www.epa.gov/ttbnrmrl/ArsenicPres/78.pdf.

Robins, R.G., Singh, P., Das, R.P., 2005. Co-precipitation of arsenic with Fe(III), Al(III)and mixtures of both in a chloride system, arsenic metallurgy. In: Reddy, R.G.,Ramachandran, V. (Eds.), TMS (The Minerals, Metals & Materials Society)0e87339e585e9, pp. 113e128.

Ruixia, L., Jinlong, G., Hongxiao, T., 2002. Adsorption of fluoride, phosphate, andarsenate ions on a new type of ion exchange fiber. J. Colloid Interf. Sci. 248,268e274.

Saada, A., Breeze, D., Crouzet, C., Cornu, S., Baranger, P., 2003. Adsorption ofarsenic(V) on kaolinite and on kaoliniteehumic acid complexes: role of humicacid nitrogen groups. Chemosphere 51 (8), 757e763.

Sahli, M.A., Annouar, A., Tahaikt, S., Mountadar, M., Soufiane, A., Elmidaoui, A., 2007.Fluoride removal for underground brackish water by adsorption on the naturalchitosan and by electrodialysis. Desalination 212, 37e45.

Saitua, H., Campderr�os, M., Cerutti, S., Padilla, A.P., 2005. Effect of operating con-ditions in removal of arsenic from water by nanofiltration membrane. Desali-nation 172, 173e180.

Sehn, P., 2008. Fluoride removal with extra low energy reverse osmosis mem-branes: three years of large scale field experience in Finland. Desalination 223,73e84.

Seidel, A., Waypa, J.J., Elimech, M., 2001. Role of charge (Donnan) exclusion in

Page 20: Arsenic and fl uoride contaminated groundwaters: A review of current technologies for contaminants removal

S.V. Jadhav et al. / Journal of Environmental Management 162 (2015) 306e325 325

removal of arsenic from water by a negatively charged porous nanofiltrationmembrane. Environ. Eng. Sci. 18, 105e113.

Serbezov, A., Moore, J.D., Wu, Y., 2011. Adsorption equilibrium of water vapor onselexsorb-cdx commercial activated alumina adsorbent. J. Chem. Eng. Data 56(5), 1762e1769.

Shah, V., 2008. Emerging Environmental Technologies, vol. 1. Springer Science &Business Media, p. 108.

Sharma, V.K., Sohn, M., 2009. Aquatic arsenic: toxicity, speciation, transformations,and remediation. Environ. Int. 35, 743e759.

Shen, F., Chen, X., Gao, P., 2003. Electrochemical removal of fluoride ions from in-dustrial wastewater. Chem. Eng. Sci. 58 (3e6), 987e993.

Shih, M.C., 2005. An overview of arsenic removal by pressure-driven membraneprocesses. Desalination 172, 85e97.

Shrivastava, B.K., Vani, A., 2009. Comparative study of defluoridation technologiesin India. Asian J. Exp. Sci. 23 (1), 269e274.

Solangi, B., Memon, S., Bhanger, M.I., 2009. Removal of fluoride from aqueousenvironment by modified Amberlite resin. J. Hazard. Mater. 171, 815e819.

Solangi, B., Memon, S., Bhanger, M.I., 2010. An excellent fluoride sorption behaviorof modified amberlite resin. J. Hazard. Mater. 176, 186e192.

Song, S., Lopez-Valdivieso, A., Hernandez-Campos, D.J., Peng, C., Monroy-Fernandez, M.G., Razo-Soto, I., 2006. Arsenic removal from high-arsenic waterby enhanced coagulation with ferric ions and coarse calcite. Water Res. 40e2,364e372.

Sorkina, T.A., Polyakov, A.Y., Kulikova, N.A., Goldt, A.E., Philippova, O.I., Aseeva, A.A.,Veligzhanin, A.A., Zubavichus, Y.V., Pankratov, D.A., Goodilin, E.A.,Perminova, I.V., 2014. Nature-inspired soluble iron-rich humic compounds:new look at the structure and properties. J. Soils Sediment. 14, 261e268.

Streat, M., Hellgardt, K., Newton, N.L.R., 2008. Hydrous ferric oxide as an adsorbentin water treatment part 3: batch and mini-column adsorption of arsenic,phosphorus, fluorine and cadmium ions. Process Saf. Environ. Prot. 8621e8630.

Tahaikt, M., El Habbani, R., Ait Haddou, A., Achary, I., Amor, Z., Taky, M., Alami, A.,Boughriba, A., Hafsi, M., Elmidaoui, A., 2007. Fluoride removal from ground-water by nanofiltration. Desalination 212 (1e3), 46e53.

Tang, Y., Wang, J., Gao, N., 2010. Characteristics and model studies for fluoride andarsenic adsorption on goethite. J. Environ. Sci. 22 (11), 1689e1694.

Teychene, B., Collet, G., Gallard, H., Croue, J.P., 2013. A comparative study of boronand arsenic (III) rejection from brackish water by reverse osmosis membranes.Desalination 310, 109e114.

Thakre, D., Rayalu, S., Kawade, R., Meshram, S., Subrt, J., Labhsetwar, N., 2010.Magnesium incorporated bentonite clay for defluoridation of drinking water.J. Hazard. Mater. 180, 122e130.

Thirunavukkarasu, O.S., Viraraghavan, T., Subramanian, K.S., Tanjore, S., 2002.Organic arsenic removal from drinking water. Urban Water 4e4, 415e421.

Thompson, T., Fawell, J., Kunikane, S., Jackson, D., Appleyard, S., Callan, P., Bartram, J.,Kingston, P., 2007. Chemical Safety of Drinking Water: Assessing Priorities forRisk Management. World Health Organization, Geneva, VII.

Tian, Y., Wu, M., Liu, R., Wang, D., Lin, X., Liu, W., Ma, L., Li, Y., Huang, Y., 2011.Modified native cellulose fibersda novel efficient adsorbent for both fluorideand arsenic. J. Hazard. Mater. 185, 93e100.

Tripathy, S.S., Bersillon, J.-L., Gopal, K., 2006. Removal of fluoride from drinkingwater by adsorption onto alum-impregnated activated alumina. Sep. Purif.Technol. 50, 310e317.

Tripathy, S.S., Raichur, A.M., 2008. Abatement of fluoride from water using man-ganese dioxide-coated activated alumina. J. Hazard. Mater. 153, 1043e1051.

Tubic, A., Agbaba, J., Dalmacija, E., Ivan�cev-Tumnas, I., Damlacija, M., 2010. Removalof arsenic and natural organic matter from groundwater using ferric and alumsalts: a case study of central Banat region (Serbia). J. Environ. Sci. Health A 45,

363e369.Urbano, B.F., Rivas, B.L., Martinez, F., Alexandratos, S.D., 2012. Water-insoluble

polymereclay nanocomposite ion exchange resin based on N-methyl-d-gluc-amine ligand groups for arsenic removal. React. Funct. Polym. 72e9, 642e649.

Vasudevan, S., Kannan, B.S., Lakshmi, J., Mohanraj, S., Sozhan, G., 2011. Effects ofalternating and direct current in electrocoagulation process on the removal offluoride from water. J. Chem. Technol. Biotechnol. 86, 428e436.

Villaescusa, I., Bollinger, J.C., 2008. Arsenic in drinking water: sources, occurrenceand health effects (a review). Rev. Environ. Sci. Biotechnol. 7, 307e323.

Viswanathan, N., Meenakshi, S., 2008. Effect of metal ion loaded in a resin towardsfluoride retention. J. Fluor. Chem. 129 (7), 645e653.

Viswanathan, N., Meenakshi, S., 2009. Role of metal ion incorporation in ion ex-change resin on the selectivity of fluoride. J. Hazard. Mater. 162, 920e930.

Wan, W., Pepping, T.J., Banerji, T., Chaudhari, S., Giammar, D.E., 2011. Effects of waterchemistry on arsenic removal from drinking water by electrocoagulation. WaterRes. 45 (1), 384e392.

Wang, S.-X., Wang, Z.-H., Cheng, X.-T., Li, J., Sang, Z.-P., Zhang, X.-D., Han, L.-L.,Qiao, X.-Y., Wu, Z.-M., Wang, Z.-Q., 2007. Arsenic and fluoride exposure indrinking water: children's IQ and growth in Shanyin County, Shanxi Province,China. Environ. Health Perspect. 115 (4), 643e647.

Wei, Y.-T., Zheng, Y.-M., Chen, J.P., 2011. Enhanced adsorption of arsenate onto anatural polymer-based sorbent by surface atom transfer radical polymerization.J. Colloid Interf. Sci. 356, 234e239.

WHO, 2011. Guidelines for drinking water quality. World Health Organ. 1 (4), 178.WHO/UNICEF, 2014. Progress on Drinking-water and Sanitation e 2014 Update.

World Health Organization, 1, 1.Yadanaparthi, S.K.R., Graybill, D., Wandruszka, R., 2009. Adsorbents for the removal

of arsenic, cadmium, and lead from contaminated waters. J. Hazard. Mater. 171,1e15.

Yarlagadda, S., Gude, V.G., Camacho, L.M., Pinappu, S., Deng, S., 2011. Potable waterrecovery from As, U, and F contaminated ground waters by direct contactmembrane distillation process. J. Hazard. Mater. 192, 1388e1394.

Yavuz, C.T., Mayo, J.T., Yean, S., Cong, L., Yu, W., Falkner, J., Kan, A., Tomson, M.,Colvin, V., 2006. Particle size dependence of nano-magnetite in arsenic removal.Sohn international symposium on advanced processing of metals and materials.In: Thermo and Physicochemical Principles: Special Materials and Aqueous andElectrochemical Processing, vol. 3, pp. 221e228.

Yoshizuka, K., Nishihama, S., Sato, H., 2010. Analytical survey of arsenic ingeothermal waters from sites in Kyushu, Japan, and a method for removingarsenic using magnetite. Environ. Geochem. Health 32, 297e302.

Zeni, M., Riveros, R., Melo, K., Primieri, R., Lorenzini, S., 2005. Study on fluoridereduction in artesian well-water from electrodialysis process. Desalination 185,241e244.

Zhang, Y., Dou, X.-M., Yang, M., He, H., Jing, C.-Y., Wu, Z.-Y., 2010. Removal ofarsenate from water by using an FeeCe oxide adsorbent: effects of coexistentfluoride and phosphate. J. Hazard. Mater. 179, 208e214.

Zhang, Y., Yang, M., Huang, X., 2003. Arsenic (V) removal with a Ce (IV)-doped ironoxide adsorbent. Chemosphere 51, 945e952.

Zhao, X., Zhang, B., Liu, H., Qu, J., 2011. Simultaneous removal of arsenite andfluoride via an integrated electro-oxidation and electrocoagulation process.Chemosphere 83, 726e729.

Zhilin, D.M., Schmitt-Kopplin, P., Perminova, I.V., 2004. Reduction of Cr(VI) by peatand coal humic substances. Environ. Chem. Lett. 2, 141e145.

Zuo, Q., Chen, X., Li, W., Chen, G., 2008. Combined electrocoagulation and elec-troflotation for removal of fluoride from drinking water. J. Hazard. Mater. 159,452e457.