Defluoridation Of Drinking WaterMerits of Alternative Technologies

A. K. Susheela

Defluoridation of drinking waterin fluorosis-endemic areas is part ofthe National Programme for provisionof safe drinking water. Fifteen out of 30states and Union Territories of the In­dian Republic are considered endemicfor fluorosis and the defluoridationprogramme attempts to correct thissituation.

The crippling malady of fluorosisnot only affects the bones and teeth,but every tissue and organ of the body,leading to death after prolonged ill­ness. It is a problem of public healthimportance. Although the disease hadbeen known to exist in India as early asthe 1930s it was not identified as anational health problem till India be­came independent. Perhaps the mag­nitude of the problem and the possiblemethods of preventing it were not ap­preciated till recently (1986) when theGovernment of India launched a "Tech­

nology Mission on Safe Drinking Wa­ter". One of the thrust areas of this

Mission is to control and preventfluorosis. Provision of safe drinkingwater, and creating awareness amongpeople of the dangers of excess fluo­ride in drinking water have now as­sumed an important place in thisprogramme.

Population overgrowth necessi­tating augmentation of the water sup­ply, indiscriminate digging of tubewells for exploiting ground watersources, total unawareness of the im­portance of water quality analysis priorto human consumption, and continuedingestion of fluoride in excess throughdrinking water have all contributed tothe spread of the disease in recentyears.

The central problem is the identi­fication of a feasible technique for theremoval offluoride from drinking water.The technique must be suited to therural setting and must ensure sustainedavailability of safe drinking water. It isin this context that a proper examina­tion of the merits of alternative tech­

nologies available for defluoridation ofwater becomes necessary.

In this report the merits of alterna­tive technologies available for re­moval of fluoride from drinking watersources are considered.

1. NALGONDA TECHNOLOGY

USING LIME AND ALUM

Since the early 1960s the Na­tional Environmental Engineering Re­search Institute (NEERI), Nagpur, hasbeen involved in research and devel­

opment activities on defluoridation ofwater. One of the technologies whichhas been successfully translated fromthe laboratory to the field is the NalgondaTechnology. The first CommunityDefluoridation Plant for Removal of Fluo­

ride from Drinking Water was erectedin the district of Nalgonda in AndhraPradesh at Kathri town, and, so thename of the technology:

In this techonology, raw water ismixed with adequate lime and alum.The dose of lime depends upon thealkalinity of the raw water. If the rawwater has adequate alkalinity, the ad­dition of lime is not required. Alumsolution is added after the addition of

lime, stirred gently for 10 minutes andthe floes formed are allowed to settle.

This process of floc formation andsettling normally requires an hour. Inrural areas where the people practisedomestic defluoridation, the advicegiven is to mix the water with lime andalum and leave it overnight, so that thenext morning the clean supernatant isdecanted for use and is safe for con­

sumption.

In the Nalgonda technique, be­sides fluoride, turbidity, colour, odour,pesticides and organic substances, ifany, are also removed. Bacterial con­tamination is also reduced significantly.

The addition of lime or sodium

carbonate ensures adequate-alkalinityfor effective hydrolysis of aluminiumsulphate to aluminium hydroxide ( thatis, floc formation) and as a result, alu­minium does not remain in the treatedwater.

Merits: It can be used both at

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domestic and community levs:::>.• Operations are possible manually.• The chemicals are the same as those

used in municipal/urban water supplyschemes.• It is cost effective.

• A variety of designs and models havealready been developed by NEERI fOIuse in different locations.• There is considerable flexibility indesign considerations, therefore loca­tion specific alterations are possible.• Defluoridated water meets with thE

standards laid down by the Bureau 01

Indian Standards, that is, the fluoridEcontent in water shall be lower than 1ppm.

Drawbacks: The technology i~excellent, provided the daily opera·tions are entrusted to a trained, con­scientious operator. It is important thaithe doses of alum and lime are deter­

mined after assessing the fluoride con·tent and alkalinity of the raw water. It i~mandatory thatthis dose is re-assessecduring extreme summer and in thErainy season, when fluoride concen·tration and alkalinity of the water arElikely to alter. The operator should alscbe familiar with the speed of mixing,stirring the alum water, that it should bEgentle so that the chemicals are ad·equately mixed, allowed to stand fOIone hour for the floc formation anc

settling. Experience shows that if thEalum mixing is carried out at a greatelvelocity there are less chances of flocformation and a greater quantity 01

alum will be required for removal 01

fluoride which may result in residualaluminium in water.

The major cause for concern wittthe lime and alum technology is thaiif the dose of alum is not adhered to

there is a possibility of excess alumi·nium contaminating the water. ThEmaximum contamination of alumi·

nium permitted is 0.03 mg - 0.2 mgllitreof water according to 81S, as an ex·cess is suspected to cause Alzheimer'~disease.

Aluminium compounds are useefor treatment of drinking water suppl~all over the world. Because of the con­

cern shown about aluminium causin£health hazards, alternative coagLilant~and coagulant aids are now being rec·ommended.

Aluminium compounds were firs!used in the form of simple salts, that is

aluminium sulphate or aluminium chlo­ride. Later, during the 1970s,prehydrolysed salts known as basicaluminium polychlorosulphates (PACS)or basic aluminium polychlorides (PAC)were introduced. These second gen­eration products have flocculant prop­erties and could be used without floc­cu!ation additives. They also have anadvantage over simple aluminium saltsthat they are active in a wide pH range,but chances of residual aluminium in

drinking water, depending upon rawwater quality, exist. For drinking water,use of aluminium salt coagulants at theclarification stage sometimes necessi­tates a prior stage of pH adjustment(normally acidification) in orderto meetthe WHO standard for aluminium, thatis, 200 ug/litre of water.

A third generation of aluminiumsalts has now appeared. These have

high basicity or more exactly a hi.ghOH-/aluminium ratio, more than 2, whichlimits the aluminium residue while main­

taining excellent flocculation proper­ties. The high basicity aluminiumpolychlorosulphates (HB PACS) arealso extremely stable with time.

While third generation chemicalsare being used in watertreatment plantsin the WesHor reducing residual alumi­nium, in India first generation chemi­cals are still being used for water treat­ment and for removal of fluoride in theNalgonda Technology.

2. DEFLUORIDATION OF WATER

USING BONE CHARDefluoridation of drinking water

using primarily bone char was devel­oped by the Intercountry Centre forOral Health (ICOH) Chiangmai, DentalFaculty of Chulalongkoran University,Bangkok and WHO.ICOH defluoridationis based on the filtration and absorp­tion principle and uses charcoal andcharred bone meal. The defluoridationcolumn (75 cm long and 9 cm in diam­eter) has a tap at the bottom and a capwith a small hole for intake of water atthe top. The column is packed with 300gm of crushed charcoal (the bottomlayer) for absorbing colour and odour.A middle layer of 1,000 gm of charredbone meal and a top layer of approxi­mately 200 gm of clean pebbles areadded to prevent the bone meal fromfloating. The bone meal is of 40-60mesh size, obtained or produced byburning bone to an approximate tem-

perature of 600°C for 20 minutes.

Flouride contaminated raw water

is siphoned to the top of the defluoridatorat a flow rate of 4 litres/hour. Thedefluoridated water is collected into a

jar from the lower end Of.the columnwith the help of a tap.The filter, accord­ing to those who developed the sys­tem remains active for one to threemo~ths, depending on the fluoride lev­els and the amount of water consumed.

In this procedure 15-20 Iitres ofwater is initially passed through thecolumn (defluoridator), and discarded,afterwhich the water is odourless, cleanand ready for human consumption. The

question that emerges in t~e Indiancontext is: can we regularly discard 15­20 lit res of water every time for runningthrough the column to eliminate thefoul odour of the water due to the charredbone fat?

The lOCH defluoridation is beingimplemented in certain villages ofNalgonda district of Andhra Pradesh,under a project sponsored by the WHO.There was initial reluctance to use thewater treated with burned bone. A ma­jor issue which is likely to emerge is ofthe acceptability of water by vegetar­ians.

As the procedure for eliminationof fluoride using bone char is simple,inexpensive, and the operation and main­tenance do not pose problems, per­haps certain sections of the populationwho are non-vegetarians may acceptthe water without hesitation. If so, thetechnology could be promoted in selectareas, but it seems doubtful that thistechnology will be generally accepted.

3.PRASANTITECHNOLOGYUSING ACTIVATED ALUMINA

The Prasanti technology for fluo­ride removal using activated aluminapresently being used for waterdefluoridation in Indian villages, origi­nated.as a result of research and devel­opment activities carried out at the Bio­science Department at Satya Sai Uni­versity for Higher Learning at PrasantiNilayam at Anantpur District in AndhraPradesh.

Research and development ac­tivitiesin the use and effectiveness ofactivated alumina fordefluoridation havealso been carried out in different insti­

tutions in recent years.

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Alumina (that is, aluminium oxideAI 0 ) is practically insoluble in water.

The 3solubility in acid and alkali d~­pends upon previous heat treatment; Itis scarcely attacked by strong reagents.

Alumina needs to be activated for t~edefluoridation process. There are dif­

ferent grades of activated alumina. in­digenously available at a very nominalcost. The suitability of the grade fordefluoridation depends upon the porocityand surface area of the alumina. There

are other parameters which are also ~fimportance, that is, the lif~ of ~he acti­vated alumina for defluondatlon pur­

poses. A simple procedur~ for regen­eration is bound to emerge In course oftime as the Mission would still supportR & D activities in the field for perfect­

ing the technology. There is a~plescope for R & D in design and fabnca­tion to achieve cost effectiveness.

Using the activated alumina tech­

nology, both community defl~ori?ati~nplants and domestic defluondatlon fil­ters have been popularised by a com­mercial firm in the country.

The activated alumina plants canbe attached either to handpumps orstandposts in the village dependingupon the source of drinking water.

Twenty-five community defluori­dation plants, each serving approxi­mately 200-400 people in a location,have been functioning satisfactorily sincelast year. Each plant costs approxi­mately Rs 35,000. The regenerationand servicing of the plant is being car­ried out by the firm itself at an intervalof one month (depending upon the waterdrained through the plant), at a cost ofRs 350 per servicing and regenerationof the alumina which is also being metpresently through Government funds.

Besides the communitydefluoridation plants, approximately500 domestic defluoridation filters arebeing used by people living in endemicareas forfluorosis. Each stainless steeldomestic filter costs Rs 1,300-1,700depending upon the number of con­tainers in the filter system, that iS,one,two or three and the volume of thecontainer, that is, 6, 10, 18, or 27 litrecapacity. In the filter system, the unitwhich is sealed with activated alumina

is exchangeable for a new one for re­generation purposes for a very nominalcharge, when a specific volume of wa­ter is defluoridated by the user.

One gratifying finding is that thedefluoridated water quality is beingmonitored by the firm at frequent inter­vals and the records available reveal

that the quality of the output water isadhering to BIS standar-ds. It is alsonoteworthy that those who are usingthe defluoridated water specially fromthe activated alumina plants, show evi­dence of improvement of their condi­tion even within a short period of a fewweeks. As a result this technology isnow gaining acceptance.

While on the one hand, agenciesconcerned with the provision of safewater are thus struggling to minimisefluoride intake in endemic areas, thereare others who,in blind imitation of prac­tises in vogue in countries not besetwith the fluorosis problem, wish to pro­mote unrestricted use of fluoridatedtoothpastes and mouth-rinses even inendemic states. Toothpastes are nowincreasingly being used by poor popu­lations even in rural areas. Fluoridatedtoothpastes in fluoride endemic areasjust do not make sense, indeed theycould be a disservice. It is to be hopedthat sensible decfsions in this regardwill not be delayed.

The author is coordinator for the sub-mission"Control of Fluorosis", National Drinking Water Mis·sion. Government of India, and Professor ofHistocytochemistry at the AI/India Institute of MedicaiSciences, New Delhi.

References

1. Packham, R.F. and Ratnayaka, 0.0 .. (1992). Water Clarifica­tion with Aluminium Coagulants in the United Kingdom. In theproceedings of the international workshop on "Aluminium inDrinking Water", 37-49.2. Phantumvanit, P., Songpaisan, Y., and Moller, I.J.: (1988). ADefluoridator for Individual Househoid; Appropriate Technology.In World Health Forum, Vol. 9, 555-558.

3. Rao, V.K. and Mahajan, C.L.: (1988). Defluoridation of Drink­ing Water in Developing Countries - Alternative and InnovativeTechnologies. In proceedings of the 20th Mid Atlantic IndustrialWater Conference. Silver Spring. M.D. USA, p55-64.4. Bulusu, K.R. and Nawalakhe, W.G.: (1992). Defluoridation ofWater with Activated Alumina, Continuous Contacting System.Indian J. Environ H/lh, Vol. 32 NO.3, 197-218.

5. Patil, A.R. and Kulkarni, B.M.: (1991). Study of Ion ExchangeResin and Activated Alumina as Defluoridating Media. Pre­sented at the seminar on "Problems of Fluorosis", Institute ofSocial Science. New Delhi. Oct 4-15, 1991.6. Susheela, A.K., Das, T.K. Gupta, I.P., Tandon, R.K., Kacker,

S.K., Ghosh. P. and Deka, R.C.: (1992). Fluoride Ingestion andits Correlation with Gastro-intestinal Discomfort. Fluoride, Vol.

25(1),7-12.

We are grateful to UNICEF fora matching grant towards the

cost of this publication.

FOUNDATIONNEWS

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Dr 0.8. Jelliffe

The passing away of Dr O.B.Jelliffe in Los Angeles on March18 is a sad blow to the wond ofpaediatrics and nutrition. DickJelliffe was a dominant figure inthe field of Child Health for nearlyfour decades. The several books

he had authored have had a pro­found impact on paediatricians and

.nutrition scientists all around theglobe. His sustained campaign forthe promotion of breast-feeding hasbeen a major contribution.

His years of work in the coun­tries of the Carribean, Africa, andin India, inthemostformativephaseof his illustrous career had givenhim first-hand knowledge and ex­perience of the problems of theThird Wond. He was a visitingProfessor at the All India Institute

of Hygiene and Public Health,Calcutta, in the 1950s, and hadea med a very wide circle of friendsand admirers among Indianpaediatricians and nutrition scien­tists. He gave the first of the seriesof Annual Orations of the NutritionSociety of India.

Dr Jelliffe's success was not alittle due to the strong and sus­tained support of his vivacious wife- Patrice Jelliffe. The "insepa­rable Jelliffes " had enlivened sev­

eral major international paediatricand nutrition meets of the last threedecades. The numerous friendsand admirers of the Jelliffes aroundthe wond will ardently wish that'Patrice Jelliffe, a distinguishedworker in nutrition in her own right,will continue her good work in theyears ahead with undiminishedzeal.

C:Gopalan