electrochemicalcorrosionpreventioninoilfieldwastewaterfor...

Research ArticleElectrochemical Corrosion Prevention in Oilfield Wastewater forEffective Dissolved Oxygen Removal Using a Novel UpflowBioelectrochemical System

Weilin Wu

Petroleum Engineering Technology Research Institute Jiangsu Oilfield Yangzhou 225009 China

Correspondence should be addressed to Weilin Wu wuweilinjsytsinopeccom

Received 18 December 2018 Revised 10 April 2019 Accepted 20 May 2019 Published 27 June 2019

Academic Editor Wenshan Guo

Copyright copy 2019Weilin Wu(is is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Towards the corrosion issues of oilfield wastewater for water recycling the dissolved oxygen (DO) is a subsequent corrosive factorafter the air desulfurization tower for high-efficiency removal of sulfides However an in situ biological technology for efficientDO removal has not been well developed by using organics in oilfield wastewater A novel upflow bioelectrocatalytic systemassembled with three electrodes (cathode-anode-cathode) was designed in this study in which waste organic matter of oilwastewater was degraded by a bioanode for electron production and dissolved oxygen was efficiently reduced by a biocathodeunder an assistant external voltage (e results showed that the average current was kept over 6mA by applying a fixed voltage of08 V to treat oil wastewater with DO as high as 3ndash5mgL (e bottom cathode contributed the largest to DO removal ratereaching 67 contribution of the middle anode and the upper cathode for DO removal was 11 and 9 respectively (e wholeDO removal rate by the bioelectrocatalytic system was up to about 90 and the effluent DO was reduced to below 06mgL byremoving 40ndash50 COD

1 Introduction

At present for equipment corrosion pipeline blockage filtermaterial pollution and other hazards caused by sulfide in theoilfield system the air desulfurization tower with hightreatment efficiency low operating cost and convenientoperation is usually used to remove sulfides but de-sulfurization produces water with high dissolved oxygen(DO) and causes complex and rapid chemical electro-chemical and biological corrosion of the pipeline [1] Atpresent the dissolved oxygen through multistage filtrationand deoxygenation in the oilfield still reaches 05ndash08mgLwhich is much higher than the 005mgL refill water standardrequirement [2](e trace amount of dissolved oxygen causesserious chemical corrosion on water injection pipelineequipment and casing for a long time and it increases thecorrosion rate under high oxygen concentration on thesurface of steel in sediments [3] In addition dissolved oxygenoxidizes residual organic matter in the crude oil and forms afine precipitation which leads to the reduction of oil pores

and reduces the oil recovery rate At the same time the metaloxide of the metal tube wall also causes blockage of theformation and has a great influence on the permeability [4]Experiments have shown that the dissolved oxygen in wateroxidizes the polymer making the polymer chain shorter andless viscous which results in oil displacement [5] To achieveefficient DO removal before treated wastewater is reinjectedoxygen scavengers are used as chemical agents like sulphiteand hydrazine hydrate However an in situ biological tech-nology for efficient DO removal has not been well developedby using organics in oilfield wastewater

Microbial electrochemical system (MES) refers to anelectrochemical system in which an antimicrobial (anode)andor reduction (cathode) reaction is carried out on anelectrode [6] Driven by the electrode potential the bioanodein the microbial electrochemical system can efficiently oxidizeorganic matter produce reducing electrons and directly orindirectly carry out electron transfer and metabolic reactionwith the electrode Compared with the microbial fuel cell(MFC) using air cathode to reduce oxygen [7 8] MES with an

HindawiJournal of ChemistryVolume 2019 Article ID 6292509 9 pageshttpsdoiorg10115520196292509

external voltage can enrich extracellular electron transferbacteria [9] and perform more efficient cathodic reduction tovarious reductive compounds (oxidants organic azo bondsnitrobenzene etc) [10 11] (e bioelectrodes are a kind ofcompound extracellular electron transfermicroorganismwitha sustainable and efficient biocatalytic reaction system[12 13] In addition relevant research reports have also foundfunctional bacteria with special conditions such as salt tol-erance and pressure resistance in microbial electrochemicalsystems For example Parot et al isolated Halomonasaquamarina and Roseobacter from seawater-enriched nega-tive biofilms and showed oxygen reduction catalytic activity[14] It has been found that iron porphyrin adsorption me-diates oxygen reduction on the surface of the electrode

Based on the principle and structure of the microbialelectrochemical system [15 16] this study will build anefficient microbial electrochemical process to enrich andremove oxygen in accordance with the characteristics ofoilfield wastewater A three-electrode (cathode-anode-cathode) upwelling oilfield wastewater microbial electro-catalytic deaeration reactor will be adopted Under a fixedexternal voltage the brush anode is acclimated and enrichedwith a large number of extracellular electron-transportingbacteria using organics in oil wastewater (e downsidebiocathode rapidly consumes dissolved oxygen throughelectronic reduction providing an anaerobic environmentfor the subsequent bioanode and biocathode (e bioanodefacultative anaerobic microorganism can further consumeresidual dissolved oxygen in the water and increase oxygenremoval rate (e research provides a new insight to developan efficient biological technology to achieve simultaneousremoval of residual organic matter and dissolved oxygen foroil wastewater

2 Materials and Methods

21 Bioreactor Setup and Start-Up (e experimental devicewas a membrane-lessthree-electrode (cathode-anode-cathode) upflow oilfield sewage microelectrocatalyticdeoxygenation reactor with an inner diameter of 5 cm anda height of 100 cm and an effective volume of 2 L (seeFigure 1) (e anode was made of carbon brush electrode(carbon fiber radius 25 cm length 20 cm) and thecathode was made of nickel foam (Ni gt 998) (thickness5mm length 20 cm porosity 95 specific surface area09m2g) [17] (e anode and cathode were fixed in themiddle of each cylinder accordingly through titaniumwire on a plastic supporter where the distance was around5 cm between the neighbouring electrodes A 08 V aux-iliary DC voltage was applied between the anode and thecathode of the reactor to regulate the electrode potentialWastewater is poured from the bottom inlet through thetwo levels of cathode and anode where the top adopts theclassic three-phase separator design To maintain sus-pended communities during continuous flow operationoverflow was controlled by a laciniate downflow weirUsually a splitter plate is used in the middle position ofthe reactor which can lead to an even flow type with goodmixture through the long distance in cylinder reactors

(e reactor was started with the biochemical pool effluentfrom the domestic sewage treatment plant as the inoculumsource and the bioelectrode film growth and domesticationwere carried out with the acetate as the domesticated carbonsource(e domestication of the inlet is shown in Table 1(evolume ratio of inoculated wastewater and acclimated in-fluent water was 1 1 and it was cultured for 24 h at roomtemperature using the sequential batch domesticationmethod(e inoculum and the domesticated influent mixturewere replaced twice Observed by the circuit current datacollector the steady growth of the current indicated that thebioelectrode was domesticated successfully Continuous flowwater was used for continuous and stable operation for 1weekwith hydraulic retention time (HRT) of 6 h (e change ofcurrent data was monitored by an automatic data recorder inreal time (e current change can reflect the working state ofmicrobial electrocatalysis in real time [18] (e stable oper-ation process can be replaced by the actual oilfield wastewaterfor deoxygenation debugging and operation which was keptrunning for 2months (HRT 6h)

Vitamin fluid components [19] are biotin 20mg folicacid 20mg vitamin B6 100mg thiamine hydrochloride50mg riboflavin 50mg niacin 50mg calcium panto-thenate 50mg vitamin B12 01mg right aminobenzoic acid50mg lipoic acid 50mg and deionized water 10 L

Trace element liquid components [20] are C6H9NO6(nitrilotriacetic acid) 15 g MgSO4middot7H2O 30 g CaCl2 01 gMnSO4middotH2O 05 g NaCl 10 g Na2MoO4middot2H2O 001 gZnSO4middot7H2O 01 g FeSO4middot7H2O 01 g CuSO4middot5H2O 001 gCoCl2middot6H2O 01 g H3BO3 001 g KAl(SO)4) 2middot12H2O 001 gNiCl2middot6H2O 240mg Na2WO4 250mg and 10 L ofdeionized water

22 Oilfield Wastewater Oilfield wastewater was analyzedCOD 1000ndash1500mgL including small molecule volatileacid 500ndash600mgL macromolecular petroleum hydrocar-bons 300ndash400mgL ammonia nitrogen 657mgL sulfate5656mgL dissolved oxygen content 4ndash5mgL conduc-tivity 189mScm and pH 85ndash91 (e treatment watersamples are collected from the two-stage sampling ports foranalysis and the collection area is connected with a three-way valve to prevent oxygen entering

23 Measurement and Calculation Methods

231 Main Parameter Measurement (e pH temperatureand DO were measured using a portable integrated pHmeter the water sample ATP microbial activity was de-termined by an ATP instrument (GloMax 2020 Turner Bio-Systems Sunnyvale CA USA) a data logger (Model 2700Keithley) was used Instruments for real-time monitoringand recording of microbial electron transfer processes toobtain bioelectrode potential and electron transfer quantityinformation were used

232 COD Removal Calculation (e COD removal effi-ciency is an indispensable performance indicator for water

2 Journal of Chemistry

treatment equipment and the most intuitive indicator (ecalculation formula is as follows

CODR CODin minusCODout

CODintimes 100 (1)

where CODin is the chemical oxygen demand of the influentmgL CODout is the chemical oxygen demand of the effluentmgL and CODR is the COD removal efficiency [21]

233 Coulomb Efficiency Calculation Coulombic efficiency(CE) is the ratio of the actual amount of electricity (Q)generated by the anodic microbial oxidation of organicmatter to the circuit and the theoretical amount of electricitygenerated by the substratersquos own oxidation (QT) (e elec-tron recovery efficiency [22] is calculated as follows

CE QQT

times 100 (2)

When acetate is used as the substrate for the reactor theefficiency of the system can be calculated by the followingformula

(e current from the positive level to circuit is calculatedaccording to the actual current

Q It 1113946 i middot dt (3)

(e total amount of acetate is converted into the cou-lomb number of electrons that is the theoretical amount ofelectricity

QT F middot b middot m

M (4)

where F is the Faraday constant 96485Cmiddotmolminus1 b is theamount of electrons lost by 1mol of substrate conversion(acetate b 8) m is the mass of substrate consumed g M isthe molar of the substrate quality gmol

In the process of treating organic wastewater due to thecomplexity of the composition of organic wastewater it isimpossible to determine the specific reaction substance thatwill react (erefore the chemical oxygen demand (COD)consumed by the substrate is generally used to calculateQT soQ (the calculation formula of TF106) is improved as follows

QT F middot b middot CODin minusCODout( 1113857 middotV

MO2

(5)

where CODin is the chemical oxygen demand of the sub-strate at the beginning of the reaction mgL CODout is the

Water outlet

Water inlet

Connectingflange

Referenceelectrodeopenings

Splitter plate

Sample tap

Three-phase separatorTop flange

Downflow weir

Top flange

Gas-collecting tub

Gas-collecting hood

Downflow weir

(b)

(c)(a) (d)

70 115

35

115 702550

25

25

25

20

250

250

250

FlangeTitanium wireof the cathode

Cathode

250

Titanium wireof the anode Flange

Anode

250

Figure 1 (ree-electrode (cathode-anode-cathode) upflow bioelectrochemical deoxygenation reactor (a) the reactor design (b) the topoutlet weir design (c) the cathode design (d) the anode design

Table 1 Formula of inlet water for reactor start-up

Substance Acetate Disodium hydrogen phosphatedodecahydrate

Sodium dihydrogenphosphate dihydrate

Ammoniumchloride

Potassiumchloride Vitamin Trace

elementConcentration 150 gL 1155 gL 277 gL 031 gL 013 gL 1 mLL 1 mLL

Journal of Chemistry 3

chemical oxygen demand of the substrate after the end of thereaction mgL V is the volume of the reaction solution LMO2

is the molar mass of organic matter based on oxygen32 gmol and b is the number of electrons transferred byoxidation of 1mol of organic matter with oxygen as thestandard b 4

3 Results and Discussion

31 Start and Run of 6ree-Electrode Biological CatalyticDeoxygenationReactor In order to achieve rapid start-up ofthe reactor the carbon source in the anode adopts the acetatewhich is most suitable for the growth of extracellularelectron-transporting bacteria and its water intake con-centration was about 102667plusmn 10693mgL After the start-up the reactor was after 6 h residence time (e CODconcentration of the effluent was about 61333plusmn 1193mgLand the removal rate was 4065plusmn 58 (see Figure 2) in-dicating that the biofilm was basically formed during thisstage According to the amount of COD utilized and theamount of extracellular electron transport the Coulombicefficiency of the growth process of the extracellular electron-transporting bacteria of the anode biofilm was calculated tobe 5 (e coulomb efficiency of the positive level indicatesthat the acetic acid salt was passed on to the positive levelthrough the respiration of microorganisms and the elec-trons generated by oxidation are transferred to the anodethrough the extracellular electron transport system of themicroorganism (erefore the Coulombic efficiency in-dicated that the anode had successfully domesticated theextracellular electron-transporting bacteria

(e acclimated influent water was used under the se-quencing batch condition(e average current of the reactorcan be stable above 6plusmn 025mA and the positive potentialwas mainly stable at minus500plusmn 50mV after successful start-up(AgAgCl was the reference electrode) (see Figure 3) (epotential of the anode reflected the ability of the microor-ganism to carry out extracellular electrons transfer At thispotential the anode had the highest microbial activity andcan effectively oxidize the organic matter for extracellularelectron transfer [19 23] At the same time the potential alsoindicated that the dissolved oxygen in the medium envi-ronment near the anode had been exhausted [24]

32 Removal Efficiency of Dissolved Oxygen in the OilfieldWastewater

321 Removal Contribution of Every Electrode on DissolvedOxygen In order to specifically study the oxygen-scavenging capacity of each electrode unit the dissolvedoxygen was segmentally monitored using a mobile dissolvedoxygen meter (e content of dissolved oxygen in the waterof the oilfield was about 5plusmn 025mgL After passing throughthe first stage of the reactor (bottom of the reactor) thedissolved oxygen dropped to about 1-2mgL passingthrough the anode area of the reactor (in the middle of thereactor) (e dissolved oxygen reached about 1mgLreaching the second stage cathode (above the reactor)and the dissolved oxygen drop to 058plusmn 011mgL

(erefore the dissolved oxygen concentration of the effluentof the reactor reached 06mgL under the condition that theinfluent dissolved oxygen concentration was close to 5mgL(see Figure 4) In addition the main dissolved oxygen re-moval occurred at the cathode and the dissolved oxygenremoval effect on the anode was the lowest and the overalldissolved oxygen removal rate was close to 8835plusmn 2

(e ATP activity was used to directly measure the mi-crobial activity in the solution (e results showed that themicrobial activity in the reactor was similar at 179mgL whenthe water was oilfield wastewater according to the number ofATP contained in a single cell (175times10minus10 nmol ATPcell)the result was converted into the number of cells and thenumber of cells in the reactor solution was about 713times108Compared with the number of microbial cells (1011) whenusing acetate as a substrate the difference was relatively largeand the difference was close to two orders of magnitude asshown in Figure 5 (erefore the activity of microorganismswas higher when acetate was used as a substrate and themicrobial activity of the anode and cathode was rapidlydecreased when it was replaced with oilfield sewage

322 Removal Efficiency of Dissolved Oxygen (rough theoperation of a single oxygen-scavenging reactor it wasfound that the dissolved oxygen concentration in the singlereactor was less than 1mgL under the condition of dis-solved oxygen concentration of 5plusmn 025 mgL which was farbelow the 002mgL effluent compliance requirementHowever the actual oilfield wastewater had certain impacton the activity of the bioelectrode (erefore for the de-oxidation experiment of the oilfield wastewater as the carbonsource mode the two reactors were connected to form aseries process of two sets of bioelectrochemical deaerator(e influent water of the reactor was selected separately andthe positions of 1 3 and 4 and the water outlet were dis-solved oxygen-monitoring sites (e main results are shownin Figure 6

After 40 days of continuous operation the dissolvedoxygen concentrations at positions 1 3 and 4 decreased to004ndash016mgL 003ndash013mgL and 001ndash008mgL re-spectively indicating that the first cathode (No 1) was stillthe main area for deoxidation while the late position 4indicated that the second cathode can effectively ensure aresidual DO removal After the first stage of the process theDO concentration obtained at position 3 was very close tothe minimal level so the second stage process was essentialfor the effluent dissolved oxygen to reach the standard

As shown in Figure 7 the reactor was switched fromthe acetate medium to the actual oilfield wastewater in thefirst 5 days and the oxygen removal capacity was affectedAfter the adaptation the oxygen removal capacity of thereactor was gradually increased the dissolved oxygenconcentration in the influent water was maintained at thelevel of 5 plusmn 025mgL the dissolved oxygen concentrationof the effluent gradually decreased with the operation ofthe reactor and finally reached 002 plusmn 002mgL of effluent(day 54) where the dissolved oxygen removal rate wasalmost 100


(e DO removal methods for oil reinjection water aremainly divided into physical removal and chemical removalin common (e physical methods mainly include thermal

deaeration and vacuum deaeration (e thermal deaerationenergy consumption is large and the operation is difficultwhich cannot meet the requirements of deaeration in the

0

200

400

600

800

1000

1200

1400

COD

(mg

L)

Influent Effluent0

10

20

30

40

50

COD removal

COD

rem

oval

()

Figure 2 COD of the influent and effluent and COD removal rate of the effluent

Influent The firstcathode (below)

The anode(middle)

The secondcathode (top)

The wholereactor

Diss

olve

d ox

ygen

conc

entr

atio

n (m

gL)

Dissolved oxygen concentration

Diss

olve

d ox

ygen

rem

oval

rate

()

0

1

2

3

4

5

6

0

20

40

60

80

100

Figure 4 Dissolved oxygen concentration changes and removal rates at different effluent locations

Star

ting

curr

ent (

mA

)

0

2

4

6

8

1 2 3 4 50Starting time (d)

(a)

1 2 3 4 50Time (d)

ndash06

ndash04

ndash02

00

02

04

06

Pote

ntia

l (V

)

(b)

Figure 3 Starting current and anode potential versus time


oileld e equipment of vacuum deaeration needs to beinstalled on-site and is too bulky to be regulated easilyPhysical methods are seldom to be used at establishedsewage treatment stations Chemical deaeration is mainly byadding oxygen scavengers such as sodium sulte (Na2SO3)

and hydrazine hydrate (N2H4middotH2O) e latter is expensiveand highly toxic while Na2SO3 is less ecient and convertedto sulfate in the pipeline system e current study showedthat an in situ biological technology for ecient DO removalcan be developed by using organics in oileld wastewater

The firstcathode (below)

The anode(middle)


00070

00075

00080

00085

00090

00095

24262830323436384042

Cell

num

ber 1

011 co

unt

Acetate carbon source modeCarbon source mode of oilfield sewage

Figure 5 Microbial activity (number of cells)

Cathode

Anode

Cathode

Influent

Effluent

Cathode

Anode

Cathode

Influent

Effluent

1

3

4

(a)

0 9 18 27 36 45 54Time (d)

1 dissolved oxygen concentration

005

115

225

335

4

mg

L

(b)

0 9 18 27 36 45 54Time (d)


005

115

225

335

445

5

mg

L

(c)

0

05

1

15

2

25

3

35

0 9 18 27 36 45 54

mg

L

Time (d)


(d)

Figure 6 Reactor oxygenation and dissolved oxygen concentration at dierent euent locations


rough the construction of a novel three-electrode(cathode-anode-cathode) upwelling oileld wastewater mi-crobial electrocatalytic deaeration reactor the residual or-ganic matter in the oileld wastewater is further oxidized intocarbon dioxide by anode-respiring microorganisms (ARB)and the dissociative electrons are transferred to the cathodethrough the eect of extracellular electron transfer which areused for the oxygen donor therefore the oxygen is reduced towater so as to achieve the synchronous removal of oxygenand residual organic matter in the oileld wastewater

e biocathode is the key to achieving rapid oxygenremoval Cathode is one of the main factors restrictingbioelectrocatalysis Cathode can use oxygen as an electronacceptor and electron transport medium From the per-spective of oxygen reduction kinetics the oxygen reductionrate directly aects the oxygen-scavenging eciency of thereactor By adding various catalysts to the cathode to in-crease the reduction rate of oxygen the catalyst or electronconductor used has Pt transition metal elements ferricy-anide etc but there are problems such as high cost poorstability and easy catalyst contamination [25] e bio-cathode utilizes an enzyme having a specic function in themicroorganism as a catalyst to reduce operating cost im-prove reactor performance and utilize microorganismmetabolism to remove various contaminants in the water[26] e biocathode can directly take oxygen as an electronacceptor e microorganism directly transfers electrons tooxygen for oxygen reduction in addition oxygen can beindirectly used as an electron acceptor that is the micro-organism utilizes a metal oxide or a high-valent iron salt(such as dioxide) Microorganisms use the reduction ofmetal oxides or high-valent iron to achieve the transfer ofelectrons to oxygen [27]

e main factors aecting the bioelectrocatalytic de-oxygenation eciency of oxygen as electron acceptor includereactor conguration reactor volume and operating

conditions [28] Dierent congurations of bioelectrocatalyticreactors will aect the transport channels (iemembranearea) of protons inside the reactor aecting the distance ofproton transfer and the transfer of protons dierent reactorvolumes will have a certain eect on oxygen removal As thereactor volume increases some dead zones and short-owconditions occur in the reactor meanwhile large size of thereactor also increases the distance of proton transfer therebylimiting the oxygen removal eciency

4 Conclusions

(1) Using the specied formula to enter the water thethree-electrode upow reactor was successfullystarted within 5 days the average current was stableabove 6plusmn 025mA and the anode potential wasmainly stabilized at about minus500plusmn 50mV At thispotential the anode had the highest microbial ac-tivity e anode can eectively oxidize organicmatter and carry out extracellular electron transfer

(2) Under the acetate carbon source mode the downsidecathode contributed the most to the dissolved ox-ygen removal rate and the dissolved oxygen con-centration of the euent at the inuent dissolvedoxygen concentration was close to 5plusmn 025mgL Itreached 058plusmn 011mgL and the removal rate wasabout 8835plusmn 2

(3) Two three-electrode upow reactors were connectedto treat oileld wastewater and achieved a stablebioelectrochemical deoxygenation process e dis-solved oxygen concentration of the inuent wasmaintained 5plusmn 025mgL and the nal dissolvedoxygen concentrationcan reached 002plusmn 002mgLAll DO was almost removed which meets therequirements of the relling water standard

Effluent (mgL)

4 water level (mgL)1 water level (mgL) 3 water level (mgL)

Influent (mgL)

Removal rate of DO ()

The D

O co

ncen

trat

ion

of ef

fluen

t (m

gL)

0

10

20

30

40

50

60

70

80

90

100

The r

emov

al ra

te o

f DO

()

00051015202530354045505560657075

10 20 30 40 50 600Time (d)

Figure 7 Curve of dissolved oxygen concentration and dissolved oxygen removal eciency with time in dierent water outlets


Data Availability

All data were generated during the in-site measurementRaw data sharing is not applicable to this article as data wereanalyzed using EXCEL or ORIGIN in this study (e data(figure) used to support the findings of this study are in-cluded within the supplementary information file

Conflicts of Interest

(e author declares there are no conflicts of interest

Acknowledgments

We would like to acknowledge the Sinopec Jiangsu OilfieldBranch Scientific Research Project (JS16024)

Supplementary Materials

(e membrane-lessthree-electrode (cathode-anode-cathode)upflow reactor for oilfield sewage microelectrocatalytic de-oxygenation (e reactor was assembled with an inner di-ameter of 5 cm and a height of 100 cm and an effective volumeof 2 L (e anode was made of the carbon brush electrode(carbon fiber radius 25 cm length 20 cm) and the cathodewas made of nickel foam (Nigt 998) (SupplementaryMaterials)

References

[1] T Liengen R Basseguy D Feron et al UnderstandingBiocorrosion Fundamentals and Applications ElsevierAmsterdam Netherlands 2014

[2] Oil and Gas Geological Exploration Standardization Com-mittee SYT 5329-2012 Recommended Index and AnalysisMethod for Water Injection Quality of Clastic Reservoir Pe-troleum Industry Press Beijing China 2006

[3] R Xiong and W Gang ldquoCorrosion of sulfite and catalyticsulfite in steel in oxygenated waterrdquo Oilfield Chemistry vol 1pp 46ndash48 1999

[4] B Qu Y Ma and J Xie Introduction to EnvironmentalProtection of Oil and Gas Fields Petroleum Industry PressBeijing China 2009

[5] W Liu X Huang J Zhao et al ldquoCorrosion causes andprotective measures of oil wellsrdquo Corrosion Science andProtection Technology vol 18 no 6 pp 448ndash450 2006

[6] W He Y Dong C Li et al ldquoField tests of cubic-meter scalemicrobial electrochemical system in a municipal wastewatertreatment plantrdquoWater Research vol 155 pp 372ndash380 2019

[7] X ZhangW He L Ren J Stager P J Evans and B E LoganldquoCOD removal characteristics in air-cathode microbial fuelcellsrdquo Bioresource Technology vol 176 pp 23ndash31 2015

[8] H Rismani-Yazdi S M Carver A D Christy andO H Tuovinen Cathodic limitations in microbial fuel cellsan overviewrdquo Journal of Power Sources vol 180 no 2pp 683ndash694 2008

[9] W Liu A Wang S Cheng et al ldquoGeochip-based functionalgene analysis of anodophilic communities in microbialelectrolysis cells under different operational modesrdquo Envi-ronmental Science amp Technology vol 44 no 19 pp 7729ndash7735 2010

[10] B Liang H Cheng J D Van Nostrand et al ldquoMicrobialcommunity structure and function of nitrobenzene reduction

biocathode in response to carbon source switchoverrdquo WaterResearch vol 54 pp 137ndash148 2014

[11] Q Sun L Zhi-Ling L Wen-Zong et al ldquoAssessment of theoperational parameters in bioelectrochemical system inperspective of decolorization efficiency and energy conser-vationrdquo International Journal Electrochemical Science vol 11pp 2447ndash2460 2016

[12] J Hu C Zeng G Liu H Luo L Qu and R ZhangldquoMagnetite nanoparticles accelerate the autotrophic sulfatereduction in biocathode microbial electrolysis cellsrdquo Bio-chemical Engineering Journal vol 133 pp 96ndash105 2018

[13] D R Lovley ldquoSyntrophy goes electric direct interspecieselectron transferrdquo Annual Review of Microbiology vol 71no 1 pp 643ndash664 2017

[14] S Parot I Vandecandelaere A Cournet et al ldquoCatalysis ofthe electrochemical reduction of oxygen by bacteria isolatedfrom electro-active biofilms formed in seawaterrdquo BioresourceTechnology vol 102 no 1 pp 304ndash311 2011

[15] W Huang J Chen Y Hu and L Zhang ldquoEnhancement ofCongo red decolorization by membrane-free structure andbio-cathode in a microbial electrolysis cellrdquo ElectrochimicaActa vol 260 no 10 pp 196ndash203 2018

[16] T Sangeetha Z Guo W Liu et al ldquoEnergy recovery eval-uation in an up flow microbial electrolysis coupled anaerobicdigestion (ME-AD) reactor role of electrode positions andhydraulic retention timesrdquo Applied Energy vol 206pp 1214ndash1224 2017

[17] L Wang W Liu Z He Z Guo A Zhou and A WangldquoCathodic hydrogen recovery and methane conversion usingPt coating 3D nickel foam instead of Pt-carbon cloth inmicrobial electrolysis cellsrdquo International Journal of HydrogenEnergy vol 42 no 31 pp 19604ndash19610 2017

[18] Y Feng Y Zhang S Chen and X Quan ldquoEnhanced pro-duction of methane from waste activated sludge by thecombination of high-solid anaerobic digestion and microbialelectrolysis cell with iron-graphite electroderdquo Chemical En-gineering Journal vol 259 pp 787ndash794 2015

[19] S Srikanth M Kumar and S K Puri ldquoBio-electrochemicalsystem (BES) as an innovative approach for sustainable wastemanagement in petroleum industryrdquo Bioresource Technologyvol 256 pp 506ndash518 2018

[20] C Zhu H Wang Q Yan R He and G Zhang ldquoEnhanceddenitrification at biocathode facilitated with biohydrogenproduction in a three-chambered bioelectrochemical system(BES) reactorrdquo Chemical Engineering Journal vol 312pp 360ndash366 2017

[21] S M K Luma T F Lucas Z Marcelo et al ldquoUnraveling theinfluence of the CODsulfate ratio on organic matter removaland methane production from the biodigestion of sugarcanevinasserdquo Bioresource Technology vol 232 p 107 2017

[22] Y Feng Y Liu and Y Zhang ldquoEnhancement of sludgedecomposition and hydrogen production from waste acti-vated sludge in a microbial electrolysis cell with cheap elec-trodesrdquo Environmental Science Water Research amp Technologyvol 1 no 6 pp 761ndash768 2015

[23] A Bose E J Gardel C Vidoudez et al ldquoElectron uptake byiron-oxidizing phototrophic bacteriardquo Nature Communica-tions vol 5 no 3391 p 3391 2014

[24] H Muhammad I A Tahiri M Muhammad et al ldquoAcomprehensive heterogeneous electron transfer rate constantevaluation of dissolved oxygen in DMSO at glassy carbonelectrode measured by different electrochemical methodsrdquoJournal of Electroanalytical Chemistry vol 775 pp 157ndash1622016


[25] K B Liew R W D Wan M Ghasemi et al ldquoNon-Pt catalystas oxygen reduction reaction in microbial fuel cells a reviewrdquoInternational Journal of Hydrogen Energy vol 39 no 10pp 4870ndash4883 2014

[26] Z He and L Angenent ldquoApplication of bacterial biocathodesin microbial fuel cellsrdquo Electroanalysis vol 18 no 19-20pp 2009ndash2015 2006

[27] M Rimboud M Barakat A Bergel and B Erable ldquoDifferentmethods used to form oxygen reducing biocathodes lead todifferent biomass quantities bacterial communities andelectrochemical kineticsrdquo Bioelectrochemistry vol 116pp 24ndash32 2017

[28] L Zhang Research on Factors Affecting Electricity Productionand Sewage Purification of Biocathode Microbial Fuel CellsChongqing Technology and Business University ChongqingChina 2010


TribologyAdvances in

Hindawiwwwhindawicom Volume 2018


International Journal ofInternational Journal ofPhotoenergy


Journal of

Chemistry


Advances inPhysical Chemistry

Hindawiwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of


NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Applied ChemistryJournal of



Biochemistry Research International


Enzyme Research


Journal of

SpectroscopyAnalytical ChemistryInternational Journal of


MaterialsJournal of



BioMed Research International Electrochemistry

International Journal of


Na

nom

ate

ria

ls


Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

external voltage can enrich extracellular electron transferbacteria [9] and perform more efficient cathodic reduction tovarious reductive compounds (oxidants organic azo bondsnitrobenzene etc) [10 11] (e bioelectrodes are a kind ofcompound extracellular electron transfermicroorganismwitha sustainable and efficient biocatalytic reaction system[12 13] In addition relevant research reports have also foundfunctional bacteria with special conditions such as salt tol-erance and pressure resistance in microbial electrochemicalsystems For example Parot et al isolated Halomonasaquamarina and Roseobacter from seawater-enriched nega-tive biofilms and showed oxygen reduction catalytic activity[14] It has been found that iron porphyrin adsorption me-diates oxygen reduction on the surface of the electrode

Based on the principle and structure of the microbialelectrochemical system [15 16] this study will build anefficient microbial electrochemical process to enrich andremove oxygen in accordance with the characteristics ofoilfield wastewater A three-electrode (cathode-anode-cathode) upwelling oilfield wastewater microbial electro-catalytic deaeration reactor will be adopted Under a fixedexternal voltage the brush anode is acclimated and enrichedwith a large number of extracellular electron-transportingbacteria using organics in oil wastewater (e downsidebiocathode rapidly consumes dissolved oxygen throughelectronic reduction providing an anaerobic environmentfor the subsequent bioanode and biocathode (e bioanodefacultative anaerobic microorganism can further consumeresidual dissolved oxygen in the water and increase oxygenremoval rate (e research provides a new insight to developan efficient biological technology to achieve simultaneousremoval of residual organic matter and dissolved oxygen foroil wastewater

2 Materials and Methods

21 Bioreactor Setup and Start-Up (e experimental devicewas a membrane-lessthree-electrode (cathode-anode-cathode) upflow oilfield sewage microelectrocatalyticdeoxygenation reactor with an inner diameter of 5 cm anda height of 100 cm and an effective volume of 2 L (seeFigure 1) (e anode was made of carbon brush electrode(carbon fiber radius 25 cm length 20 cm) and thecathode was made of nickel foam (Ni gt 998) (thickness5mm length 20 cm porosity 95 specific surface area09m2g) [17] (e anode and cathode were fixed in themiddle of each cylinder accordingly through titaniumwire on a plastic supporter where the distance was around5 cm between the neighbouring electrodes A 08 V aux-iliary DC voltage was applied between the anode and thecathode of the reactor to regulate the electrode potentialWastewater is poured from the bottom inlet through thetwo levels of cathode and anode where the top adopts theclassic three-phase separator design To maintain sus-pended communities during continuous flow operationoverflow was controlled by a laciniate downflow weirUsually a splitter plate is used in the middle position ofthe reactor which can lead to an even flow type with goodmixture through the long distance in cylinder reactors

(e reactor was started with the biochemical pool effluentfrom the domestic sewage treatment plant as the inoculumsource and the bioelectrode film growth and domesticationwere carried out with the acetate as the domesticated carbonsource(e domestication of the inlet is shown in Table 1(evolume ratio of inoculated wastewater and acclimated in-fluent water was 1 1 and it was cultured for 24 h at roomtemperature using the sequential batch domesticationmethod(e inoculum and the domesticated influent mixturewere replaced twice Observed by the circuit current datacollector the steady growth of the current indicated that thebioelectrode was domesticated successfully Continuous flowwater was used for continuous and stable operation for 1weekwith hydraulic retention time (HRT) of 6 h (e change ofcurrent data was monitored by an automatic data recorder inreal time (e current change can reflect the working state ofmicrobial electrocatalysis in real time [18] (e stable oper-ation process can be replaced by the actual oilfield wastewaterfor deoxygenation debugging and operation which was keptrunning for 2months (HRT 6h)

Vitamin fluid components [19] are biotin 20mg folicacid 20mg vitamin B6 100mg thiamine hydrochloride50mg riboflavin 50mg niacin 50mg calcium panto-thenate 50mg vitamin B12 01mg right aminobenzoic acid50mg lipoic acid 50mg and deionized water 10 L

Trace element liquid components [20] are C6H9NO6(nitrilotriacetic acid) 15 g MgSO4middot7H2O 30 g CaCl2 01 gMnSO4middotH2O 05 g NaCl 10 g Na2MoO4middot2H2O 001 gZnSO4middot7H2O 01 g FeSO4middot7H2O 01 g CuSO4middot5H2O 001 gCoCl2middot6H2O 01 g H3BO3 001 g KAl(SO)4) 2middot12H2O 001 gNiCl2middot6H2O 240mg Na2WO4 250mg and 10 L ofdeionized water

22 Oilfield Wastewater Oilfield wastewater was analyzedCOD 1000ndash1500mgL including small molecule volatileacid 500ndash600mgL macromolecular petroleum hydrocar-bons 300ndash400mgL ammonia nitrogen 657mgL sulfate5656mgL dissolved oxygen content 4ndash5mgL conduc-tivity 189mScm and pH 85ndash91 (e treatment watersamples are collected from the two-stage sampling ports foranalysis and the collection area is connected with a three-way valve to prevent oxygen entering

23 Measurement and Calculation Methods

231 Main Parameter Measurement (e pH temperatureand DO were measured using a portable integrated pHmeter the water sample ATP microbial activity was de-termined by an ATP instrument (GloMax 2020 Turner Bio-Systems Sunnyvale CA USA) a data logger (Model 2700Keithley) was used Instruments for real-time monitoringand recording of microbial electron transfer processes toobtain bioelectrode potential and electron transfer quantityinformation were used

232 COD Removal Calculation (e COD removal effi-ciency is an indispensable performance indicator for water




CODintimes 100 (1)



CE QQT

times 100 (2)






M (4)




MO2

(5)


Water outlet

Water inlet

Connectingflange


Splitter plate

Sample tap


Downflow weir

Top flange

Gas-collecting tub

Gas-collecting hood

Downflow weir

(b)

(c)(a) (d)

70 115

35

115 702550

25

25

25

20

250

250

250


Cathode

250


Anode

250





Ammoniumchloride



















0

200

400

600

800

1000

1200

1400

COD

(mg

L)

Influent Effluent0

10

20

30

40

50

COD removal

COD

rem

oval

()



The anode(middle)


The wholereactor

Diss

olve

d ox

ygen

conc

entr

atio

n (m

gL)


Diss

olve

d ox

ygen

rem

oval

rate

()

0

1

2

3

4

5

6

0

20

40

60

80

100


Star

ting

curr

ent (

mA

)

0

2

4

6

8


(a)

1 2 3 4 50Time (d)

ndash06

ndash04

ndash02

00

02

04

06

Pote

ntia

l (V

)

(b)






The anode(middle)


00070

00075

00080

00085

00090

00095

24262830323436384042

Cell

num

ber 1

011 co

unt



Cathode

Anode

Cathode

Influent

Effluent

Cathode

Anode

Cathode

Influent

Effluent

1

3

4

(a)

0 9 18 27 36 45 54Time (d)


005

115

225

335

4

mg

L

(b)

0 9 18 27 36 45 54Time (d)


005

115

225

335

445

5

mg

L

(c)

0

05

1

15

2

25

3

35

0 9 18 27 36 45 54

mg

L

Time (d)


(d)







4 Conclusions




Effluent (mgL)


Influent (mgL)


The D

O co

ncen

trat

ion

of ef

fluen

t (m

gL)

0

10

20

30

40

50

60

70

80

90

100

The r

emov

al ra

te o

f DO

()

00051015202530354045505560657075

10 20 30 40 50 600Time (d)



Data Availability




Acknowledgments




References





































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls






CODintimes 100 (1)



CE QQT

times 100 (2)






M (4)




MO2

(5)


Water outlet

Water inlet

Connectingflange


Splitter plate

Sample tap


Downflow weir

Top flange

Gas-collecting tub

Gas-collecting hood

Downflow weir

(b)

(c)(a) (d)

70 115

35

115 702550

25

25

25

20

250

250

250


Cathode

250


Anode

250





Ammoniumchloride



















0

200

400

600

800

1000

1200

1400

COD

(mg

L)

Influent Effluent0

10

20

30

40

50

COD removal

COD

rem

oval

()



The anode(middle)


The wholereactor

Diss

olve

d ox

ygen

conc

entr

atio

n (m

gL)


Diss

olve

d ox

ygen

rem

oval

rate

()

0

1

2

3

4

5

6

0

20

40

60

80

100


Star

ting

curr

ent (

mA

)

0

2

4

6

8


(a)

1 2 3 4 50Time (d)

ndash06

ndash04

ndash02

00

02

04

06

Pote

ntia

l (V

)

(b)






The anode(middle)


00070

00075

00080

00085

00090

00095

24262830323436384042

Cell

num

ber 1

011 co

unt



Cathode

Anode

Cathode

Influent

Effluent

Cathode

Anode

Cathode

Influent

Effluent

1

3

4

(a)

0 9 18 27 36 45 54Time (d)


005

115

225

335

4

mg

L

(b)

0 9 18 27 36 45 54Time (d)


005

115

225

335

445

5

mg

L

(c)

0

05

1

15

2

25

3

35

0 9 18 27 36 45 54

mg

L

Time (d)


(d)







4 Conclusions




Effluent (mgL)


Influent (mgL)


The D

O co

ncen

trat

ion

of ef

fluen

t (m

gL)

0

10

20

30

40

50

60

70

80

90

100

The r

emov

al ra

te o

f DO

()

00051015202530354045505560657075

10 20 30 40 50 600Time (d)



Data Availability




Acknowledgments




References





































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls



















0

200

400

600

800

1000

1200

1400

COD

(mg

L)

Influent Effluent0

10

20

30

40

50

COD removal

COD

rem

oval

()



The anode(middle)


The wholereactor

Diss

olve

d ox

ygen

conc

entr

atio

n (m

gL)


Diss

olve

d ox

ygen

rem

oval

rate

()

0

1

2

3

4

5

6

0

20

40

60

80

100


Star

ting

curr

ent (

mA

)

0

2

4

6

8


(a)

1 2 3 4 50Time (d)

ndash06

ndash04

ndash02

00

02

04

06

Pote

ntia

l (V

)

(b)






The anode(middle)


00070

00075

00080

00085

00090

00095

24262830323436384042

Cell

num

ber 1

011 co

unt



Cathode

Anode

Cathode

Influent

Effluent

Cathode

Anode

Cathode

Influent

Effluent

1

3

4

(a)

0 9 18 27 36 45 54Time (d)


005

115

225

335

4

mg

L

(b)

0 9 18 27 36 45 54Time (d)


005

115

225

335

445

5

mg

L

(c)

0

05

1

15

2

25

3

35

0 9 18 27 36 45 54

mg

L

Time (d)


(d)







4 Conclusions




Effluent (mgL)


Influent (mgL)


The D

O co

ncen

trat

ion

of ef

fluen

t (m

gL)

0

10

20

30

40

50

60

70

80

90

100

The r

emov

al ra

te o

f DO

()

00051015202530354045505560657075

10 20 30 40 50 600Time (d)



Data Availability




Acknowledgments




References





































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls







The anode(middle)


00070

00075

00080

00085

00090

00095

24262830323436384042

Cell

num

ber 1

011 co

unt



Cathode

Anode

Cathode

Influent

Effluent

Cathode

Anode

Cathode

Influent

Effluent

1

3

4

(a)

0 9 18 27 36 45 54Time (d)


005

115

225

335

4

mg

L

(b)

0 9 18 27 36 45 54Time (d)


005

115

225

335

445

5

mg

L

(c)

0

05

1

15

2

25

3

35

0 9 18 27 36 45 54

mg

L

Time (d)


(d)







4 Conclusions




Effluent (mgL)


Influent (mgL)


The D

O co

ncen

trat

ion

of ef

fluen

t (m

gL)

0

10

20

30

40

50

60

70

80

90

100

The r

emov

al ra

te o

f DO

()

00051015202530354045505560657075

10 20 30 40 50 600Time (d)



Data Availability




Acknowledgments




References





































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls








4 Conclusions




Effluent (mgL)


Influent (mgL)


The D

O co

ncen

trat

ion

of ef

fluen

t (m

gL)

0

10

20

30

40

50

60

70

80

90

100

The r

emov

al ra

te o

f DO

()

00051015202530354045505560657075

10 20 30 40 50 600Time (d)



Data Availability




Acknowledgments




References





































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




Data Availability




Acknowledgments




References





































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls














Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




electrochemicalcorrosionpreventioninoilfieldwastewaterfor...

Documents