Research Article Optimization and Modelling of Chemical ...

Hindawi Publishing CorporationJournal of ChemistryVolume 2013 Article ID 930352 8 pageshttpdxdoiorg1011552013930352

Research ArticleOptimization and Modelling of Chemical OxygenDemand Removal by ANAMMOX Process Using ResponseSurface Methodology

Ali Jalilzadeh12 Ramin Nabizadeh12 Alireza Mesdaghinia12 Aliakbar Azimi3

Simin Nasseri12 Amir Hossein Mahvi12 and Kazem Naddafi12

1 Department of Environmental Health Engineering School of Public Health Tehran University of Medical SciencesPO Box 14155-6446 Tehran Iran

2 Centre for Environmental Research Tehran University of Medical Sciences Tehran Iran3Department of Environmental Engineering Graduate School of the Environment University of Tehran Tehran Iran

Correspondence should be addressed to Ramin Nabizadeh rnabizadehtumsacir

Received 4 May 2013 Accepted 18 July 2013

Academic Editor Athanasios Katsoyiannis

Copyright copy 2013 Ali Jalilzadeh et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

A systematic model for chemical oxygen demand (COD) removal using the ANAMMOX (Anaerobic AMMonium OXidation)process was provided based on an experimental design At first the experimental data was collected from a combined biologicalaerobicanaerobic reactor For modelling and optimization of COD removal the main parameters were considered such as CODloading ammonium pH and temperature From the models the optimum conditions were determined as COD 975mgLammonium concentration equal to 2875mg-NL pH 772 and temperature 313∘C Finally the analysis of the optimum conditionsperformed by the response surface method predicted COD removal efficiency of 8107 at the optimum condition

1 Introduction

The Anaerobic AMMonium OXidation (ANAMMOX) pro-cess is introduced as a novel and low cost alternative toconventional nitrogen removal systems to treat nitrogenouscompounds [1] Van de Graaf evaluated the pathway ofmetabolic Candidatus Brocadia anammoxidans and Stroussuggested a different metabolic course for the nitrogencycle In both studies hydrazine was the most importantintermediate [2ndash4]

Detection studies of 16S rDNA sequences demonstratedthat the planctomycete bacteria such as Brocadia anammox-idans Kuenenia stuttgartiensis are found in ANAMMOXconditions [5]

ANAMMOX bacteria oxidize ammonium under anoxicconditions and in this reaction nitrite acts as the electronacceptor based on the following equation [1]

NH4

+

+ 132NO2

minus

+ 0066HCO3

minus

+ 013H+

997888rarr 0066CH2O05N015+ 102N

2

+ 026NO3

minus

+ 203H2O

(1)

During the ANAMMOX process the highest removalefficiency of ammonium and nitrite was up to 97 and98 respectively [6] Molinuevo showed that ANAMMOXand denitrification always occurred simultaneously meaningthat both processes could coexist in the same environ-ment [7] They mentioned that environmental conditionssuch as COD nitrite nitrate ammonium pH and tem-perature have to be controlled to provide the appropriatebalance between ANAMMOX and denitrification communi-ties It was reported that during the ANAMMOX process

2 Journal of Chemistry

Feed

LG M

Figure 1 Start-up pilot

the highest removal efficiency of ammonium and nitrite wasup to 97 and 98 respectively [6]

In comparison to the conventional nitrification-deni-trification process ANAMMOX consumes 100 less biode-gradable organic carbon and at least 50 less oxygen and haslower operating costs [8]

In this work we used ANAMMOX to eliminate thechemical oxygen demand (COD) content Typical range ofCOD concentration in untreated municipal wastewater is250ndash800mgLwhile value of this parameter ismore in super-natant or industrial wastewater than municipal wastewater[9]

The objective of the present study was to optimize CODremoval efficiency with parameters such as ammonium pHand temperature Evaluation of the COD removal and mod-elling the removal efficiency during the ANAMMOX processwere performed using the response surface methodology(RSM) As there are few reports about optimum conditionsfor the elimination of COD in this process we tried to deter-mine the optimum conditions for COD removal through thenovel modelling approach

2 Material and Methods

21 Pilot Study In this study two different pilots have beenused as described below

211 Start-Up Pilot As shown in Figure 1 this pilot was usedto extract ANAMMOX bacteria from activated sludge to beused in the other pilot The start-up pilot was operated inbatch conditions to enrich ANAMMOX biomass This pilotused PVC because the nonpolar molecular structure of PVCdoes not allow it to react against polar water molecules andother soluble materials used in this study Also PVC is asuitable heat barrier and could prevent changes in the reactortemperature which has been proved to be a hindering factorin ANAMMOX bacteria growth The reactor was 15 cm indiameter and 170 cm high yielding an active volume of 30litres to provide plug flow conditions Arbitrary flow inclinedto plug flow when dispersion number 01 prevailed

Figure 2 Growth media used in this study model BC-800

Figure 3 Units of reaction pilot 1mdashfeed tank 2mdashaeration tank(SHARON Single reactor system for High activity AmmoniumRemoval Over Nitrite) 3mdashANAMMOX reactor 4mdashpH adjustmenttanks 5mdasheffluent tank 6mdashPLC system

The suspended growth media used inside the reactor wasmodel BC manufactured by the Abzian Nil Company withspecific surface area of 800m2m3 Figure 2 shows a sample ofthismediaAdiaphragmpumpmade by JesscoGermany noMB 1 40 021 was used to provide circulation in the reactor

212 Reaction Pilot As shown in Figure 3 the reactor usedwas the main combined biological aerobicanaerobic reactorconsisting of the following parts a synthetic 100-litre wastew-ater tank made of poly-Ethylene and an 8 millimetre plasticlevel gage installed on the tank It took between 1 and 3 daysto empty the tank depending on the flow rate In order toavoid microbial growth and possible change in the organicand nutrient concentration of the synthetic wastewater thetank was washed and disinfected weekly using 5 chlorinesolution

Wastewater was transferred to the pilot using adiaphragm pump with a 12 litre per minute capacityand 2 atm Two hand operated flow-meters (between 16 and160mmmin) adjusted the wastewater flow rates The firstpart of the processing of the main pilot comprised two 10

Journal of Chemistry 3

Table 1 The composition of the mineral medium

Trace element mgkgCOD Nutrients for main pilot gL Nutrients for start-up pilot gLAl2(SO4)3 2H2O 19 NH4Cl 1383 NH4Cl 03CaCl2 6H2O 6938 C6H12O6 0156 NaHCO3 007CoCl2 402 KH2PO4 007 NaNO2 015CuCl2 06 NaHCO3 216FeCl3 6H2O 4821MgSO4 7H2O 25635MnSO4 H2O 31(NH4)6Mo7O24 H2O 02NiCl2 6H2O 2ZnCl2 63EDTA 0006

litre transparent Plexiglas aerobic tanks in which suspendedheterotrophic aerobic microorganisms were grown

An aerobic section tank 20 cm wide and long and 25 cmhigh was chosen in order to provide conditions of completemix The above dimensions provided arbitrary conditionsinclined to a complete mix with a dispersion number of over4 Solenoid inlet and outlet valves had diameters of 6 and 8millimetres respectively A manual brass butterfly samplingvalve with a diameter of 38 inches was installed Mixedliquor inside the aerobic reactor was constantly agitated bythe diffused aerator andmixer providing the required oxygenElectric heat elements were installed in each tank Theseelements could manually adjust the heat between 20 and 35degrees centigrade In the first phase of operating the reactorthe wastewater would enter an up-flow sedimentation tankThe diameter of the sedimentation tank was 8 cm and itsgeneral height was 25 cm

The second phase of the process used a 10-litre anaerobicANAMMOX cylinder tank (diameter 10 cm and effectiveheight 100 cm) This tank was filled with fixed media of800m2m3 specific surface area made by the Abzian NilCompany (model BC) The media was first kept in the start-up pilot for 6 months and was covered by ANAMMOXbacteria For sampling four 38 inch brass butterfly valveswere installed on the reactor 25 centimetres apart Like theaerobic tank the heat was adjusted in this reactor usingelectric elements in each tankThe pH (between 7 and 9) wasone of the other main variants studied To adjust the pH inthe tank the following steps were taken in the beginningthe pH was measured by an online measuring device thenthe pHwas measured through a pH transmitter sensor madeby Lutron Taiwan no TR-PHT1A4 and compared with thespecific amount for the tank by using the programmable logiccontrol (PLC) systemmade by Siemens Germany In cases ofdeviation in amounts of up to 02 units one of the solenoidvalves on the aerobic tank that were connected to acid andalkaline solutions would open allowing 3-4 drops of 05solution of either acid or alkaline into the tank After oneminute the above steps were repeated automatically until thepH of the tank reached the desired specific amount for thestudy

Return sludge from awell-operated wastewater treatmentunit in Tehran was used for seeding the reactors Since twoseparate reactors were used in this study start-up and seedingmethods for each are explained individually Initially sludgefrom the wastewater treatment unit was added to the start-up reactor After seeding the system was operated in batchconditions for adaptation and biofilm formation for a periodof 5 months

At the start-up process 40mg-NL ammonium chlorideas the ammonium source and 60mg-NL sodium nitrate asthe nitrate source were used in the inflowThe ratio of nitriteto ammonium was considered to be 15 Sodium bicarbonatewas used with 50mgL as the alkaline source of the reactorIn this study the ratio of bicarbonate to ammonium waschosen to be 12 At this stage to monitor the performanceof the nitrate system nitrite EC pH and alkalinity were theparameters observed

For seeding and start-up of the main reactor aerobicsludge was provided from the wastewater treatment unitThesludge required for the anaerobic section (ANAMMOX) wastaken from the start-up reactor made for this purpose Afterseeding the aerobic reactor the pilot was operated with con-tinuous flow for another month for adaptation of the mixedliquor with the environment enrichment of the microbialpopulation and co-ordination between the qualitative andquantitative sections of the aerobic and anaerobic reactorIn this study the ammonium to nitrite ratio was 15 andammonium to bicarbonate ratio was 12 in the inlet flow ofthe reaction pilot

The constituents of synthetic wastewater which wasprepared on laboratory scales are presented in Table 1 Allreagents provided were of analytical grade from the Merckand Sigma Company Heterotroph and autotroph bacteria inthe reactor were responsible for COD removal and oxidationof the ammonium simultaneously ANAMMOX microor-ganisms in the anaerobic autotroph section need nitrite fortheir growth in addition to ammonium In this reactorpartial oxidation of ammonium (nitritation) occurred in theaerobic section Therefore the inflow only contained CODand ammonium

Throughout the experiments the inflow ammoniumconcentration varied between 40mg-NL and 120mg-NL


Table 2 The natural and coded parameters

Naturalfactors

Codedfactors Unit Low axial

(minus120572 = minus2)Low factorial

(minus1)Centre point

(0)High factorial

(+1)High axial(+120572 = +2)

COD 1199091

mgL 40 975 155 2125 270NH4

+1199092

mg-NL 25 2875 325 3625 40Temp 119909

3

∘C 20 2375 275 3125 35pH 119909

4

mdash 65 705 76 815 87

Table 3 The CCD using the coded factors

Run COD NH4+Inf Temp pH

1 0 0 2 0

2 1 1 minus1 minus1

3 1 1 minus1 1

4 0 0 0 0

5 0 2 0 0

6 minus1 1 minus1 1

7 0 0 0 0

8 minus2 0 0 0

9 minus1 minus1 minus1 minus1

10 0 0 0 0

11 minus1 minus1 1 1

12 1 minus1 minus1 minus1

13 minus1 minus1 minus1 1

14 1 1 1 1

15 0 0 0 0

16 1 1 1 minus1

17 minus1 1 1 minus1

18 0 minus2 0 0

19 minus1 minus1 1 minus1

20 0 0 0 2

21 0 0 0 minus2

22 2 0 0 0

23 1 minus1 1 1

24 minus1 1 minus1 minus1

25 1 minus1 minus1 1

26 1 minus1 1 minus1

27 minus1 1 1 1

28 0 0 0 0

29 0 0 0 0

30 0 0 minus2 0

Ammonia nitrogen and phosphorus were added to theinflow using NH

4CL andNaH

2PO4 Other trace elements for

microbial growth were provided by a stock solution of thetrace element and were 1mL in every 10 litres of the inflow(001 VV) Concentrations of the elements in the traceelement stock solution are explained in Table 1

22 Analytical Techniques SolubleCOD nitrite ammoniumand pH were analysed according to procedures 5220-C4500-NO

2

minus B 4500-NH3C and 4500-H+ B respectively

(American Public Health Association (APHA) 2005) For

Table 4 Design summary for model of COD removal in SBR

Response Name Units Analysis Min Max Mean Model

1198841

CODremoval Polynomial 29 89 6643 Quadratic

measurement of nitrite a Lambda 25 PerkinElmer Inc USAwas usedThe pHmeasurements were performed using a pHmeter model 827 pH lab Metrohm Switzerland

23 Response Surface Methodology (RSM) RSM includes thecollection of the mathematical and statistical methods formodelling and determining themodel equationsThe desiredresponse is a function of several variables RSM is a branchof experimental design and the purpose of its application wasoptimization of the responses of the experiments and numberof tests As a first step we found a suitable approximatefunction between the responses and the set of independentvariables This was a polynomial function of independentvariables The behaviour of the system is explained by thefollowing quadratic equation [10 11]

119910 = 1205730+

119896

sum

119894=1

12057311199091+

119896

sum

119894=1

1205731198941198941199092

119894

+

119896

sum

119894=1

119896

sum

119895=1

120573119894119895119909119894119909119895+ 120598 (2)

where 119910 is the response 1205730 1205731 120573119894119894 120573119894119895are the regression

coefficients 120598 is the error value and 119883119895coded variables of

the systemThe least square method was used to determine the

polynomial approximation Central composite design (CCD)was used to fit this model Table 2 illustrates the CCD for thenatural and coded parameters (as 119909

1 COD 119909

2 ammonium

concentration 1199093 temperature and 119909

4 pH) In the CCD for

each coded factor (Table 2) low axial high axial and factorialand a central point were coded as minus2 minus1 0 +1 and +2respectively The analysis range was from low axial to highaxial and the ranges for 119909

1 1199092 1199093 and 119909

4are considered to

be 40ndash270 25ndash40 20ndash35 and 65ndash87 respectively

3 Results and Discussions

31 Analysis of Variance Using the experimental designmethod 30 runs were considered for modelling and opti-mization of the parameters Table 3 shows the runs of exper-iments with coded factors using the CCD The response ofCOD removal indicated as 119884

1 along with other details is

displayed in Table 4 This table includes the design summary


Table 5 ANOVA for RSM (ANOVA table)

Source Mean square F-value P valueCOD removalmodel 678092 646 00003 Significant

1199091

408204 4281 lt000011199092

8438 088 035931199093

75938 796 001131199094

21004 22 015511199091

1199093

7656 08 038211199091

1199094

9506 1 033131199092

1199094

3306 035 056331199093

1199094

156 0016 089961199092

1

1256 013 072091199092

3

57831 606 002411199092

4

102306 1073 00042Residual 171645Lack of fit 171095 11965 lt00001Pure error 55Cortotal 849737

of COD removal in the SBR reactor According to this tablea quadratic model and polynomial analysis were used forthe final modelling Table 5 shows the analysis of variance(ANOVA) for experimental dataThe ANOVA table providesthe 119875 value 119865-value and mean square for the COD removalmodel and other variances (such as coded factor) and theirinteractions The 119875 value for the model with 95 statisticalprobability (lt00003) is significant Also the statistical valuessuch as lack of fit pure error and Cor total (sum of squarestotal corrected for the mean) are presented Figure 4 showsthe experimental and model data obtained in the design andmodel conditions The design and model data were preparedbased on the experimental and COD removal model in thefollowing equation

CODRemoval = 7544 minus 13041199091 minus 1881199092 minus 5631199093

minus 2961199094minus 219119909

11199093minus 244119909

11199094+ 144119909

21199094

+ 03111990931199094minus 067119909

2

1

minus 4541199092

3

minus 6041199092

4

(3)

In the next step statistical values of the quadratic modelwere determined Table 6 shows 119877-squared adjusted 119877-squared mean CV and so forth Based on statistical val-ues the multiple correlation coefficient Adjusted 119877 squaredpredicted 119877-squared coefficient of variation and the meanremoval efficiency were 081 068 064 147 and 6643respectively

32 Interaction of Main Parameters Figure 5 displays thecontour response surface plot of the interaction betweenthe natural variables for COD removal efficiency Figure 5(a)illustrates the interaction of the reactor temperature andCOD load on COD removal efficiency According to the

y = 09625x + 15071

R2= 09501

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

COD

rem

oval

(mod

el)

COD removal (experiment)

Figure 4 COD removal efficiency computed by the model versusthe experimental COD removal efficiency

Table 6 Statistical values for obtained removal data

R-squared 081Adj R-squared 068Pred R-squared 064Adeqprecision 9883Std Dev 977Mean 6643CV 147PRESSlowast 663889lowastPredicted residual sum of squares of model

plot it is obvious that the higher efficiency occurred inCOD amounts lower than 100mgL and temperature rangesbetween 20 and 35∘C

In this temperature range 26∘C yields the more desirablemodel response Also increasing the COD load is associatedwith higher COD content in the effluent flow Jianlongsuccessfully used an EGSB (Expanded Granular Sludge Bed)reactor to obtain COD removal efficiency of about 844 on500mgL of initial concentrations and 37∘C [12] Molinuevoreported about 51 reduction efficiency acquired during theANAMMOXprocess with 5 gL initial concentration of CODand Hellinga believe that the two groups of bacteria includ-ing ammonium and nitrite oxidation bacteria are sensitiveto environmental temperature and that higher temperatures(35ndash38∘C) facilitate oxidation of ammonium [7 13] AlsoYamamoto successfully demonstrated that nitration occurredwith temperatures in the range of 15ndash30∘C [14]

Table 7 shows the COD elimination percentages in dif-ferent studies in comparison with the results of the presentresearch The effects of pH and COD load in COD removalhave been shown in Figure 5(b) Comparing Figures 5(a) and5(b) reveals that pH and temperature effectiveness in CODremoval follow a similar pattern Therefore according to theresults obtained pH and temperature are themost prominentparameters in COD elimination in ANAMMOX reactors

pH ranges between 7 and 85 provide better conditionsfor the biodegradation of COD COD removal efficiencywas obtained at above 90 in both Figures 5(a) and 5(b)


COD (mgL)

COD removal eff ()

Tem

p (∘

C)

3500

3125

2750

2375

20004000 9750 15550 21250 27000

913001 83854808045

754128726699

687832592699 537124

432654386416

235708

(a)

COD (mgL)27000212501555097504000

pH

650

705

760

815

870COD removal eff ()

235708

386416432654

537124592699

642408687832

726699

754128

80804583854

873652913001

432654

(b)

pH

650

705

760

815

870

40003625325028752500

COD removal eff ()

537124592699

642408

687832

726699746441741165

764061754128770217

782198790674

687832642408

592699537124

NH4 (mgL)

(c)

COD removal eff ()

pH

650

705

760

815

870

Temp (∘C)35003125275023752000

386416432654

537124

592699

687832642408

432654386416

764061770217741165

754128746441

726699

592699

(d)

Figure 5 Contour diagram of natural variables for COD removal efficiency

Table 7 Performed studies of COD removal using the ANAMMOX process

Reactor Type of wastewater COD removal efficiency ReferenceSBR Synthetic 8107 model 766 experimental Present StudySBR Synthetic 826 [15]UASB Piggery manure 51 [6]up-flow fixed-bed Swine wastewater digester liquor 25 plusmn 10 [16]EGSB Brewery wastewater 84 [8]NRBC Synthetic 70 [17]SBR Sanitary landfill leachate 20ndash30 [18]

Egli reported that the role of pH is more important thantemperature in ammonium oxidizing bacteria subgroupssuch as Nitrosomonas and Nitrosomonas europaea and pHcan be used as a controlling tool for operating conditionsThedesirable conditions for these bacteria are pH 75 and 30∘C[19 20]

Figure 5(c) displays the interactions of pH and the influ-ent of ammoniumThe amount of ammonium produced dueto biological consumption is a significant factor in CODbioremoval According to the trend of removal efficiency itcan be found that the COD can be removed if the reactorrsquospH is kept in proper points These points range between


Table 8 The optimum conditions

CODmgL

NH4 inmg-NL

Temp∘C

pHmdash

CODremoval eff

model

CODremoval effexperimental

975 2875 313 772 8107 766

29 89

Re COD

Figure 6 Rams functions and optimal solution

7 and 8 Therefore pH is important in controlling CODremoval in ANAMMOX The final interaction indicates twoimportant parameters the pH and temperature (Figure 5(d))Among the controlling parameters for bacterial and biolog-ical growth pH and temperature are more significant thanthe others Hence desirable rates for these parameters areessential for controlling the ANAMMOX process Regardingthe 119889 plot the most appropriate COD removal conditionsare pH 7-8 and temperatures of 20ndash30∘C Decreasing theCOD loading can be related to the simultaneous growthof ANAMMOX and denitrification communities A studyreported by Jetten demonstrated the highest activity ofANAMMOX bacteria in pH 7ndash85 and a temperature rangeof 30ndash37∘C [21]

A study reported by Yan and Hu demonstrated thatthe maximum COD removal rates were obtained when thetemperature and pH were less than 35∘C and 8 respectively[15] Yamamoto et al reported the highest COD removal ratein a combined SHARONANAMMOX reactor as high as69 in the steady state condition [16] Chen et al reportedthat the optimum pH and temperature for the ANAMMOXpart in the combined CANONANAMMOX reactor were8ndash82 and 35∘C respectively [17] Also Spagni and Marsili-Libelli found that the maximum COD removal with theANAMMOX reactor for sanitary landfill leachate was 35[18]

33 Optimization of COD Removal At this stage optimumconditions for higher elimination of COD were deter-mined An individual desirable function for response (CODremoval) at the optimumconditions is shown in Figure 6Thebold line (in Figure 6) indicates the best solution achieved foroptimization based on the observed higher removal Table 8shows the optimum values with regard to the optimal solu-tion Under optimum conditions COD removal efficiencyof about 8107 was predicted by the model The suggestedparameters were then used under real conditions and theremoval efficiency was equal to 766 It is acceptable for the95 confidence interval

4 Conclusion

With regard to the present study it can be shown that theamounts of COD influent ammonium pH and temperatureare important parameters for biological functions AlsoRSM as a statistical method can be used in the analysis ofexperimental data optimization of considerable factors andmodelling Based on the experimental data and RSM outputthe model of COD removal was determined to be significantwith a 119875 value of 00003 and 1198772 of 081 The optimumconditions with higher removal efficiency (8107) werefound to be COD 975mgL influent ammonium 2875mg-NL pH 772 and temperature 313∘C

Acknowledgment

The authors acknowledge the support of Tehran University ofMedical Sciences and Health Services Grant no 10919 dated17-05-2010

References

[1] A Mulder A A van de Graaf L A Robertson and J GKuenen ldquoAnaerobic ammonium oxidation discovered in adenitrifying fluidized bed reactorrdquo FEMSMicrobiology Ecologyvol 16 no 3 pp 177ndash184 1995

[2] A A van deGraaf P de Bruijn L A RobertsonM SM Jettenand J G Kuenen ldquoMetabolic pathway of anaerobic ammoniumoxidation on the basis of 15N studies in a fluidized bed reactorrdquoMicrobiology vol 143 no 7 pp 2415ndash2421 1997

[3] M Strous E Pelletier S Mangenot et al ldquoDeciphering theevolution and metabolism of an anammox bacterium from acommunity genomerdquo Nature vol 440 no 7085 pp 790ndash7942006

[4] L Zhang P Zheng C-J Tang andR-C Jin ldquoAnaerobic ammo-nium oxidation for treatment of ammonium-rich wastewatersrdquoJournal of Zhejiang University B vol 9 no 5 pp 416ndash426 2008

[5] I Schmidt O Sliekers M Schmid et al ldquoNew concepts ofmicrobial treatment processes for the nitrogen removal inwastewaterrdquo FEMSMicrobiology Reviews vol 27 no 4 pp 481ndash492 2003

[6] Z Yang S Zhou and Y Sun ldquoStart-up of simultaneous removalof ammonium and sulfate from an anaerobic ammonium oxi-dation (anammox) process in an anaerobic up-flow bioreactorrdquoJournal of Hazardous Materials vol 169 no 1-3 pp 113ndash1182009

[7] B Molinuevo M C Garcıa D Karakashev and I AngelidakildquoAnammox for ammonia removal from pig manure effluentseffect of organic matter content on process performancerdquoBioresource Technology vol 100 no 7 pp 2171ndash2175 2009

[8] Y Tal J EMWatts andH J Schreier ldquoAnaerobic ammonium-oxidizing (Anammox) bacteria and associated activity in fixed-film biofilters of a marine recirculating aquaculture systemrdquoApplied and Environmental Microbiology vol 72 no 4 pp2896ndash2904 2006

[9] E Metcalf Wastewater Engineering Treatment and ReuseMcGraw-Hill New York NY USA 2003

[10] Z Zaroual H Chaair A H Essadki K El Ass and M AzzildquoOptimizing the removal of trivalent chromium by electro-coagulation using experimental designrdquo Chemical EngineeringJournal vol 148 no 2-3 pp 488ndash495 2009


[11] T Olmez ldquoThe optimization of Cr(VI) reduction and removalby electrocoagulation using response surface methodologyrdquoJournal of Hazardous Materials vol 162 no 2-3 pp 1371ndash13782009

[12] W Jianlong and K Jing ldquoThe characteristics of anaerobicammonium oxidation (ANAMMOX) by granular sludge froman EGSB reactorrdquo Process Biochemistry vol 40 no 5 pp 1973ndash1978 2005

[13] C Hellinga A A J C Schellen J W Mulder M C Mvan Loosdrecht and J J Heijnen ldquoThe SHARON process aninnovative method for nitrogen removal from ammonium-richwaste waterrdquo Water Science and Technology vol 37 no 9 pp135ndash142 1998

[14] T Yamamoto K Takaki T Koyama and K Furukawa ldquoNovelpartial nitritation treatment for anaerobic digestion liquorof swine wastewater using swim-bed technologyrdquo Journal ofBioscience and Bioengineering vol 102 no 6 pp 497ndash503 2006

[15] J Yan and Y Y Hu ldquoPartial nitrification to nitrite for treatingammonium-rich organic wastewater by immobilized biomasssystemrdquo Bioresource Technology vol 100 no 8 pp 2341ndash23472009

[16] T Yamamoto K Takaki T Koyama and K Furukawa ldquoLong-term stability of partial nitritation of swine wastewater digesterliquor and its subsequent treatment by Anammoxrdquo BioresourceTechnology vol 99 no 14 pp 6419ndash6425 2008

[17] H Chen S Liu F Yang Y Xue and TWang ldquoThe developmentof simultaneous partial nitrification ANAMMOXanddenitrifi-cation (SNAD) process in a single reactor for nitrogen removalrdquoBioresource Technology vol 100 no 4 pp 1548ndash1554 2009

[18] A Spagni and S Marsili-Libelli ldquoNitrogen removal via nitritein a sequencing batch reactor treating sanitary landfill leachaterdquoBioresource Technology vol 100 no 2 pp 609ndash614 2009

[19] A Manipura J R Duncan H J Roman and J E BurgessldquoPotential biological processes available for removal of nitroge-nous compounds from metal industry wastewaterrdquo ProcessSafety and Environmental Protection vol 83 no 5 pp 472ndash4802005

[20] K Egli C Langer H-R Siegrist A J B Zehnder M Wagnerand J R Van der Meer ldquoCommunity analysis of ammonia andnitrite oxidizers during start-up of nitritation reactorsrdquo Appliedand Environmental Microbiology vol 69 no 6 pp 3213ndash32222003

[21] M S M Jetten M Wagner J Fuerst M van LoosdrechtG Kuenen and M Strous ldquoMicrobiology and application ofthe anaerobic ammonium oxidation (ldquoanammoxrdquo) processrdquoCurrent Opinion in Biotechnology vol 12 no 3 pp 283ndash2882001

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Feed

LG M

Figure 1 Start-up pilot

the highest removal efficiency of ammonium and nitrite wasup to 97 and 98 respectively [6]

In comparison to the conventional nitrification-deni-trification process ANAMMOX consumes 100 less biode-gradable organic carbon and at least 50 less oxygen and haslower operating costs [8]

In this work we used ANAMMOX to eliminate thechemical oxygen demand (COD) content Typical range ofCOD concentration in untreated municipal wastewater is250ndash800mgLwhile value of this parameter ismore in super-natant or industrial wastewater than municipal wastewater[9]

The objective of the present study was to optimize CODremoval efficiency with parameters such as ammonium pHand temperature Evaluation of the COD removal and mod-elling the removal efficiency during the ANAMMOX processwere performed using the response surface methodology(RSM) As there are few reports about optimum conditionsfor the elimination of COD in this process we tried to deter-mine the optimum conditions for COD removal through thenovel modelling approach

2 Material and Methods

21 Pilot Study In this study two different pilots have beenused as described below

211 Start-Up Pilot As shown in Figure 1 this pilot was usedto extract ANAMMOX bacteria from activated sludge to beused in the other pilot The start-up pilot was operated inbatch conditions to enrich ANAMMOX biomass This pilotused PVC because the nonpolar molecular structure of PVCdoes not allow it to react against polar water molecules andother soluble materials used in this study Also PVC is asuitable heat barrier and could prevent changes in the reactortemperature which has been proved to be a hindering factorin ANAMMOX bacteria growth The reactor was 15 cm indiameter and 170 cm high yielding an active volume of 30litres to provide plug flow conditions Arbitrary flow inclinedto plug flow when dispersion number 01 prevailed

Figure 2 Growth media used in this study model BC-800

Figure 3 Units of reaction pilot 1mdashfeed tank 2mdashaeration tank(SHARON Single reactor system for High activity AmmoniumRemoval Over Nitrite) 3mdashANAMMOX reactor 4mdashpH adjustmenttanks 5mdasheffluent tank 6mdashPLC system

The suspended growth media used inside the reactor wasmodel BC manufactured by the Abzian Nil Company withspecific surface area of 800m2m3 Figure 2 shows a sample ofthismediaAdiaphragmpumpmade by JesscoGermany noMB 1 40 021 was used to provide circulation in the reactor

212 Reaction Pilot As shown in Figure 3 the reactor usedwas the main combined biological aerobicanaerobic reactorconsisting of the following parts a synthetic 100-litre wastew-ater tank made of poly-Ethylene and an 8 millimetre plasticlevel gage installed on the tank It took between 1 and 3 daysto empty the tank depending on the flow rate In order toavoid microbial growth and possible change in the organicand nutrient concentration of the synthetic wastewater thetank was washed and disinfected weekly using 5 chlorinesolution

Wastewater was transferred to the pilot using adiaphragm pump with a 12 litre per minute capacityand 2 atm Two hand operated flow-meters (between 16 and160mmmin) adjusted the wastewater flow rates The firstpart of the processing of the main pilot comprised two 10














Naturalfactors




(0)High factorial

(+1)High axial(+120572 = +2)

COD 1199091

mgL 40 975 155 2125 270NH4

+1199092

mg-NL 25 2875 325 3625 40Temp 119909

3

∘C 20 2375 275 3125 35pH 119909

4

mdash 65 705 76 815 87



1 0 0 2 0

2 1 1 minus1 minus1

3 1 1 minus1 1

4 0 0 0 0

5 0 2 0 0

6 minus1 1 minus1 1

7 0 0 0 0

8 minus2 0 0 0


10 0 0 0 0




14 1 1 1 1

15 0 0 0 0

16 1 1 1 minus1


18 0 minus2 0 0


20 0 0 0 2

21 0 0 0 minus2

22 2 0 0 0

23 1 minus1 1 1




27 minus1 1 1 1

28 0 0 0 0

29 0 0 0 0

30 0 0 minus2 0


4CL andNaH




2





1198841




119910 = 1205730+

119896

sum

119894=1

12057311199091+

119896

sum

119894=1

1205731198941198941199092

119894

+

119896

sum

119894=1

119896

sum

119895=1

120573119894119895119909119894119909119895+ 120598 (2)





1 COD 119909

2 ammonium




1 1199092 1199093 and 119909

4are considered to









1199091

408204 4281 lt000011199092

8438 088 035931199093

75938 796 001131199094

21004 22 015511199091

1199093

7656 08 038211199091

1199094

9506 1 033131199092

1199094

3306 035 056331199093

1199094

156 0016 089961199092

1

1256 013 072091199092

3

57831 606 002411199092

4




minus 2961199094minus 219119909

11199093minus 244119909

11199094+ 144119909

21199094

+ 03111990931199094minus 067119909

2

1

minus 4541199092

3

minus 6041199092

4

(3)



y = 09625x + 15071

R2= 09501

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

COD

rem

oval

(mod

el)










COD (mgL)

COD removal eff ()

Tem

p (∘

C)

3500

3125

2750

2375

20004000 9750 15550 21250 27000

913001 83854808045

754128726699

687832592699 537124

432654386416

235708

(a)

COD (mgL)27000212501555097504000

pH

650

705

760

815


235708

386416432654

537124592699

642408687832

726699

754128

80804583854

873652913001

432654

(b)

pH

650

705

760

815

870

40003625325028752500

COD removal eff ()

537124592699

642408

687832

726699746441741165

764061754128770217

782198790674

687832642408

592699537124

NH4 (mgL)

(c)

COD removal eff ()

pH

650

705

760

815

870

Temp (∘C)35003125275023752000

386416432654

537124

592699

687832642408

432654386416

764061770217741165

754128746441

726699

592699

(d)








CODmgL

NH4 inmg-NL

Temp∘C

pHmdash

CODremoval eff

model


975 2875 313 772 8107 766

29 89

Re COD





4 Conclusion


Acknowledgment


References
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of














Naturalfactors




(0)High factorial

(+1)High axial(+120572 = +2)

COD 1199091

mgL 40 975 155 2125 270NH4

+1199092

mg-NL 25 2875 325 3625 40Temp 119909

3

∘C 20 2375 275 3125 35pH 119909

4

mdash 65 705 76 815 87



1 0 0 2 0

2 1 1 minus1 minus1

3 1 1 minus1 1

4 0 0 0 0

5 0 2 0 0

6 minus1 1 minus1 1

7 0 0 0 0

8 minus2 0 0 0


10 0 0 0 0




14 1 1 1 1

15 0 0 0 0

16 1 1 1 minus1


18 0 minus2 0 0


20 0 0 0 2

21 0 0 0 minus2

22 2 0 0 0

23 1 minus1 1 1




27 minus1 1 1 1

28 0 0 0 0

29 0 0 0 0

30 0 0 minus2 0


4CL andNaH




2





1198841




119910 = 1205730+

119896

sum

119894=1

12057311199091+

119896

sum

119894=1

1205731198941198941199092

119894

+

119896

sum

119894=1

119896

sum

119895=1

120573119894119895119909119894119909119895+ 120598 (2)





1 COD 119909

2 ammonium




1 1199092 1199093 and 119909

4are considered to









1199091

408204 4281 lt000011199092

8438 088 035931199093

75938 796 001131199094

21004 22 015511199091

1199093

7656 08 038211199091

1199094

9506 1 033131199092

1199094

3306 035 056331199093

1199094

156 0016 089961199092

1

1256 013 072091199092

3

57831 606 002411199092

4




minus 2961199094minus 219119909

11199093minus 244119909

11199094+ 144119909

21199094

+ 03111990931199094minus 067119909

2

1

minus 4541199092

3

minus 6041199092

4

(3)



y = 09625x + 15071

R2= 09501

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

COD

rem

oval

(mod

el)










COD (mgL)

COD removal eff ()

Tem

p (∘

C)

3500

3125

2750

2375

20004000 9750 15550 21250 27000

913001 83854808045

754128726699

687832592699 537124

432654386416

235708

(a)

COD (mgL)27000212501555097504000

pH

650

705

760

815


235708

386416432654

537124592699

642408687832

726699

754128

80804583854

873652913001

432654

(b)

pH

650

705

760

815

870

40003625325028752500

COD removal eff ()

537124592699

642408

687832

726699746441741165

764061754128770217

782198790674

687832642408

592699537124

NH4 (mgL)

(c)

COD removal eff ()

pH

650

705

760

815

870

Temp (∘C)35003125275023752000

386416432654

537124

592699

687832642408

432654386416

764061770217741165

754128746441

726699

592699

(d)








CODmgL

NH4 inmg-NL

Temp∘C

pHmdash

CODremoval eff

model


975 2875 313 772 8107 766

29 89

Re COD





4 Conclusion


Acknowledgment


References
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




1199091

408204 4281 lt000011199092

8438 088 035931199093

75938 796 001131199094

21004 22 015511199091

1199093

7656 08 038211199091

1199094

9506 1 033131199092

1199094

3306 035 056331199093

1199094

156 0016 089961199092

1

1256 013 072091199092

3

57831 606 002411199092

4




minus 2961199094minus 219119909

11199093minus 244119909

11199094+ 144119909

21199094

+ 03111990931199094minus 067119909

2

1

minus 4541199092

3

minus 6041199092

4

(3)



y = 09625x + 15071

R2= 09501

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

COD

rem

oval

(mod

el)










COD (mgL)

COD removal eff ()

Tem

p (∘

C)

3500

3125

2750

2375

20004000 9750 15550 21250 27000

913001 83854808045

754128726699

687832592699 537124

432654386416

235708

(a)

COD (mgL)27000212501555097504000

pH

650

705

760

815


235708

386416432654

537124592699

642408687832

726699

754128

80804583854

873652913001

432654

(b)

pH

650

705

760

815

870

40003625325028752500

COD removal eff ()

537124592699

642408

687832

726699746441741165

764061754128770217

782198790674

687832642408

592699537124

NH4 (mgL)

(c)

COD removal eff ()

pH

650

705

760

815

870

Temp (∘C)35003125275023752000

386416432654

537124

592699

687832642408

432654386416

764061770217741165

754128746441

726699

592699

(d)








CODmgL

NH4 inmg-NL

Temp∘C

pHmdash

CODremoval eff

model


975 2875 313 772 8107 766

29 89

Re COD





4 Conclusion


Acknowledgment


References
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


COD (mgL)

COD removal eff ()

Tem

p (∘

C)

3500

3125

2750

2375

20004000 9750 15550 21250 27000

913001 83854808045

754128726699

687832592699 537124

432654386416

235708

(a)

COD (mgL)27000212501555097504000

pH

650

705

760

815


235708

386416432654

537124592699

642408687832

726699

754128

80804583854

873652913001

432654

(b)

pH

650

705

760

815

870

40003625325028752500

COD removal eff ()

537124592699

642408

687832

726699746441741165

764061754128770217

782198790674

687832642408

592699537124

NH4 (mgL)

(c)

COD removal eff ()

pH

650

705

760

815

870

Temp (∘C)35003125275023752000

386416432654

537124

592699

687832642408

432654386416

764061770217741165

754128746441

726699

592699

(d)








CODmgL

NH4 inmg-NL

Temp∘C

pHmdash

CODremoval eff

model


975 2875 313 772 8107 766

29 89

Re COD





4 Conclusion


Acknowledgment


References
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



CODmgL

NH4 inmg-NL

Temp∘C

pHmdash

CODremoval eff

model


975 2875 313 772 8107 766

29 89

Re COD





4 Conclusion


Acknowledgment


References
































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Research Article Optimization and Modelling of Chemical ...

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