Acute and chronic toxicity of nickel to nitrifiers at different temperatures
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摘要
This study investigated the acute nickel toxicity on nitrification of low ammonia synthetic wastewater at 10, 23, and 35°C. The nickel inhibition half-velocity constants(K_(I,Ni)) for ammonia oxidizing bacteria(AOB) and nitrite oxidizing bacteria(NOB) based on Ni/MLSS ratio at 10, 23, and 35°C were 5.4 and 5.6 mg Ni/g MLSS, 4.6 and 3.5 mg Ni/g MLSS, and 9.1 and 2.7 mg Ni/g MLSS, respectively. In addition, chronic toxicity of nickel to nitrification of low ammonia synthetic wastewater was investigated at 10°C in two sequencing batch reactors(SBRs). Long-term SBRs operation and short-term batch tests were comparable with respect to the extent of inhibition and corresponding Ni/MLSS ratio. The μ_(max), b, and K_o of AOB were 0.16 day~(-1), 0.098 day~(-1) and 2.08 mg O_2/L after long-term acclimatization to nickel of 1 mg/L at 10°C, high dissolved oxygen(DO)(7 mg/L) and long solids retention time(SRT) of 63–70 days. Acute nickel toxicity of nitrifying bacteria was completely reversible.
This study investigated the acute nickel toxicity on nitrification of low ammonia synthetic wastewater at 10, 23, and 35°C. The nickel inhibition half-velocity constants(K_(I,Ni)) for ammonia oxidizing bacteria(AOB) and nitrite oxidizing bacteria(NOB) based on Ni/MLSS ratio at 10, 23, and 35°C were 5.4 and 5.6 mg Ni/g MLSS, 4.6 and 3.5 mg Ni/g MLSS, and 9.1 and 2.7 mg Ni/g MLSS, respectively. In addition, chronic toxicity of nickel to nitrification of low ammonia synthetic wastewater was investigated at 10°C in two sequencing batch reactors(SBRs). Long-term SBRs operation and short-term batch tests were comparable with respect to the extent of inhibition and corresponding Ni/MLSS ratio. The μ_(max), b, and K_o of AOB were 0.16 day~(-1), 0.098 day~(-1) and 2.08 mg O_2/L after long-term acclimatization to nickel of 1 mg/L at 10°C, high dissolved oxygen(DO)(7 mg/L) and long solids retention time(SRT) of 63–70 days. Acute nickel toxicity of nitrifying bacteria was completely reversible.
This study investigated the acute nickel toxicity on nitrification of low ammonia synthetic wastewater at 10, 23, and 35°C. The nickel inhibition half-velocity constants(K_(I,Ni)) for ammonia oxidizing bacteria(AOB) and nitrite oxidizing bacteria(NOB) based on Ni/MLSS ratio at 10, 23, and 35°C were 5.4 and 5.6 mg Ni/g MLSS, 4.6 and 3.5 mg Ni/g MLSS, and 9.1 and 2.7 mg Ni/g MLSS, respectively. In addition, chronic toxicity of nickel to nitrification of low ammonia synthetic wastewater was investigated at 10°C in two sequencing batch reactors(SBRs). Long-term SBRs operation and short-term batch tests were comparable with respect to the extent of inhibition and corresponding Ni/MLSS ratio. The μ_(max), b, and K_o of AOB were 0.16 day~(-1), 0.098 day~(-1) and 2.08 mg O_2/L after long-term acclimatization to nickel of 1 mg/L at 10°C, high dissolved oxygen(DO)(7 mg/L) and long solids retention time(SRT) of 63–70 days. Acute nickel toxicity of nitrifying bacteria was completely reversible.
引文
Akhtar,M.F.,Ashraf,M.,Javeed,A.,Anjum,A.A.,Sharif,A.,Saleem,M.,et al.,2018.Association of textile industry effluent with mutagenicity and its toxic health implications upon acute and sub-chronic exposure.Environ.Monit.Assess.190,179.
Anthonisen,A.C.,Loehr,R.C.,Prakasam,T.B.S.,Srinath,E.G.,1976.Inhibition of nitrification by ammonia and nitrous acid.J.Water Pollut.Control Fed.835-852.
APHA,2005.Standard Methods for the Examination of Water&Wastewater.American Public Health Association/American Water Works Association/Water Environment Federation,Washington DC.
Aslan,S.,Sozudogru,O.,2017.Individual and combined effects of nickel and copper on nitrification organisms.Ecol.Eng.99,126-133.
Bae,W.,Baek,S.,Chung,J.,Lee,Y.,2001.Optimal operational factors for nitrite accumulation in batch reactors.Biodegradation.12,359-366.
Blum,D.J.W.,Speece,R.,1991.A database of chemical toxicity to environmental bacteria and its use in interspecies comparisons and correlations.J.Water Pollut.Control Fed.63,198-207.
Buch,A.C.,Niemeyer,J.C.,Correia,M.E.F.,Silva-Filho,E.V.,2016.Ecotoxicity of mercury to Folsomia candida and Proisotoma minuta(Collembola:Isotomidae)in tropical soils:baseline for ecological risk assessment.Ecotoxicol.Environ.Saf.127,22-29.
Carletti,G.,Fatone,F.,Bolzonella,D.,Cecchi,F.,Carletti,G.,2008.Occurrence and fate of heavy metals in large wastewater treatment plants treating municipal and industrial wastewaters.Water Sci.Technol.57,1329-1336.
?e?en,F.,Semerci,N.,Geyik,A.G.,2010.Inhibitory effects of Cu,Zn,Ni and Co on nitrification and relevance of speciation.J.Chem.Technol.Biotechnol.85,520-528.
Cheng,L.,Li,X.,Jiang,R.,Wang,C.,Yin,H.B.,2011.Effects of Cr(VI)on the performance and kinetics of the activated sludge process.Bioresour.Technol.102,797-804.
Chipasa,K.B.,2003.Accumulation and fate of selected heavy metals in a biological wastewater treatment system.Waste Manag.23,135-143.
Communities,E.,2001.Pollutants in urban wastewater and sewage sludge.Office for Official Publications of the European Communities,Luxembourg.
Dilek,F.B.,G?k?ay,C.F.,1996.Microbiology of activated sludge treating wastewater containing Ni(II)and Cr(VI).Water Sci.Technol.34,183-191.
Gadd,G.M.,Griffiths,A.J.,1977.Microorganisms and heavy metal toxicity.Microb.Ecol.4,303-317.
Ge,S.,Wang,S.,Yang,X.,Qiu,S.,Li,B.,Peng,Y.,2015.Detection of nitrifiers and evaluation of partial nitrification for wastewater treatment:a review.Chemosphere.140,85-98.
Gikas,P.,2008.Single and combined effects of nickel(Ni(II))and cobalt(Co(II))ions on activated sludge and on other aerobic microorganisms:a review.J.Hazard.Mater.159,187-203.
Gustafsson,J.P.,2013.Visual MINTEQ Version 3.1.Department of Sustainable Development.Environmental Science and Engineering,KTH,Stockholm.
Hellinga,C.,Schellen,A.,Mulder,J.W.,van Loosdrecht,M.,Heijnen,J.J.,1998.The SHARON process:an innovative method for nitrogen removal from ammonium-rich waste water.Water Sci.Technol.37,135-142.
Hernandez-Martinez,G.R.,Ortiz-Alvarez,D.,Perez-Roa,M.,Urbina-Suarez,N.A.,Thalasso,F.,2018.Multiparameter analysis of activated sludge inhibition by nickel,cadmium,and cobalt.J.Hazard.Mater.351,63-70.
Hu,Z.,Chandran,K.,Grasso,D.,Smets,B.F.,2003.Impact of metal sorption and internalization on nitrification inhibition.Environ.Sci.Technol.37,728-734.
Hu,Z.,Chandran,K.,Grasso,D.,Smets,B.F.,2004.Comparison of nitrification inhibition by metals in batch and continuous flow reactors.Water Res.38,3949-3959.
Insel,G.,Karahan,O.,Ozdemir,S.,Pala,L.,Katipoglu,T.,Cokgor,E.U.,et al.,2006.Unified basis for the respirometric evaluation of inhibition for activated sludge.J.Environ.Sci.Health A Tox.Hazard.Subst.Environ.Eng.41,1763-1780.
Kapoor,V.,Li,X.,Elk,M.,Chandran,K.,Impellitteri,C.A.,Santo Domingo,J.W.,2015.Impact of heavy metals on transcriptional and physiological activity of nitrifying bacteria.Environ.Sci.Technol.49,13454-13462.
Karvelas,M.,Katsoyiannis,A.,Samara,C.,2003.Occurrence and fate of heavy metals in the wastewater treatment process.Chemosphere.53,1201-1210.
Keithly,J.,Brooker,J.A.,Deforest,D.K.,Wu,B.K.,Brix,K.V.,2004.Acute and chronic toxicity of nickel to a cladoceran(Ceriodaphnia dubia)and an amphipod(Hyalella azteca).Environ.Toxicol.Chem.23,691-696.
Leonard,E.M.,Barcarolli,I.,Silva,K.R.,Wasielesky,W.,Wood,C.M.,Bianchini,A.J.,et al.,2011.The effects of salinity on acute and chronic nickel toxicity and bioaccumulation in two euryhaline crustaceans:Litopenaeus vannamei and Excirolana armata.Comp.Biochem.Physiol.C Toxicol.Pharmacol.154,409-419.
Lewandowski,Z.,1987.Behaviour of biological reactors in the presence of toxic compounds.Water Res.21,147-153.
Li,X.,Kapoor,V.,Impelliteri,C.,Chandran,K.,Domingo,J.W.S.,2016.Measuring nitrification inhibition by metals in wastewater treatment systems:current state of science and fundamental research needs.Crit.Rev.Environ.Sci.Technol.46,249-289.
Liu,G.,Wang,J.,2014.Role of solids retention time on complete nitrification:mechanistic understanding and modeling.J.Environ.Eng-ASCE.140,48-56.
Liu,X.,Kim,M.,Nakhla,G.,2017a.Operational conditions for successful partial nitrification in a sequencing batch reactor(SBR)based on process kinetics.Environ.Technol.38,694-704.
Liu,X.,Kim,M.,Nakhla,G.,2017b.A model for determination of operational conditions for successful shortcut nitrification.Environ.Sci.Pollut.R.24,3539-3549.
Liu,X.,Kim,M.,Nakhla,G.,2018.Performance and kinetics of nitrification of low ammonia wastewater at low temperature.Water Environ.Res.90,498-509.
Mauret,M.,Paul,E.,Puech-Costes,E.,Maurette,M.,Baptiste,P.,1996.Application of experimental research methodology to the study of nitrification in mixed culture.Water Sci.Technol.34,245-252.
Metcalf,Eddy,2013.Wastewater Engineering:Treatment and Reuse.McGraw-Hill Education.
Neufeld,R.,Greenfield,J.,Rieder,B.,1986.Temperature,cyanide and phenolic nitrification inhibition.Water Res.20,633-642.
Nies,D.H.,1999.Microbial heavy metal resistance.Appl.Microbiol.Biotechnol.51,730-750.
Pereira,C.M.,Deruytter,D.,Blust,R.,De Schamphelaere,K.A.C.,2017.Effect of temperature on chronic toxicity of copper,zinc,and nickel to Daphnia magna.Environ.Toxicol.Chem.36,1909-1916.
Randall,C.,Buth,D.,1984.Nitrite build-up in activated sludge resulting from combined temperature and toxicity effects.J.Water Pollut.Control Fed.56,1045-1049.
Sato,C.,Schnoor,J.L.,McDonald,D.B.,1986.Effects of copper and nickel on the growth of Nitrosomonas europaea.Environ.Toxicol.Water Qual.1,357-376.
Semerci,N.,?e?en,F.,2007.Importance of cadmium speciation in nitrification inhibition.J.Hazard.Mater.147,503-512.
Soliman,M.,Eldyasti,A.,2018.Ammonia-oxidizing bacteria(AOB):opportunities and applications-a review.Rev.Environ.Sci.Biotechnol.17,285-321.
Stasinakis,A.S.,Mamais,D.,Thomaidis,N.S.,Lekkas,T.D.,2002.Effect of chromium(VI)on bacterial kinetics of heterotrophic biomass of activated sludge.Water Res.36,3341-3349.
Sujarittanonta,S.,Sherrard,J.H.,1981.Activated sludge nickel toxicity studies.J.Water Pollut.Control Fed.53,1314-1322.
Sun,J.,Yang,Q.,Wang,D.,Wang,S.,Chen,F.,Zhong,Y.,et al.,2017.Nickel toxicity to the performance and microbial community of enhanced biological phosphorus removal system.Chem.Eng.J.313,415-423.
Teijon,G.,Candela,L.,Tamoh,K.,Molina-Díaz,A.,FernándezAlba,A.R.,2010.Occurrence of emerging contaminants,priority substances(2008/105/CE)and heavy metals in treated wastewater and groundwater at Depurbaix facility(Barcelona,Spain).Sci.Total Environ.408,3584-3595.
Wong-Chong,G.,Loehr,R.,1975.The kinetics of microbial nitrification.Water Res.9,1099-1106.
Yang,Q.,Sun,J.,Wang,D.,Wang,S.,Chen,F.,Yao,F.,et al.,2017.Effect of nickel on the flocculability,settleability,and dewaterability of activated sludge.Bioresour.Technol.224,188-196.
Yeung,C.H.,Francis,C.A.,Criddle,C.S.,2013.Adaptation of nitrifying microbial biomass to nickel in batch incubations.Appl.Microbiol.Biotechnol.97,847-857.
Yin,K.,Lv,M.,Wang,Q.,Wu,Y.,Liao,C.,Zhang,W.,et al.,2016.Simultaneous bioremediation and biodetection of mercury ion through surface display of carboxylesterase E2 from Pseudomonas aeruginosa PA1.Water Res.103,383-390.
You,S.J.,Tsai,Y.P.,Huang,R.Y.,2009.Effect of heavy metals on nitrification performance in different activated sludge processes.J.Hazard.Mater.165,987-994.
Yuan,L.,Zhi,W.,Liu,Y.,Karyala,S.,Vikesland,P.,Chen,X.,et al.,2014.Lead toxicity to the performance,viability,and community composition of activated sludge microorganisms.Environ.Sci.Technol.49,824-830.
Zhu,G.,Peng,Y.,Li,B.,Guo,J.,Yang,Q.,Wang,S.,2008.Biological Removal of Nitrogen from Wastewater,Rev.Environ.Contam.Toxicol.Springer,New York,pp.159-195.
Anthonisen,A.C.,Loehr,R.C.,Prakasam,T.B.S.,Srinath,E.G.,1976.Inhibition of nitrification by ammonia and nitrous acid.J.Water Pollut.Control Fed.835-852.
APHA,2005.Standard Methods for the Examination of Water&Wastewater.American Public Health Association/American Water Works Association/Water Environment Federation,Washington DC.
Aslan,S.,Sozudogru,O.,2017.Individual and combined effects of nickel and copper on nitrification organisms.Ecol.Eng.99,126-133.
Bae,W.,Baek,S.,Chung,J.,Lee,Y.,2001.Optimal operational factors for nitrite accumulation in batch reactors.Biodegradation.12,359-366.
Blum,D.J.W.,Speece,R.,1991.A database of chemical toxicity to environmental bacteria and its use in interspecies comparisons and correlations.J.Water Pollut.Control Fed.63,198-207.
Buch,A.C.,Niemeyer,J.C.,Correia,M.E.F.,Silva-Filho,E.V.,2016.Ecotoxicity of mercury to Folsomia candida and Proisotoma minuta(Collembola:Isotomidae)in tropical soils:baseline for ecological risk assessment.Ecotoxicol.Environ.Saf.127,22-29.
Carletti,G.,Fatone,F.,Bolzonella,D.,Cecchi,F.,Carletti,G.,2008.Occurrence and fate of heavy metals in large wastewater treatment plants treating municipal and industrial wastewaters.Water Sci.Technol.57,1329-1336.
?e?en,F.,Semerci,N.,Geyik,A.G.,2010.Inhibitory effects of Cu,Zn,Ni and Co on nitrification and relevance of speciation.J.Chem.Technol.Biotechnol.85,520-528.
Cheng,L.,Li,X.,Jiang,R.,Wang,C.,Yin,H.B.,2011.Effects of Cr(VI)on the performance and kinetics of the activated sludge process.Bioresour.Technol.102,797-804.
Chipasa,K.B.,2003.Accumulation and fate of selected heavy metals in a biological wastewater treatment system.Waste Manag.23,135-143.
Communities,E.,2001.Pollutants in urban wastewater and sewage sludge.Office for Official Publications of the European Communities,Luxembourg.
Dilek,F.B.,G?k?ay,C.F.,1996.Microbiology of activated sludge treating wastewater containing Ni(II)and Cr(VI).Water Sci.Technol.34,183-191.
Gadd,G.M.,Griffiths,A.J.,1977.Microorganisms and heavy metal toxicity.Microb.Ecol.4,303-317.
Ge,S.,Wang,S.,Yang,X.,Qiu,S.,Li,B.,Peng,Y.,2015.Detection of nitrifiers and evaluation of partial nitrification for wastewater treatment:a review.Chemosphere.140,85-98.
Gikas,P.,2008.Single and combined effects of nickel(Ni(II))and cobalt(Co(II))ions on activated sludge and on other aerobic microorganisms:a review.J.Hazard.Mater.159,187-203.
Gustafsson,J.P.,2013.Visual MINTEQ Version 3.1.Department of Sustainable Development.Environmental Science and Engineering,KTH,Stockholm.
Hellinga,C.,Schellen,A.,Mulder,J.W.,van Loosdrecht,M.,Heijnen,J.J.,1998.The SHARON process:an innovative method for nitrogen removal from ammonium-rich waste water.Water Sci.Technol.37,135-142.
Hernandez-Martinez,G.R.,Ortiz-Alvarez,D.,Perez-Roa,M.,Urbina-Suarez,N.A.,Thalasso,F.,2018.Multiparameter analysis of activated sludge inhibition by nickel,cadmium,and cobalt.J.Hazard.Mater.351,63-70.
Hu,Z.,Chandran,K.,Grasso,D.,Smets,B.F.,2003.Impact of metal sorption and internalization on nitrification inhibition.Environ.Sci.Technol.37,728-734.
Hu,Z.,Chandran,K.,Grasso,D.,Smets,B.F.,2004.Comparison of nitrification inhibition by metals in batch and continuous flow reactors.Water Res.38,3949-3959.
Insel,G.,Karahan,O.,Ozdemir,S.,Pala,L.,Katipoglu,T.,Cokgor,E.U.,et al.,2006.Unified basis for the respirometric evaluation of inhibition for activated sludge.J.Environ.Sci.Health A Tox.Hazard.Subst.Environ.Eng.41,1763-1780.
Kapoor,V.,Li,X.,Elk,M.,Chandran,K.,Impellitteri,C.A.,Santo Domingo,J.W.,2015.Impact of heavy metals on transcriptional and physiological activity of nitrifying bacteria.Environ.Sci.Technol.49,13454-13462.
Karvelas,M.,Katsoyiannis,A.,Samara,C.,2003.Occurrence and fate of heavy metals in the wastewater treatment process.Chemosphere.53,1201-1210.
Keithly,J.,Brooker,J.A.,Deforest,D.K.,Wu,B.K.,Brix,K.V.,2004.Acute and chronic toxicity of nickel to a cladoceran(Ceriodaphnia dubia)and an amphipod(Hyalella azteca).Environ.Toxicol.Chem.23,691-696.
Leonard,E.M.,Barcarolli,I.,Silva,K.R.,Wasielesky,W.,Wood,C.M.,Bianchini,A.J.,et al.,2011.The effects of salinity on acute and chronic nickel toxicity and bioaccumulation in two euryhaline crustaceans:Litopenaeus vannamei and Excirolana armata.Comp.Biochem.Physiol.C Toxicol.Pharmacol.154,409-419.
Lewandowski,Z.,1987.Behaviour of biological reactors in the presence of toxic compounds.Water Res.21,147-153.
Li,X.,Kapoor,V.,Impelliteri,C.,Chandran,K.,Domingo,J.W.S.,2016.Measuring nitrification inhibition by metals in wastewater treatment systems:current state of science and fundamental research needs.Crit.Rev.Environ.Sci.Technol.46,249-289.
Liu,G.,Wang,J.,2014.Role of solids retention time on complete nitrification:mechanistic understanding and modeling.J.Environ.Eng-ASCE.140,48-56.
Liu,X.,Kim,M.,Nakhla,G.,2017a.Operational conditions for successful partial nitrification in a sequencing batch reactor(SBR)based on process kinetics.Environ.Technol.38,694-704.
Liu,X.,Kim,M.,Nakhla,G.,2017b.A model for determination of operational conditions for successful shortcut nitrification.Environ.Sci.Pollut.R.24,3539-3549.
Liu,X.,Kim,M.,Nakhla,G.,2018.Performance and kinetics of nitrification of low ammonia wastewater at low temperature.Water Environ.Res.90,498-509.
Mauret,M.,Paul,E.,Puech-Costes,E.,Maurette,M.,Baptiste,P.,1996.Application of experimental research methodology to the study of nitrification in mixed culture.Water Sci.Technol.34,245-252.
Metcalf,Eddy,2013.Wastewater Engineering:Treatment and Reuse.McGraw-Hill Education.
Neufeld,R.,Greenfield,J.,Rieder,B.,1986.Temperature,cyanide and phenolic nitrification inhibition.Water Res.20,633-642.
Nies,D.H.,1999.Microbial heavy metal resistance.Appl.Microbiol.Biotechnol.51,730-750.
Pereira,C.M.,Deruytter,D.,Blust,R.,De Schamphelaere,K.A.C.,2017.Effect of temperature on chronic toxicity of copper,zinc,and nickel to Daphnia magna.Environ.Toxicol.Chem.36,1909-1916.
Randall,C.,Buth,D.,1984.Nitrite build-up in activated sludge resulting from combined temperature and toxicity effects.J.Water Pollut.Control Fed.56,1045-1049.
Sato,C.,Schnoor,J.L.,McDonald,D.B.,1986.Effects of copper and nickel on the growth of Nitrosomonas europaea.Environ.Toxicol.Water Qual.1,357-376.
Semerci,N.,?e?en,F.,2007.Importance of cadmium speciation in nitrification inhibition.J.Hazard.Mater.147,503-512.
Soliman,M.,Eldyasti,A.,2018.Ammonia-oxidizing bacteria(AOB):opportunities and applications-a review.Rev.Environ.Sci.Biotechnol.17,285-321.
Stasinakis,A.S.,Mamais,D.,Thomaidis,N.S.,Lekkas,T.D.,2002.Effect of chromium(VI)on bacterial kinetics of heterotrophic biomass of activated sludge.Water Res.36,3341-3349.
Sujarittanonta,S.,Sherrard,J.H.,1981.Activated sludge nickel toxicity studies.J.Water Pollut.Control Fed.53,1314-1322.
Sun,J.,Yang,Q.,Wang,D.,Wang,S.,Chen,F.,Zhong,Y.,et al.,2017.Nickel toxicity to the performance and microbial community of enhanced biological phosphorus removal system.Chem.Eng.J.313,415-423.
Teijon,G.,Candela,L.,Tamoh,K.,Molina-Díaz,A.,FernándezAlba,A.R.,2010.Occurrence of emerging contaminants,priority substances(2008/105/CE)and heavy metals in treated wastewater and groundwater at Depurbaix facility(Barcelona,Spain).Sci.Total Environ.408,3584-3595.
Wong-Chong,G.,Loehr,R.,1975.The kinetics of microbial nitrification.Water Res.9,1099-1106.
Yang,Q.,Sun,J.,Wang,D.,Wang,S.,Chen,F.,Yao,F.,et al.,2017.Effect of nickel on the flocculability,settleability,and dewaterability of activated sludge.Bioresour.Technol.224,188-196.
Yeung,C.H.,Francis,C.A.,Criddle,C.S.,2013.Adaptation of nitrifying microbial biomass to nickel in batch incubations.Appl.Microbiol.Biotechnol.97,847-857.
Yin,K.,Lv,M.,Wang,Q.,Wu,Y.,Liao,C.,Zhang,W.,et al.,2016.Simultaneous bioremediation and biodetection of mercury ion through surface display of carboxylesterase E2 from Pseudomonas aeruginosa PA1.Water Res.103,383-390.
You,S.J.,Tsai,Y.P.,Huang,R.Y.,2009.Effect of heavy metals on nitrification performance in different activated sludge processes.J.Hazard.Mater.165,987-994.
Yuan,L.,Zhi,W.,Liu,Y.,Karyala,S.,Vikesland,P.,Chen,X.,et al.,2014.Lead toxicity to the performance,viability,and community composition of activated sludge microorganisms.Environ.Sci.Technol.49,824-830.
Zhu,G.,Peng,Y.,Li,B.,Guo,J.,Yang,Q.,Wang,S.,2008.Biological Removal of Nitrogen from Wastewater,Rev.Environ.Contam.Toxicol.Springer,New York,pp.159-195.