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Control strategy of shortcut nitrification

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Journal of Environmental Sciences 2006年第1期18卷 58-61页

作者： qaisar mahmood Department of Environmental Engineering Zhejiang University Hangzhou 310029 China.

Shortcut nitrification for ammonium-rich wastewater is energy-saving and cost-effective procedure that has become one of the hotspots in the field of biological denitrogenation. An orthogonal experiment was performed to study the combined effects of operational parameters on the performance of internal-loop airlift bioreactor for shortcut nitrification. The optimum operational parameters for the shortcut nitrification were fotmd as temperature 35 ℃, pH 8.0, dissolved oxygen concentration 1.0 mg/L, ammonium concentration 4 mmol/L and HRT 16 h, which have different influence on the performance of shortcut nitrification reactor. The pH, temperature and dissolved oxygen concentration have significant bearing on the process. The results showed that the shortcut nitrification reactor could be successfully started up within 42 d, and the reactor performance is steady with minimum NO2-/NOx- of 85.2%, maximum 93.4% and average value of 91.4% in effluent. Based on the analysis of experimental data, a new control strategy named “priority ＋ combination” for shortcut nitrification was suggested. Through this strategy, the startup and operation of shortcut nitrification for ammonium-rich sludge digester liquids were optimized. The control strategy works well to keep the reactor operation in steady state and in achieving high-efficiency for shortcut nitrification.

关键词： internal-loop airlift bioreactor shortcut nitrification orthogonal experiment control strategy sludge digester liquids

Activated sludge-mediated biodegradation of dimethyl phthalate under fermentative conditions

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Journal of Environmental Sciences 2008年第8期20卷 922-926页

作者： mahmood qaisar Department of Botany Federal Government Post Graduate College Sector H-8 IslamabadPakistan

The biodegradation of dimethyl phthalate(DMP)was investigated under fermentative conditions in this *** nature of the intermediate compounds and the extent of mineralization were probed using high-pressure liquid chromatography(HPLC)and liquid chromatography-mass spectrometry(LC-MS)*** fermentative bacteria were able to biodegrade the DMP under anaerobic conditions,with the biodegradation rate of 0.36 mg DMP/(L·h).The results demonstrated that the DMP degradation under fermentative conditions ...

关键词： activated sludge biodegradation dimethyl phthalate fermentation phthalic acid mineralization

Effects of loading rate and hydraulic residence time on anoxic sulfide biooxidation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第7期8卷 1149-1156页

作者： mahmood qaisar ISLAM Ejazul Department of Environmental Engineering Zhejiang University

The optimal operation conditions in an anoxic sulfide oxidizing (ASO) bioreactor were investigated. The maximal removal rates for sulfide and nitrate were found to be 4.18 kg/(m3·d) and 1.73 kg/(m3·d), respectively. The volumetrical volumetric loading rates (LRs) observed through decreasing hydraulic retention time (HRT) at fixed substrate concentration are higher than those by increasing substrate concentration at fixed HRT. The sulfide oxidation in ASO reactor was partially producing both sulfate and sulfur; but the amount of sulfate produced was approximately one third that of sulfur. The process was able to tolerate high sulfide concentration, as the sulfide removal percentage always remained near 99% when influent concentration was up to 580 mg/L. It tolerated relatively lower nitrate concentration because the removal percentage dropped to 85% when influent con- centration was increased above 110 mg/L. The process can tolerate shorter HRT but careful operation is needed. Nitrate conversion was more sensitive to HRT than sulfide conversion since the process performance deteriorated abruptly when HRT was decreased from 3.12 h to 2.88 h. In order to avoid nitrite accumulation in the reactor, the influent sulfide and nitrate concentrations should be kept at 280 mg/L and 67.5 mg/L respectively. Present biotechnology is useful for removing sulfides from sewers and crude oil.

关键词： Anaerobic processes Anoxic nitrate removal Biodesulfurization Biotransformation Fluidized bed bioreactors Hydraulic residence time (HRT)

Anoxic biodegradation of dimethyl phthalate (DMP) by activated sludge cultures under nitrate-reducing conditions

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Journal of Environmental Sciences 2007年第10期19卷 1252-1256页

作者： WU Dong-lei HU Bao-lan ZHENG Ping qaisar mahmood Department of Environmental Engineering Zhejiang University Hangzhou 310029 China

Worldwide extensive use of plasticized plastics has resulted in phthalates pollution in different environment. Nitrates from industry and agriculture are also widely disseminated in the soils, natural waters and wastewaters. Dimethyl phthalate （DMP） biodegradation by activated sludge cultures under nitrate-reducing conditions was investigated. Under one optimized condition, DMP was biodegraded from 102.20 mg/L to undetectable level in 56 h under anoxic conditions and its reaction fitted well with the first-order kinetics. Using the high-performance liquid chromatography （HPLC） and liquid chromatography mass spectrometry （LC-MS） analysis, mono-methyl phthalate （MMP） and phthalic acid （PA） were detected as the major intermediates of DMP biodegradation. When combined with the determination of chemical oxygen demand （CODer） removal capacity and pH, DMP was found to be mineralized completely under anoxic conditions. The biodegradation pathway was proposed as DMP → MMP→ PA→…→ CO2 ＋ H2O. The molar ratio of DMP to nitrate consumed was found to be 9.0：1, which agrees well with the theoretical stoichiometric values of DMP biodegradation by nitrate-reducing bacteria. The results of the non-linear simulation showed that the optimum pH and temperature for the degradation were 7.56 and 31.4℃, respectively.

关键词： biodegradation dimethyl phthalate phthalic acid nitrate reduction mineralization

Bed expansion behavior and sensitivity analysis for super-high-rate anaerobic bioreactor

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2010年第2期11卷 79-86页

作者： Xiao-guang CHEN Ping ZHENG Jing CAI mahmood qaisar Department of Environmental Engineering Zhejiang University Hangzhou 310029 China Department of Environmental Sciences COMSA TS University A bbottabad 22060 Pakistan

Bed expansion behavior and sensitivity analysis for super-high-rate anaerobic bioreactor （SAB） were performed based on bed expansion ratio （E）, maximum bed sludge content （Vpmax）, and maximum bed contact time between sludge and liquid （Tmax）. Bed expansion behavior models were established under bed unfluidization, fluidization, and transportation states. Under unfluidization state, Ewas 0, Vprnax was 4867 ml, and rmax was 844-3800 s. Under fluidization state, E, Vpmax, and Tmax were 5.28%-255.69%, 1368-4559 ml, and 104-732 s, respectively. Under transportation state, washout of granular sludge occurred and destabilized the SAB. During stable running of SAB under fluidization state, E correlated positively with superficial gas and liquid velocities （Ug and ul）, while Vpmax and Tmax correlated negatively. For E and Vpmax, the sensitivities of ug and ul were close to each other, while for Tmax, the sensitivity of ur was greater than that of Ug. The prediction from these models was a close match to the experimental data.

关键词： Anaerobic bioreactor Expansion behaviors Bed expansion ratio Fluidization state Sensitivity analysis

Production and application of anaerobic granular sludge produced by landfill

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Journal of Environmental Sciences 2007年第12期19卷 1454-1460页

作者： WANG Jin ZHANG Zhen-jia ZHANG Zhi-feng qaisar mahmood ZHENG Ping College of Environmental Science and Engineering Shanghai Jiao Tong University Shanghai 200240 Shaoxing Wastewater Treatment Development Co. Ltd. Shaoxing 312074 China Department of Environmental Engineering Zhejiang University Hangzhou 310029 China

Sludge granulation is considered to be the most critical parameter governing successful operation of an upflow anaerobic sludge blanket and expanded granular sludge bed （EGSB） reactors. Pre-granulated seeding sludge could greatly reduce the required startup time. Two lab-scale and a pilot-scale EGSB reactors were operated to treat Shaoxing Wastewater Treatment Plant （SWWTP） containing wastewater from real engineering printing and dyeing with high pH and sulfate concentration. The microbiological structure and the particle size distribution in aerobic excess sludge, sanitary landfill sludge digested for one year, and the granular sludge of EGSB reactor after 400 d of operation were analyzed through scanning electron microscopy （SEM） and sieves. The lab-scale EGSB reactor seeded with anaerobic sludge after digestion for one year in landfill showed obviously better total chemical oxygen demand （TCOD） removal efficiency than one seeded with aerobic excess sludge after cation polyacrylamide flocculation-concentration and dehydration. The TCOD removed was 470.8 mg/L in pilot scale EGSB reactor at short hydraulic retention time of 15 h. SEM of sludge granules showed that the microbiological structure of the sludge from different sources showed some differences. SEM demonstrated that Methanobacterium sp. was present in the granules of pilot-scale EGSB and the granular sludge produced by landfill contained a mixture of anaerobic/anoxic organisms in abundance. The particle size distribution in EGSB demonstrated that using anaerobic granular sludge produced by sanitary landfill as the seeding granular sludge was feasible.

关键词： anaerobic granular sludge expanded granular sludge bed (EGSB) granulation landfill seeding sludge

Nitrogen transformations during co-composting of herbal residues,spent mushrooms,and sludge

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2010年第7期11卷 497-505页

作者： Dong-lei WU Ping LIU Yan-zhang LUO Guang-ming TIAN qaisar mahmood Department of Environmental Engineering Zhejiang University Hangzhou 310029 China Department of Environmental Sciences COMSA TS University Abbottabad 22010 Pakistan

Sewage sludge composting is an important environmental measure. The reduction of nitrogen loss is a critical aim of compost maturation, and the addition of spent mushrooms (SMs) and herbal residues (HRs) may be helpful. To evaluate the nitrogen transformations during co-composting of sewage sludge, SMs, and HRs, windrows were constructed in a residual processing plant. Dewatered sewage sludge and sawdust were mixed with SMs and HRs at two proportions on a fresh weight basis, 3:1:1 (sewage sludge:sawdust:SMs or HRs) and 3:1:2 (sewage sludge:sawdust:SMs or HRs). The mixture was then composted for 40 d. Changes in the physicochemical charac- teristic of sewage sludge during composting were recorded and analyzed. Addition of SMs and HRs accelerated the temperature rise, mediating a quicker composting maturation time compared to control. The addition also resulted in lower nitrogen losses and higher nitrate nitrogen levels in the compost products. Among the windrows, SM and HR addition improved the nitrogen status. The total nitrogen (TN) and nitrogen losses for SM and HR treatments ranged from 22.45 to 24.99 g/kg and from 10.2% to 22.4% over the control values (18.66-21.57 g/kg and 40.5%-64.2%, respectively). The pile with the highest proportion of SMs (3:1:2 (sewage sludge:sawdust:SMs)) had the highest TN level and the lowest nitrogen loss. The germination index (GI) values for all samples at maturity were above 80%, demonstrating optimal maturity. The addition of SMs and HRs augments sewage composting.

关键词： Sewage sludge Spent mushrooms Herb residues Maturity Nitrogen retention Co-compost

Personal Review:Sources of sulfide in waste streams and current biotechnologies for its removal

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第7期8卷 1126-1140页

作者： mahmood qaisar ZHENG Ping CAI Jing HAYAT Yousaf HASSAN Muhammad Jaffar WU Dong-lei HU Bao-lan Department of Environmental Engmeermg Zhejiang University Hangzhou 310029 China College of Agriculture and Biotechnology Zhejiang University Hangzhou 310029 China

Sulfide-containing waste streams are generated by a number of industries. It is emitted into the environment as dis- solved sulfide (S2- and HS-) in wastewaters and as H2S in waste gases. Due to its corrosive nature, biological hydrogen sulfide removal processes are being investigated to overcome the chemical and disposal costs associated with existing chemically based removal processes. The nitrogen and sulfur metabolism interacts at various levels of the wastewater treatment process. Hence, the sulfur cycle offers possibilities to integrate nitrogen removal in the treatment process, which needs to be further optimized by appropriate design of the reactor configuration, optimization of performance parameters, retention of biomass and optimization of biomass growth. The present paper reviews the biotechnological advances to remove sulfides from various environments.

关键词： Hydrogen sulfide Sulfide utilizing microbes Nitrogen and sulfur metabolism Biotechnologies for sulfide removal

Performance,microbial community and inhibition kinetics of long-term Cu2+ stress on an air-lift nitritation reactor with self-recirculation

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Journal of Environmental Sciences 2020年第5期32卷 117-127页

作者： Fan Feng Cheng-Shan Duan Xi Tang Xi Chen Xuan Lu Xi-Lin Chai qaisar mahmood Chong-Jian Tang Li-Yuan Chai Department of Environmental Engineering School of Metallurgy and EnvironmentCentral South UniversityChangsha410083China National Engineering Research Centre for Control and Treatment of Heary Metal Pollution Changsha410083China The Jiangxi Provincial Collaborative Research Institute for Environmental Protection Industry Wannian335500China Jiangxi Gaia Environmental Science&Technology Co. Ltd.Shangrao334000China Department of Environmental Sciences COMSATS UniversityAbbottabadPakistan

Biological nitrogen removal process could be affected due to the presence of heavy metals owing to their toxicity and accumulation in the *** this study,the impact of Cu2+shock on a long-term nitritation operation was investigated in an air-lift reactor with *** the dynamics of microbial community and inhibition kinetics under Cu2+stress were *** results showed that Cu2+exerted severe inhibition on nitritation performance of an air-lift reactor(ALR)at 25 mg/*** corresponding NH4+-N removal efficiency decreased to below 50%,which was mainly due to the variation of microbial community structure,especially the inhibition of nitrifiers like Nitrosomonas(the relative abundance decreased from 30%to 1%after Cu2+inhibition).Kinetic parameters were obtained and compared after fitting the Haldane *** long-term Cu2+stress on the ALR aggravated the ammonium affinity and the resistance to substrate self-inhibition of the nitritation sludge,but reduced the resistance to Cu2+***,Cu2+acted as uncompetitive inhibitor on nitritation *** results provide new insights into the nitritation characteristics under long-term Cu2+stress.

关键词： Nitritation Cu2+inhibition Microbial structure Haldane model Kinetics