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A DO- and pH-Based Early Warning System of Nitrification Inhibition for Biological Nitrogen Removal Processes  [PDF]
Seil Hong,Il Choi,Byung Jin Lim,Hyunook Kim
Sensors , 2012, DOI: 10.3390/s121216334
Abstract: In Korea, more than 80% of municipal wastewater treatment plants (WWTPs) with capacities of 500 m3·d?1 or more are capable of removing nitrogen from wastewater through biological nitrification and denitrification processes. Normally, these biological processes show excellent performance, but if a toxic chemical is present in the influent to a WWTP, the biological processes (especially, the nitrification process) may be affected and fail to function normally; nitrifying bacteria are known very vulnerable to toxic substances. Then, the toxic compound as well as the nitrogen in wastewater may be discharged into a receiving water body without any proper treatment. Moreover, it may take significant time for the process to return back its normal state. In this study, a DO- and pH-based strategy to identify potential nitrification inhibition was developed to detect early the inflow of toxic compounds to a biological nitrogen removal process. This strategy utilizes significant changes observed in the oxygen uptake rate and the pH profiles of the mixed liquor when the activity of nitrifying bacteria is inhibited. Using the strategy, the toxicity from test wastewater with 2.5 mg·L?1 Hg2+, 0.5 mg·L?1 allythiourea, or 0.25 mg·L?1 chloroform could be successfully detected.
Simultaneous nitrification and denitrification in step feeding biological nitrogen removal process
ZHU Gui-bing,PENG Yong-zhen,WU Shu-yun,WANG Shu-ying,XU Shi-wei,
ZHU Gui-bing
,PENG Yong-zhen,WU Shu-yun,WANG Shu-ying,XU Shi-wei

环境科学学报(英文版) , 2007,
Abstract: The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates.Biological occurrence of simultaneous nitrification and denitrifieation was verified in the aspect of nitrogen mass balance and alkalinity.The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate.In each experimental run the floe sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc.
Effect of pH on nitrification
pH和碱度对生物硝化影响的探讨

CHEN Xu-liang,ZHENG Ping,JIN Ren-cun,ZHOU Shang-xing,DING Ge-sheng,
陈旭良
,郑平,金仁村,周尚兴,丁革胜

浙江大学学报(农业与生命科学版) , 2005,
Abstract: Nitrification is an effective technology to control nitrogen pollution from wastewater.The effect of pH on nitrification and the relationship between pH and alkalinity were analyzed.It was shown that pH exerted not only a large influence on the growth and metabolism of nitrifying bacteria but also the availability and toxicity of substrates and products.To a great degree,pH restricted the performance of nitrification reactor.The alkalinity of the nitrification system was mainly contributed by carbonates present.Because of the small buffering capacity of carbonates at pH 6.5-8.5,during the nitrification process the pH to being under control tended to fluctuate markedly and measures should be taken in advance.
Short-Cut/Complete Nitrification and Denitrification in a Pilot-Scale Plant Treating Actual Domestic Wastewater
实际生活污水短程/全程硝化反硝化处理中试研究

MA Yong,CHEN Lun-qiang,PENG Yong-zhen,WU Xue-lei,
马 勇
,彭永臻,陈伦强,吴学蕾

环境科学 , 2006,
Abstract: It is realized short-cut nitrification and denitrification in an A/O pilot-scale plant treating actual domestic wastewater controlling DO concentration(0.5(mg/L)) in low level at normal temperature,the average nitrite accumulation rate reached 85% or above.Three operational modes: low DO short-cut nitrification and denitrification(Mode 1),low DO complete nitrification and denitrification(Mode 2) and high DO complete nitrification and denitrification(Mode 3) were briefly compared,based on the nitrogen removal,operating cost,sludge characteristics and operational mechanism.Experimental results showed that the Mode1 is the best modes of biological nitrogen removal,in terms of improving nitrogen removal and reducing operating cost.The net pH change in aerobic zones and anoxic zones is high for Mode 1,but the net pH change in anoxic zones is very small for Mode 3.The nitrification rate is the smallest for Mode 2,and the nitrification rate for Mode 3 is little higher than that of Mode 1;the denitrification rate for Mode1 is larger than that of Mode 3 about 15%.It is feasible using DO and pH on-line sensors to control the nitrification process.
Nitrification Potential of Soils under Pollution of a Fertilizer Plant  [cached]
Gintar? Sujetovien?
Environmental Research, Engineering and Management , 2010, DOI: 10.5755/j01.erem.53.3.87
Abstract: Nitrogen compounds found in soil in the form of mineral and organic bonds are available to microbes and plants as NO3- and NH4+, produced in consequence of ammonification, nitrification and N fixation. The laboratory experiment was conducted on samples of podzolic sandy soils. Soil samples were taken in the surroundings of a nitrogen fertilizer plant Achema, situated in the center of Lithuania. The objective of the study was to determine the effect of soil contamination on the nitrification process. Nitrification generally proceeded more rapidly in control soils than in soils under the Achema pollution. On the average, 0.004 mg NO2-N was nitrified per g N mineralized per hour in the plots under the influence of the nitrogen fertilizer producing plant pollution. In comparison with nitrified N in reference soils the values were significantly higher - 0.253 (p < 0.05). Soils from background ecosystems had, on the average, 63 times higher nitrification rate than in polluted soils. The eutrophication of pine sandy soils stimulated biological processes and that was likely related to higher soil pH and initial NH4+.
NITRIFICATION AND DENITRIFICATION IN SUBALPINE CONIFEROUS FORESTS OF DIFFERENT RESTORATION STAGES IN WESTERN SICHUAN, CHINA
川西亚高山针叶林不同恢复阶段土壤的硝化和反硝化作用

LIU Yi,CHEN Jin-Song,LIU Qing,WU Yan,
刘义
,陈劲松,刘庆,吴彦

植物生态学报 , 2006,
Abstract: Nitrification is biological conversion of organic or inorganic nitrogen compounds from a reduced a more oxidized state. Denitrification is generally referred as the microbial reduction of nitrate to nitrite and further gaseous forms of nitric oxide, nitrous oxide and molecular nitrogen. They are functionally interconnected processes in the soil nitrogen cycle that are involved in the control of long-term nitrogen losses in ecosystems through nitrate leaching and gaseous N losses. In order to better understand how nitrification and denitrification change during the process of ecosystem restoration and how they are affected by various controlling factors, gross nitrification rates and denitrification rates were determined using the barometric process separation (BaPS) technique in subalpine coniferous forests of different restoration stages. The results showed that the forest restoration stage had no significant effect on gross nitrification and denitrification rates (One-way ANOVA, p<0.05). There were no significant differences in the temperature coefficient (Q- 10 ) for gross nitrification rate among all forest types (One-way ANOVA, p<0.05). Gross nitrification rates were positively related to water content (p<0.05) but not to soil pH, organic matter, total nitrogen, or C/N ratios. Denitrification rates in all forest soils were low and not closely related to the water content, the pH value, organic matter, or total nitrogen. Nevertheless, we found that C/N ratios obviously affected denitrification rates (p< 0.05 ). Results from this research suggest that gross nitrification is more responsible for the nitrogen loss from soils as compared with denitrification.
pH modelling in aquatic systems with time-variable acid-base dissociation constants applied to the turbid, tidal Scheldt estuary
A. F. Hofmann, J. J. Middelburg, K. Soetaert,F. J. R. Meysman
Biogeosciences (BG) & Discussions (BGD) , 2009,
Abstract: A new pH modelling approach is presented that explicitly quantifies the influence of biogeochemical processes on proton cycling and pH in an aquatic ecosystem, and which accounts for time variable acid-base dissociation constants. As a case study, the method is applied to investigate proton cycling and long-term pH trends in the Scheldt estuary (SW Netherlands, N Belgium). This analysis identifies the dominant biogeochemical processes involved in proton cycling in this heterotrophic, turbid estuary. Furthermore, information on the factors controlling the longitudinal pH profile along the estuary as well as long-term pH changes are obtained. Proton production by nitrification is identified as the principal biological process governing the pH. Its acidifying effect is mainly counteracted by proton consumption due to CO2 degassing. Overall, CO2 degassing generates the largest proton turnover in the whole estuary on a yearly basis. The main driver of long-term changes in the mean estuarine pH over the period 2001 to 2004 is the decreasing freshwater flow, which influences the pH directly via a decreasing supply of dissolved inorganic carbon and alkalinity, and also indirectly, via decreasing ammonia loadings and lower nitrification rates.
Oxygen-limited autotrophic nitrification and denitrification- A novel technology for biological nitrogen removal
限氧自养硝化—反硝化生物脱氮新技术

ZHANG Dan,XU Hui,LI Xiangli,ZHANG Ying,CHEN Guanxiong,
张丹
,徐慧,李相力,张颖,陈冠雄

应用生态学报 , 2003,
Abstract: Oxygen-limited autotrophic nitrification and denitrification (OLAND) is a biological nitrogen removal process coupled with partial nitrification and anaerobic ammonium oxidation. In our study, the nitrification was blocked at nitrite stage by controlling the dissolved oxygen concentration at 0.1-0.3 mg.L-1, and then, the denitrification proceeded, with the residual ammonium at the partial nitrification stage as electron donor. As a completely autotrophic nitrification-denitrification process, the OLAND was of many advantages (e.g., low energy consumption, high nitrogen removal rate and small footprint of system), and suitable in particular for treating low COD/NH4(+)-N ratio wastewater. It has become one of the most prosperous and practicable biological nitrogen removal technologies. The recent research of OLAND was reviewed, and its microbial mechanism as well as its applicable prospect was remarked in this paper.
Effect of Hydraulic Retention Time on Nitrification in an AirLift Biological Reactor
Furtado, A.A.L.;Albuquerque, R.T.;Leite, S.G.F.;Pe?anha, R.P.;
Brazilian Journal of Chemical Engineering , 1998, DOI: 10.1590/S0104-66321998000300008
Abstract: the occurrence of nitrogenous compounds in industrial effluents at concentration levels above legal limits, is a well-known and serious pollution problem for the receiving body. the biological process for the removal of these substances, commonly referred to as ammoniacal nitrogen, is known as nitrification. bacteria involved are mainly of the genuses nitrosomonas and nitrobacter. the aim of the present work was to study the effect of the hydraulic retention time (hrt) on the efficiency of ammonia removal from a petroleum refinery effluent using activated carbon particles as a biofilm support in an airlift bioreactor. the experiments were carried out using hrts, equal to six, eight and ten hours. the results show that hrt equal to 8 and 10 hours were enough to reduce ammoniacal nitrogen concentration to levels below permited legal limits (5mg/l nh3-n). the reactor nitrifying performance was maximized at 85% removal of ammoniacal nitrogen, for a hrt equal to 10 hours.
Effect of Hydraulic Retention Time on Nitrification in an AirLift Biological Reactor  [cached]
Furtado A.A.L.,Albuquerque R.T.,Leite S.G.F.,Pe?anha R.P.
Brazilian Journal of Chemical Engineering , 1998,
Abstract: The occurrence of nitrogenous compounds in industrial effluents at concentration levels above legal limits, is a well-known and serious pollution problem for the receiving body. The biological process for the removal of these substances, commonly referred to as ammoniacal nitrogen, is known as nitrification. Bacteria involved are mainly of the genuses Nitrosomonas and Nitrobacter. The aim of the present work was to study the effect of the hydraulic retention time (HRT) on the efficiency of ammonia removal from a petroleum refinery effluent using activated carbon particles as a biofilm support in an airlift bioreactor. The experiments were carried out using HRTs, equal to six, eight and ten hours. The results show that HRT equal to 8 and 10 hours were enough to reduce ammoniacal nitrogen concentration to levels below permited legal limits (5mg/L NH3-N). The reactor nitrifying performance was maximized at 85% removal of ammoniacal nitrogen, for a HRT equal to 10 hours.
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