Tertiary denitrification is an effective method for nitrogen removal from wastewater. A pilot-scale biofilter packed with suspended carriers was operated for tertiary denitrification with ethanol as the organic carbon...Tertiary denitrification is an effective method for nitrogen removal from wastewater. A pilot-scale biofilter packed with suspended carriers was operated for tertiary denitrification with ethanol as the organic carbon source. Long-term performance, biokinetics of denitrification and biofilm growth were evaluated under filtration velocities of 6, 10 and 14 m/hr. The pilot-scale biofilter removed nitrate from the secondary effluent effectively, and the nitrate nitrogen（NO_3-N） removal percentage was 82%, 78% and 55% at the filtration velocities of 6, 10 and 14 m/hr, respectively. At the filtration velocities of 6 and 10 m/hr, the nitrate removal loading rate increased with increasing influent nitrate loading rates, while at the filtration velocity of 14 m/hr, the removal loading rate and the influent loading rate were uncorrelated.During denitrification, the ratio of consumed chemical oxygen demand to removed NO_3-N was 3.99-4.52 mg/mg. Under the filtration velocities of 6, 10 and 14 m/hr, the maximum denitrification rate was 3.12, 4.86 and 4.42 g N/（m^2·day）, the half-saturation constant was 2.61, 1.05 and 1.17 mg/L, and the half-order coefficient was 0.22, 0.32 and 0.24（mg/L）1/2/min,respectively. The biofilm biomass increased with increasing filtration velocity and was 2845,5124 and 7324 mg VSS/m^2 at filtration velocities of 6, 10 and 14 m/hr, respectively. The highest biofilm density was 44 mg/cm^3 at the filtration velocity of 14 m/hr. Due to the low influent loading rate, biofilm biomass and thickness were lowest at the filtration velocity of 6 m/hr.展开更多
Bacterial strains in an activated sludge aerobic reactor from a coke wastewater were found to be able to utilize thiocyanate as carbon source when the thiocyanate-containing wastewater was deprived of carbon source. T...Bacterial strains in an activated sludge aerobic reactor from a coke wastewater were found to be able to utilize thiocyanate as carbon source when the thiocyanate-containing wastewater was deprived of carbon source. This study showed that three thiocyanate-oxidizing bacterial strains, Burkholderia sp., Chryseobacterium sp., and Ralstonia sp. were isolated from the activated sludge of a coke wastewater treatment plant as evidenced by the fact that complete decomposition of thiocyanate was achieved either by coculture or individual pure culture. The thiocyanate biodegradation by the coculture occurred with an optimal pH range between 6.5 and 8.5 and an optimal temperature range between 30°C and 40°C. The biodegradation kinetics of thiocyanate was well fitted with the Andrew-Haldane model, which demonstrated a distinct substrate concentration-inhibited bacterial growth pattern. The effects of different types of additional carbon, nitrogen or sulfur sources on thiocyanate biodegradation were also investigated. Analysis of the end-products indicated that thiocyanate degradation by these strains should proceed via two pathways.展开更多
为了解误吸含铀化合物气溶胶后放射性铀在体内的分布滞留情况,本研究基于国际放射防护委员会(International Commission on Radiological Protection,ICRP)130号报告给出的生物动力学模型,使用MATLAB软件中Simulink仿真工具建立人呼吸...为了解误吸含铀化合物气溶胶后放射性铀在体内的分布滞留情况,本研究基于国际放射防护委员会(International Commission on Radiological Protection,ICRP)130号报告给出的生物动力学模型,使用MATLAB软件中Simulink仿真工具建立人呼吸道隔室沉积及廓清仿真模型,并进行模拟计算。结果显示:含铀化合物的体内滞留廓清情况主要与吸入化合物的溶解度相关,溶解度高的化合物如UF6,数天后即从肺中彻底廓清,而难溶性化合物如UO2,将在肺中滞留20余年。本模型能准确反映铀在体内的滞留分布状况,可用于吸入性内污染发生后放射性铀肺部滞留量计算以及制定后续医疗救助方案。展开更多
效率校准是人体内照射活体监测中的一个关键环节,是影响内污染活体测量准确性的一个重要因素。利用人体躯干物理模型的CT扫描图片和实验确定的探测器晶体尺寸,分别建立了三维人体数字模型和高纯锗探测器的计算模型,进而通过调用Geant4...效率校准是人体内照射活体监测中的一个关键环节,是影响内污染活体测量准确性的一个重要因素。利用人体躯干物理模型的CT扫描图片和实验确定的探测器晶体尺寸,分别建立了三维人体数字模型和高纯锗探测器的计算模型,进而通过调用Geant4工具包,编写了模拟肺部计数器的蒙特卡罗程序,用以校准计数器效率。在此基础上,结合ICRP生物动力学模型,模拟计算全身其他器官滞留核素对肺部计数器计数的贡献,研究核素在其他器官的分布对计数器效率的影响。结果表明:肺部计数器效率的蒙特卡罗校准结果与实验测量结果相对偏差为2.47%(对59.5 ke V)和-8.58%(对17.5 ke V);在摄入核素241Am的最初2天内和50天后,人体的实际探测效率要高于只考虑肺部滞留的探测效率,在其他器官分布的核素在肺部计数器的计数占总计数的60%以上,而在摄入中期(第3—50天),二者结果较为一致,AMAD为1μm时,其他器官内核素的计数小于20%,AMAD为5μm时,其他器官内核素的计数在30%以内。展开更多
A pilot scale fixed bed biofilm reactor used for treating municipal wastewater was modelled to examine greenhouse gas emissions under different operational parameters. For the calculations, GPS-X 6.3 commercial simula...A pilot scale fixed bed biofilm reactor used for treating municipal wastewater was modelled to examine greenhouse gas emissions under different operational parameters. For the calculations, GPS-X 6.3 commercial simulation tool was applied, which coupled the biokinetic modelling with a GHG estimator. Model calibration was based on a twelve-day set of measurements, where the system was operated under near steady-state condition. Simulation results reflected that direct emissions from biological processes are more significant than indirect emissions originating from energy consumption. Optimizing the operational parameters of a wastewater treatment system, a significant amount of GHG emission can be spared （e.g. optimal setup for internal recycle flow and dissolved oxygen levels）, whereas, environmental factors such as temperature can also have a remarkable effect on GHG emissions： rising temperature causes faster biological reactions, increasing the production of greenhouse gases, especially methane, from the inner layers of the thick biofilm.展开更多
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China (No. 2012ZX07302002)
文摘Tertiary denitrification is an effective method for nitrogen removal from wastewater. A pilot-scale biofilter packed with suspended carriers was operated for tertiary denitrification with ethanol as the organic carbon source. Long-term performance, biokinetics of denitrification and biofilm growth were evaluated under filtration velocities of 6, 10 and 14 m/hr. The pilot-scale biofilter removed nitrate from the secondary effluent effectively, and the nitrate nitrogen（NO_3-N） removal percentage was 82%, 78% and 55% at the filtration velocities of 6, 10 and 14 m/hr, respectively. At the filtration velocities of 6 and 10 m/hr, the nitrate removal loading rate increased with increasing influent nitrate loading rates, while at the filtration velocity of 14 m/hr, the removal loading rate and the influent loading rate were uncorrelated.During denitrification, the ratio of consumed chemical oxygen demand to removed NO_3-N was 3.99-4.52 mg/mg. Under the filtration velocities of 6, 10 and 14 m/hr, the maximum denitrification rate was 3.12, 4.86 and 4.42 g N/（m^2·day）, the half-saturation constant was 2.61, 1.05 and 1.17 mg/L, and the half-order coefficient was 0.22, 0.32 and 0.24（mg/L）1/2/min,respectively. The biofilm biomass increased with increasing filtration velocity and was 2845,5124 and 7324 mg VSS/m^2 at filtration velocities of 6, 10 and 14 m/hr, respectively. The highest biofilm density was 44 mg/cm^3 at the filtration velocity of 14 m/hr. Due to the low influent loading rate, biofilm biomass and thickness were lowest at the filtration velocity of 6 m/hr.
文摘Bacterial strains in an activated sludge aerobic reactor from a coke wastewater were found to be able to utilize thiocyanate as carbon source when the thiocyanate-containing wastewater was deprived of carbon source. This study showed that three thiocyanate-oxidizing bacterial strains, Burkholderia sp., Chryseobacterium sp., and Ralstonia sp. were isolated from the activated sludge of a coke wastewater treatment plant as evidenced by the fact that complete decomposition of thiocyanate was achieved either by coculture or individual pure culture. The thiocyanate biodegradation by the coculture occurred with an optimal pH range between 6.5 and 8.5 and an optimal temperature range between 30°C and 40°C. The biodegradation kinetics of thiocyanate was well fitted with the Andrew-Haldane model, which demonstrated a distinct substrate concentration-inhibited bacterial growth pattern. The effects of different types of additional carbon, nitrogen or sulfur sources on thiocyanate biodegradation were also investigated. Analysis of the end-products indicated that thiocyanate degradation by these strains should proceed via two pathways.
文摘为了解误吸含铀化合物气溶胶后放射性铀在体内的分布滞留情况,本研究基于国际放射防护委员会(International Commission on Radiological Protection,ICRP)130号报告给出的生物动力学模型,使用MATLAB软件中Simulink仿真工具建立人呼吸道隔室沉积及廓清仿真模型,并进行模拟计算。结果显示:含铀化合物的体内滞留廓清情况主要与吸入化合物的溶解度相关,溶解度高的化合物如UF6,数天后即从肺中彻底廓清,而难溶性化合物如UO2,将在肺中滞留20余年。本模型能准确反映铀在体内的滞留分布状况,可用于吸入性内污染发生后放射性铀肺部滞留量计算以及制定后续医疗救助方案。
文摘效率校准是人体内照射活体监测中的一个关键环节,是影响内污染活体测量准确性的一个重要因素。利用人体躯干物理模型的CT扫描图片和实验确定的探测器晶体尺寸,分别建立了三维人体数字模型和高纯锗探测器的计算模型,进而通过调用Geant4工具包,编写了模拟肺部计数器的蒙特卡罗程序,用以校准计数器效率。在此基础上,结合ICRP生物动力学模型,模拟计算全身其他器官滞留核素对肺部计数器计数的贡献,研究核素在其他器官的分布对计数器效率的影响。结果表明:肺部计数器效率的蒙特卡罗校准结果与实验测量结果相对偏差为2.47%(对59.5 ke V)和-8.58%(对17.5 ke V);在摄入核素241Am的最初2天内和50天后,人体的实际探测效率要高于只考虑肺部滞留的探测效率,在其他器官分布的核素在肺部计数器的计数占总计数的60%以上,而在摄入中期(第3—50天),二者结果较为一致,AMAD为1μm时,其他器官内核素的计数小于20%,AMAD为5μm时,其他器官内核素的计数在30%以内。
文摘A pilot scale fixed bed biofilm reactor used for treating municipal wastewater was modelled to examine greenhouse gas emissions under different operational parameters. For the calculations, GPS-X 6.3 commercial simulation tool was applied, which coupled the biokinetic modelling with a GHG estimator. Model calibration was based on a twelve-day set of measurements, where the system was operated under near steady-state condition. Simulation results reflected that direct emissions from biological processes are more significant than indirect emissions originating from energy consumption. Optimizing the operational parameters of a wastewater treatment system, a significant amount of GHG emission can be spared （e.g. optimal setup for internal recycle flow and dissolved oxygen levels）, whereas, environmental factors such as temperature can also have a remarkable effect on GHG emissions： rising temperature causes faster biological reactions, increasing the production of greenhouse gases, especially methane, from the inner layers of the thick biofilm.
