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
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.
