A novel floating-bed incorporated with water spinach (Ipomoea aquatica), Asiatic clam (Corbicula fluminea), and carrier media supported biofilm was developed for eutrophic water purification. The contribu- tions o...A novel floating-bed incorporated with water spinach (Ipomoea aquatica), Asiatic clam (Corbicula fluminea), and carrier media supported biofilm was developed for eutrophic water purification. The contribu- tions of each biologic component to the removals of total nitrogen (TN), total phosphorus (TP) and Chl.a were examined. The nutrient removals due to the direct uptake by either water spinach or Asiatic clam were less than 10%, suggesting a negligible role of biologic assimilation and leaving the biofilm as the indispensable biologic compo- nent in the floating-bed. Chl.a was reduced mainly by Asiatic clams via filter-feeding. Meanwhile, the digestion and excretion of Asiatic clams benefited the proliferation of nitrifying and denitrifying bacteria, resulting in the improvement of TN removal. In summary, the synergetic effects of water spinach, Asiatic clams and biofilms would promote the eutrophic water treatment performance of floating-bed in comparison with the conventional floating- bed with vegetation as the single biologic component.展开更多
With growing interest in resource recovery and/or reuse,wastematerials have been considered a promising alternative for phosphorus(P)adsorption because they are low-cost and easily accessible.Crushed autoclaved aerate...With growing interest in resource recovery and/or reuse,wastematerials have been considered a promising alternative for phosphorus(P)adsorption because they are low-cost and easily accessible.Crushed autoclaved aerated concrete(CAAC),as representative construction waste,has been extensively studied for P removal in ecological technologies such as treatment wetlands.However,most of the previous studies focused on the adsorption of orthophosphate,namely reactive phosphorus,and lacked attention to non-reactive phosphorus(NRP)which is widely present in sewage.This study presents the first investigation on the potential and mechanism of CAAC removing four model NRP compounds.Adsorption isotherm and kinetics of NRP onto CAAC indicate that the removal of NRP was a chemisorption process and also involved a two-step pore diffusion process.The desorption experiment shows that different NRP species showed varying degrees of desorption.Most NRP was irreversibly adsorbed on CAAC.Among the model compounds considered in this study,the adsorption capacity and hydrolysis rate of organophosphorus were much less than that of inorganic phosphorus.Moreover,the adsorption of different NRP species by CAAC in the mesocosm study was different from the results of laboratory adsorption experiments,and the possible biodegradation was essential for the conversion and removal of NRP.The findings confirmed the validity of CAAC for NRP removal and the potential advantages of CAAC in terms of costs and environmental impact.This study will contribute to a better understanding of NRP conversion and environmental fate and that can be the basis for a refined risk assessment.展开更多
The growth and metabolism of microbial communities on biologically activated carbon (BAC) play a crucial role in the purification of drinking water. To gain insight into the growth and metabolic characteristics of m...The growth and metabolism of microbial communities on biologically activated carbon (BAC) play a crucial role in the purification of drinking water. To gain insight into the growth and metabolic characteristics of microbial communities and the efficiency of drinking water treatment in a BAC filter, we analyzed the heterotrophic plate count (HPC), phospholipid, dehydrogenase, metabolic function and water quality parameters during start-up and steady-state periods. In the start-up process of the filter with natural biofilm colonization, the variation in heterotrophic plate count levels was S-curved. The total phospholipid level was very low during the first 5 days and reached a maximum value after 40 days in the filter. The activity of dehydrogenase gradually increased during the first 30 days and then reached a plateau. The functional diversity of the microbial community in the filter increased, and then reached a relatively stable level by day 40. After an initial decrease, which was followed by an increase, the removal rate of NH4+-N and COD_Mn became stable and was 80% and 28%, respectively, by day 40. The consumption rate of dissolved oxygen reached a steady level after 29 days, and remained at 18%. At the steady operation state, the levels of HPC, phospholipid, dehydrogenase activity and carbon source utilization had no significant differences after 6 months compared to levels measured on day 40. The filter was shown to be effective in removing NH4+-N, NO2--N, CODMn, UV254, biodegradable dissolved organic carbon and trace organic pollutants from the influent. Our results suggest that understanding changes in the growth and metabolism of microorganisms in BAC filter could help to improve the efficiency of biological treatment of drinking water.展开更多
文摘A novel floating-bed incorporated with water spinach (Ipomoea aquatica), Asiatic clam (Corbicula fluminea), and carrier media supported biofilm was developed for eutrophic water purification. The contribu- tions of each biologic component to the removals of total nitrogen (TN), total phosphorus (TP) and Chl.a were examined. The nutrient removals due to the direct uptake by either water spinach or Asiatic clam were less than 10%, suggesting a negligible role of biologic assimilation and leaving the biofilm as the indispensable biologic compo- nent in the floating-bed. Chl.a was reduced mainly by Asiatic clams via filter-feeding. Meanwhile, the digestion and excretion of Asiatic clams benefited the proliferation of nitrifying and denitrifying bacteria, resulting in the improvement of TN removal. In summary, the synergetic effects of water spinach, Asiatic clams and biofilms would promote the eutrophic water treatment performance of floating-bed in comparison with the conventional floating- bed with vegetation as the single biologic component.
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment in China(No.2017ZX07202004)。
文摘With growing interest in resource recovery and/or reuse,wastematerials have been considered a promising alternative for phosphorus(P)adsorption because they are low-cost and easily accessible.Crushed autoclaved aerated concrete(CAAC),as representative construction waste,has been extensively studied for P removal in ecological technologies such as treatment wetlands.However,most of the previous studies focused on the adsorption of orthophosphate,namely reactive phosphorus,and lacked attention to non-reactive phosphorus(NRP)which is widely present in sewage.This study presents the first investigation on the potential and mechanism of CAAC removing four model NRP compounds.Adsorption isotherm and kinetics of NRP onto CAAC indicate that the removal of NRP was a chemisorption process and also involved a two-step pore diffusion process.The desorption experiment shows that different NRP species showed varying degrees of desorption.Most NRP was irreversibly adsorbed on CAAC.Among the model compounds considered in this study,the adsorption capacity and hydrolysis rate of organophosphorus were much less than that of inorganic phosphorus.Moreover,the adsorption of different NRP species by CAAC in the mesocosm study was different from the results of laboratory adsorption experiments,and the possible biodegradation was essential for the conversion and removal of NRP.The findings confirmed the validity of CAAC for NRP removal and the potential advantages of CAAC in terms of costs and environmental impact.This study will contribute to a better understanding of NRP conversion and environmental fate and that can be the basis for a refined risk assessment.
基金supported by the National High Technology Research and Development Program (863) of China (No.2008AA06A412)the National Key Projects of Water Pollution Control and Treatment (No. 2008ZX07421-004)
文摘The growth and metabolism of microbial communities on biologically activated carbon (BAC) play a crucial role in the purification of drinking water. To gain insight into the growth and metabolic characteristics of microbial communities and the efficiency of drinking water treatment in a BAC filter, we analyzed the heterotrophic plate count (HPC), phospholipid, dehydrogenase, metabolic function and water quality parameters during start-up and steady-state periods. In the start-up process of the filter with natural biofilm colonization, the variation in heterotrophic plate count levels was S-curved. The total phospholipid level was very low during the first 5 days and reached a maximum value after 40 days in the filter. The activity of dehydrogenase gradually increased during the first 30 days and then reached a plateau. The functional diversity of the microbial community in the filter increased, and then reached a relatively stable level by day 40. After an initial decrease, which was followed by an increase, the removal rate of NH4+-N and COD_Mn became stable and was 80% and 28%, respectively, by day 40. The consumption rate of dissolved oxygen reached a steady level after 29 days, and remained at 18%. At the steady operation state, the levels of HPC, phospholipid, dehydrogenase activity and carbon source utilization had no significant differences after 6 months compared to levels measured on day 40. The filter was shown to be effective in removing NH4+-N, NO2--N, CODMn, UV254, biodegradable dissolved organic carbon and trace organic pollutants from the influent. Our results suggest that understanding changes in the growth and metabolism of microorganisms in BAC filter could help to improve the efficiency of biological treatment of drinking water.