This work aims to explore a procedure to improve biological wastewater treatment efficiency using low inten-sity ultrasound.The aerobic activated sludge from a munici-pal wastewater treatment plant was used as the exp...This work aims to explore a procedure to improve biological wastewater treatment efficiency using low inten-sity ultrasound.The aerobic activated sludge from a munici-pal wastewater treatment plant was used as the experimental material.Oxygen uptake rate(OUR)of the activated sludge(AS)was determined to indicate the changes of AS activity stimulated by ultrasound at 35 kHz for 0-40 min with ultrasonic intensities of 0-1.2 W/cm^(2).The highest OUR was observed at the ultrasonic intensity of 0.3 W/cm^(2) and an irradiation period of 10 min;more than 15%increase was achieved immediately after sonication.More significantly,the AS activity stimulated by ultrasound could last 24 h after sonication,and the AS activity achieved its peak value within 8 h after sonication,or nearly 100%higher than the initial level after sonication.Therefore,to improve the wastewater treatment efficiency of bioreactors,ultrasound with an intensity of 0.3 W/cm^(2) could be employed to irradiate a part of the AS in the bioreactor for 10 min every 8 h.展开更多
Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the eval...Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the evaluation of the performance of denitrification. The size distribution of flocs measured at different denitrification moments demonstrated a clear expansion of flocs triggered by denitrification, during which higher specific endogenous and quasi-endogenous respiration rates(SOUReand SOURq) were also observed. Furthermore,SOURqincreases exponentially with the specific denitrification rate(SDNR), suggesting that there should be a maximum SDNR in conventional activated sludge systems. Based on these findings, an index Rq/t, defined as the ratio of quasi-endogenous(OURq) to maximum respiration rate(OURt), is proposed to estimate the denitrification capacity that higher Rq/tindicates higher denitrification potential, which can be readily obtained without complex measurement or analysis, and it offers a novel and promising respirogram-based approach for denitrification estimation and control by taking measures to extend anoxic time to maintain its value at a high level within a certain range.展开更多
In this study,an anaerobic/anoxic/oxic(A^(2)O)wastewater treatment process was implemented to treat domestic wastewater with short-term atrazine addition.The results provided an evaluation on the effects of an acciden...In this study,an anaerobic/anoxic/oxic(A^(2)O)wastewater treatment process was implemented to treat domestic wastewater with short-term atrazine addition.The results provided an evaluation on the effects of an accidental pollution on the operation of a wastewater treatment plant(WWTP)in relation to Chemical Oxygen Demand(COD)and biological nutrient removal.Domestic wastewater with atrazine addition in 3 continuous days was treated when steady biological nutrient removal was achieved in the A^(2)O process.The concentrations of atrazine were 15,10,and 5 mg%L–1 on days 1,2 and 3,respectively.The results showed that atrazine addition did not affect the removal of COD.The specific NH4þoxidation rate and NO3–reduction rate decreased slightly due to the short-term atrazine addition.However,it did not affect the nitrogen removal due to the high nitrification and denitrification capacity of the system.Total nitrogen(TN)removal was steady,and more than 70%was removed during the period studied.The phosphorus removal rate was not affected by the short-term addition of atrazine under the applied experimental conditions.However,more poly-hydroxy-alkanoate(PHA)was generated and utilized during atrazine addition.The results of the oxygen uptake rate(OUR)showed that the respiration of nitrifiers decreased significantly,while the activity of carbon utilizers had no obvious change with the atrazine addition.Atrazine was not removed with the A^(2)O process,even via absorption by the activated sludge in the process of the short-term addition of atrazine.展开更多
基金This work was supported by the Ministry of Science and Technology of China(Grant No.2002DFBA0009)。
文摘This work aims to explore a procedure to improve biological wastewater treatment efficiency using low inten-sity ultrasound.The aerobic activated sludge from a munici-pal wastewater treatment plant was used as the experimental material.Oxygen uptake rate(OUR)of the activated sludge(AS)was determined to indicate the changes of AS activity stimulated by ultrasound at 35 kHz for 0-40 min with ultrasonic intensities of 0-1.2 W/cm^(2).The highest OUR was observed at the ultrasonic intensity of 0.3 W/cm^(2) and an irradiation period of 10 min;more than 15%increase was achieved immediately after sonication.More significantly,the AS activity stimulated by ultrasound could last 24 h after sonication,and the AS activity achieved its peak value within 8 h after sonication,or nearly 100%higher than the initial level after sonication.Therefore,to improve the wastewater treatment efficiency of bioreactors,ultrasound with an intensity of 0.3 W/cm^(2) could be employed to irradiate a part of the AS in the bioreactor for 10 min every 8 h.
基金supported by the National Natural Science Foundation of China (Nos. 51878539, 52070149)the Technology Innovation and Level Promotion Project of Shanghai State-owned Assets Supervision and Administration Commission (No. 2018001)。
文摘Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the evaluation of the performance of denitrification. The size distribution of flocs measured at different denitrification moments demonstrated a clear expansion of flocs triggered by denitrification, during which higher specific endogenous and quasi-endogenous respiration rates(SOUReand SOURq) were also observed. Furthermore,SOURqincreases exponentially with the specific denitrification rate(SDNR), suggesting that there should be a maximum SDNR in conventional activated sludge systems. Based on these findings, an index Rq/t, defined as the ratio of quasi-endogenous(OURq) to maximum respiration rate(OURt), is proposed to estimate the denitrification capacity that higher Rq/tindicates higher denitrification potential, which can be readily obtained without complex measurement or analysis, and it offers a novel and promising respirogram-based approach for denitrification estimation and control by taking measures to extend anoxic time to maintain its value at a high level within a certain range.
基金the National Key Science and Technology Special Projects(No.2008ZX07209-003)Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality(No.PHR20090502).
文摘In this study,an anaerobic/anoxic/oxic(A^(2)O)wastewater treatment process was implemented to treat domestic wastewater with short-term atrazine addition.The results provided an evaluation on the effects of an accidental pollution on the operation of a wastewater treatment plant(WWTP)in relation to Chemical Oxygen Demand(COD)and biological nutrient removal.Domestic wastewater with atrazine addition in 3 continuous days was treated when steady biological nutrient removal was achieved in the A^(2)O process.The concentrations of atrazine were 15,10,and 5 mg%L–1 on days 1,2 and 3,respectively.The results showed that atrazine addition did not affect the removal of COD.The specific NH4þoxidation rate and NO3–reduction rate decreased slightly due to the short-term atrazine addition.However,it did not affect the nitrogen removal due to the high nitrification and denitrification capacity of the system.Total nitrogen(TN)removal was steady,and more than 70%was removed during the period studied.The phosphorus removal rate was not affected by the short-term addition of atrazine under the applied experimental conditions.However,more poly-hydroxy-alkanoate(PHA)was generated and utilized during atrazine addition.The results of the oxygen uptake rate(OUR)showed that the respiration of nitrifiers decreased significantly,while the activity of carbon utilizers had no obvious change with the atrazine addition.Atrazine was not removed with the A^(2)O process,even via absorption by the activated sludge in the process of the short-term addition of atrazine.
