A full-scale test was operated by using low dissolved oxygen activated sludge process to enhance biological nitrogen and phosphorus removal. When the influent concentrations of CODCr, TN and TP varied in a range of 35...A full-scale test was operated by using low dissolved oxygen activated sludge process to enhance biological nitrogen and phosphorus removal. When the influent concentrations of CODCr, TN and TP varied in a range of 352.9 mg/L-1338.2 mg/L, 34.4 mg/L-96.3 mg/L, and 2.21 mg/L-24.0 mg/L, the average removal efficiencies were 94.9%, 86.7% and 93.0%, respectively. During the test period of two months, effluent meas of CODCr,, BOD5, NH3-N, TN and TP were below 50 mg/L, 25 mg/L, 10 mg/L and 1.0 mg/L respectively. The low dissolved oxygen activated sludge process has a simple flow sheet, fewer facilities and high N and P removal efficiency. It is very convenient to retrofit the conventional activated sludge process with the above process.展开更多
Based on the traditional method of high concentration ammonia removal from wastewater,a mixture mainly consisting of ethyl lactate and acetic acid is used as an aid for ammonia removal by air stripping.The effect of d...Based on the traditional method of high concentration ammonia removal from wastewater,a mixture mainly consisting of ethyl lactate and acetic acid is used as an aid for ammonia removal by air stripping.The effect of dosage,the depth of air nozzle in water and other conditions for ammonia removal were investigated.The results show that under the conditions that denitrification reagent is in the dosage of 30 mg/L,pH value is 9-11,blowing depth is 400 mm,stripping time is greater than 2.5 h,and the temperature is normal(25°C),the concentration of ammonia nitrogen in wastewater can be reduced from 21006.0 mg/L to 10.6 mg/L. The ammonia nitrogen removal rate is up to 99.95%.At the temperature of 45°C,the concentration of ammonia nitrogen in wastewater can be decreased from 21006 mg/L to 0.2 mg/L.The ammonia nitrogen removal rate is up to 99.999%.When the wastewater ammonia concentration is between 800-30000 mg/L,the ammonia is air stripped under the above mentioned conditions,the residual concentration can be below 15 mg/L.The stripped ammonia can be absorbed without secondary pollution.展开更多
Responses of photosynthesis and the partition of energy utilization to high-nitrogen importation and high-light intensity in leaves of three dominant tree species of subtropical forest,including sun plant or early-suc...Responses of photosynthesis and the partition of energy utilization to high-nitrogen importation and high-light intensity in leaves of three dominant tree species of subtropical forest,including sun plant or early-successional species Schima superba,mesophyte or intermediate-successional species Canstanopsis hystrix,and shading-tolerant plant or late-successional species Cryptocarya concinna were studied by using the CO2 exchange system and chlorophyll fluorescence method.Our results showed that,regardless of plant species,net photosynthetic rate(Pn)was higher in high-nitrogen supply and high irradiance(HNHL)plants than in low-nitrogen supply and high irradiance(LNHL)plants,implying that low-nitrogen importation would limit Pn of plants grown under high irradiance.However, high-nitrogen supply and low irradiance(HNLL)plants had a lower Pn.Insignificant change of quantum yield(Fv′/Fm′)in opened PS II was found in leaves of HNHL,LNHL or HNLL plants of S.superba and C. hystrix,while a higher Fv′/Fm′occurred in HNHL plants of C.concinna in comparison with LNHL or HNLL plants.The HNHL plants of C.concinna also had a higher photochemical quantum yield(△F/Fm′) than LNHL or HNLL plants,however no similar responses were found in plants of S.superba and C. hystrix(P<0.05).In the irradiance range of 0―2000μmol photon·m -2·s -1,the fraction of energy consumed by photochemistry(φ PSII )was 18.2%in LNHL plants of S.superba which was higher than that in HNHL plants(P>0.05)and it was significantly higher than in HNLL plants(P<0.05).C.hystrix also had a similar response inφ PSII to nitrogen supply and irradiance.Regardless of species HNLL plants had a significantφ PSII and higher heat dissipation in light,and this effect was more severe in C.concinna than in S.superba or C.hystrix.The results may mean that high-nitrogen importation by nitrogen deposit and low irradiance caused by changing climate or air pollution would more severely restrict photosynthetic processes in the late-successional species C.concinna than in the early-successional species S.superba and intermediate-successional species C.hystrix.The continuous high-nitrogen precipitation in the future and the over cast mist or pollution smoke could induce late-successional species to degrade,however,early-successional species would be more adapted to competition for more resources to keep their dominance in ecosystems.In this sense,the zonal vegetation may accelerate degradation caused by high nitrogen precipitation and low irradiance,while the early-successional and mesophytic vegetations can remain longer.Thus,nitrogen precipitation may play an important role in plant community succession.展开更多
文摘A full-scale test was operated by using low dissolved oxygen activated sludge process to enhance biological nitrogen and phosphorus removal. When the influent concentrations of CODCr, TN and TP varied in a range of 352.9 mg/L-1338.2 mg/L, 34.4 mg/L-96.3 mg/L, and 2.21 mg/L-24.0 mg/L, the average removal efficiencies were 94.9%, 86.7% and 93.0%, respectively. During the test period of two months, effluent meas of CODCr,, BOD5, NH3-N, TN and TP were below 50 mg/L, 25 mg/L, 10 mg/L and 1.0 mg/L respectively. The low dissolved oxygen activated sludge process has a simple flow sheet, fewer facilities and high N and P removal efficiency. It is very convenient to retrofit the conventional activated sludge process with the above process.
基金supported by Water Pollution Control and Management of Chinese Special Key Science and Technology Project(2008ZX07101007-01)
文摘Based on the traditional method of high concentration ammonia removal from wastewater,a mixture mainly consisting of ethyl lactate and acetic acid is used as an aid for ammonia removal by air stripping.The effect of dosage,the depth of air nozzle in water and other conditions for ammonia removal were investigated.The results show that under the conditions that denitrification reagent is in the dosage of 30 mg/L,pH value is 9-11,blowing depth is 400 mm,stripping time is greater than 2.5 h,and the temperature is normal(25°C),the concentration of ammonia nitrogen in wastewater can be reduced from 21006.0 mg/L to 10.6 mg/L. The ammonia nitrogen removal rate is up to 99.95%.At the temperature of 45°C,the concentration of ammonia nitrogen in wastewater can be decreased from 21006 mg/L to 0.2 mg/L.The ammonia nitrogen removal rate is up to 99.999%.When the wastewater ammonia concentration is between 800-30000 mg/L,the ammonia is air stripped under the above mentioned conditions,the residual concentration can be below 15 mg/L.The stripped ammonia can be absorbed without secondary pollution.
基金the National Natural Science Foundation of China(Grant Nos.30428022&30770328)Provincial Natural Science Foundation of Guangdong(Grant No.07006917)Knowledge Innovation Program of the Chinese Academyof Sciences(Grant No.KZCX2-SW-133)
文摘Responses of photosynthesis and the partition of energy utilization to high-nitrogen importation and high-light intensity in leaves of three dominant tree species of subtropical forest,including sun plant or early-successional species Schima superba,mesophyte or intermediate-successional species Canstanopsis hystrix,and shading-tolerant plant or late-successional species Cryptocarya concinna were studied by using the CO2 exchange system and chlorophyll fluorescence method.Our results showed that,regardless of plant species,net photosynthetic rate(Pn)was higher in high-nitrogen supply and high irradiance(HNHL)plants than in low-nitrogen supply and high irradiance(LNHL)plants,implying that low-nitrogen importation would limit Pn of plants grown under high irradiance.However, high-nitrogen supply and low irradiance(HNLL)plants had a lower Pn.Insignificant change of quantum yield(Fv′/Fm′)in opened PS II was found in leaves of HNHL,LNHL or HNLL plants of S.superba and C. hystrix,while a higher Fv′/Fm′occurred in HNHL plants of C.concinna in comparison with LNHL or HNLL plants.The HNHL plants of C.concinna also had a higher photochemical quantum yield(△F/Fm′) than LNHL or HNLL plants,however no similar responses were found in plants of S.superba and C. hystrix(P<0.05).In the irradiance range of 0―2000μmol photon·m -2·s -1,the fraction of energy consumed by photochemistry(φ PSII )was 18.2%in LNHL plants of S.superba which was higher than that in HNHL plants(P>0.05)and it was significantly higher than in HNLL plants(P<0.05).C.hystrix also had a similar response inφ PSII to nitrogen supply and irradiance.Regardless of species HNLL plants had a significantφ PSII and higher heat dissipation in light,and this effect was more severe in C.concinna than in S.superba or C.hystrix.The results may mean that high-nitrogen importation by nitrogen deposit and low irradiance caused by changing climate or air pollution would more severely restrict photosynthetic processes in the late-successional species C.concinna than in the early-successional species S.superba and intermediate-successional species C.hystrix.The continuous high-nitrogen precipitation in the future and the over cast mist or pollution smoke could induce late-successional species to degrade,however,early-successional species would be more adapted to competition for more resources to keep their dominance in ecosystems.In this sense,the zonal vegetation may accelerate degradation caused by high nitrogen precipitation and low irradiance,while the early-successional and mesophytic vegetations can remain longer.Thus,nitrogen precipitation may play an important role in plant community succession.
