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
In order to investigate the effect of temperature on activated sludge systems,sludge settleability,nitrogen and phosphorus removal processes were investigated by changing temperature variation patterns using 4 sequenc...In order to investigate the effect of temperature on activated sludge systems,sludge settleability,nitrogen and phosphorus removal processes were investigated by changing temperature variation patterns using 4 sequencing batch reactors (SBR).The results showed that no matter temperature changes in the range of 15-22 ℃ (decrease or increase) gradually or sharply,it has little effect on nitrogen and phosphorus removal processes.But when temperature decreases to 12 ℃,biochemical reactions will be inhibitted obviously.At least 1 sludge retention time (SRT) is needed for nitrification adapt to new temperature envirionment,and more time is necessary for phosphorus removal process.When temperature increases from 12 ℃ to 22 ℃ sharply,nitrification process deteriorates seriously,but phosphorus removal process shows no change.In addition,sludge settleability deteriorates when temperature changes sharply (decrease or increase),but the reasons are different.Under temperature decrease condition,it is mainly caused by the increase of accumulated extracellular polymeric substances (EPS).Under temperature increase condition,the loosing sludge flocs' configuration is the main reason.It should be pointed out that the filamentous bacteria content during the entire experiment keeps almost constant,and the sludge settleability variations are the reflection of the change of sludge physicochemical characteristics.展开更多
Constructed wetlands with Cyperus altrnlifolius,Pennisetum sinese Roxb and elephant grass as vegetation were built to study the nitrogen and phosphorous removal from domestic sewage in cold climate.It was found that t...Constructed wetlands with Cyperus altrnlifolius,Pennisetum sinese Roxb and elephant grass as vegetation were built to study the nitrogen and phosphorous removal from domestic sewage in cold climate.It was found that these three plants could all grow slowly and stably under low temperature stress in winter,and the biomass,nitrogen and phosphorus absorption characteristics and absorbing capacity of the three plants were different.The growth rate and biomass were as follows:P.sinese Roxb>elephant grass>C.altrnlifolius,and these three plants could be used as winter wetland decontamination plants in Southwest China;the absorption characteristics of nitrogen and phosphorus in different tissues of the three plants were as follows:nitrogen content in leaf>nitrogen content in stem,phosphorus content in stem>phosphorus content in leaf;the removal of total nitrogen(TN)by three plants in the wetland was ranged form 4.3%to 7.8%,and the removal of total phosphorus(TP)was ranged from 3.3%to 5.3%.Different plants had different absorption effects on nitrogen and phosphorus.There was a significantly positive correlation between plant nitrogen and phosphorus accumulation and biomass,and nitrogen removal rate in wetland showed a significantly positive correlation with biomass.展开更多
The Sri Lankan national water authority, that is The National Water Supply and Drainage Board (NWS&DB) has taken a new wastewater treatment plant into operation at Ja Ela, North of Colombo. The plant has been in o...The Sri Lankan national water authority, that is The National Water Supply and Drainage Board (NWS&DB) has taken a new wastewater treatment plant into operation at Ja Ela, North of Colombo. The plant has been in operation since September 2011. In April 2012, it was concluded how a test of the aeration efficiency and a performance test should be carried out. The tests have been based on the actual loading of the plant and the analysis results from the daily process control. The evaluation of the aeration efficiency is not reported in this paper. The paper presents the overall performance of the water treatment part of the plant during start-up conditions, from fall 2011 through the first five months of 2012. The results from the operation are found in Table 1. An important circumstance at the plant is the current very low loading in comparison with the design load. This fact has resulted in an introduction of an intermittent mode of the aeration (nitrification) reactor. Based on operation figures, during more than a month (May 2012), it has been possible to give a realistic assessment of the overall performance. The most striking results are summarized as follows: 1) The intermittent operation has enabled an energy efficient operation of the plant. By the introduction of the intermittent aeration, the energy consumption has been reduced by around 75%, compared with the continuous operation mode;2) The plant performance during the intermittent operation has been improved with respect to virtually all important pollution variables. The most striking improvement is the discharge total P level, reflecting that a substantial enhanced biological phosphorus removal takes. The typical discharge levels found during May 2012, were compared with the earlier obtained values. It is important to underline that the loading on the plant has slightly increased during May as compared with the previous operation period.展开更多
Background:This study was conducted to determine the effects of different dietary protein levels and amino acids supplementation patterns in low protein diets on the growth performance,carcass characteristics and nitr...Background:This study was conducted to determine the effects of different dietary protein levels and amino acids supplementation patterns in low protein diets on the growth performance,carcass characteristics and nitrogen excretion in growing-finishing pigs.Forty-two barrows(25.00±0.39 kg)were randomly assigned to 7 diets.Diet 1:the high crude protein diet with balanced for 10 essential amino acids(EAAs).Diet 2:the medium crude protein diet with 2%(approx)decreased protein level of Diet 1 and balanced 10 EAAs.Diet 3:the low crude protein diet with 4%decreased protein level of Diet 1 and balanced 10 EAAs.The protein levels of Diet 4,5,6 and 7 were the same as that of Diet 3.Diet 4 was only balanced for lysine(Lys),methionine(Met),threonine(Thr)and tryptophan(Trp);Diet 5 and 6 were further supplemented with extra isoleucine(Ile)or valine(Val),respectively;Diet 7 was further supplemented with extra Ile+Val.Results:Over the 112 days trial,the reduction of dietary protein by 2%or 4%with balanced10 EAAs significantly decreased nitrogen excretion(P<0.05),but had no effects on growth performance and carcass characteristics(P>0.05).In low protein diet,Val supplementation significantly increased body weight gain at 25–50 kg phase(P<0.05),while Ile supplementation at 75–100 kg phase and 100–125 kg phase significantly reduced the ratio of feed to gain(P<0.05).No effect of different dietary protein levels and amino acids supplementation patterns in low protein diets on carcass characteristics was observed(P>0.05).The total N excretion of pigs supplemented with only Lys,Met,Thr and Trp was numerically higher than that of pigs fed with extra Ile,or Val,or Ile+Val diets.Conclusion:In low protein diet,Val is more required than Ile in the early growing phage(25–50 kg),while Ile becomes more required in the late growing and finishing phage(75–125 kg).展开更多
A laboratory-scale anaerobic-anoxic-aerobic process(A^(2)O)with a small aerobic zone and a bigger anoxic zone and biologic aerated filter(A^(2)O-BAF)system was operated to treat low carbon-to-nitrogen ratio domestic w...A laboratory-scale anaerobic-anoxic-aerobic process(A^(2)O)with a small aerobic zone and a bigger anoxic zone and biologic aerated filter(A^(2)O-BAF)system was operated to treat low carbon-to-nitrogen ratio domestic wastewater.The A^(2)O process was employed mainly for organic matter and phosphorus removal,and for denitrification.The BAF was only used for nitrification which coupled with a settling tank Compared with a conventional A^(2)O process,the suspended activated sludge in this A^(2)OBAF process contained small quantities of nitrifier,but nitrification overwhelmingly conducted in BAF.So the system successfully avoided the contradiction in sludge retention time(SRT)between nitrifying bacteria and phosphorus accumulating organisms(PAOs).Denitrifying phosphorus accumulating organisms(DPAOs)played an important role in removing up to 91%of phosphorus along with nitrogen,which indicated that the suspended activated sludge process presented a good denitrifying phosphorus removal performance.The average removal efficiency of chemical oxygen demand(COD),total nitrogen(TN),total phosphorus(TP),and NH_(4)^(+)-N were 85.56%,92.07%,81.24%and 98.7%respectively.The effluent quality consistently satisfied the national first level A effluent discharge standard of China.The average sludge volume index(SVI)was 85.4 mL·g^(-1)additionally,the volume ratio of anaerobic,anoxic and aerobic zone in A^(2)O process was also investigated,and the results demonstrated that the optimum value was 1:6:2.展开更多
In this paper,a study was conducted on the effect of polyhydroxyalkanoates(PHA)and glycogen transformations on biologic nitrogen and phosphorus removal in low dissolved oxygen(DO)systems.Two laboratory-scale sequencin...In this paper,a study was conducted on the effect of polyhydroxyalkanoates(PHA)and glycogen transformations on biologic nitrogen and phosphorus removal in low dissolved oxygen(DO)systems.Two laboratory-scale sequencing batch reactors(SBR1 and SBR2)were operating with anaerobic/aerobic(low DO,0.15-0.45 mg·L^(-1))configurations,which cultured a propionic to acetic acid ratio(molar carbon ratio)of 1.0 and 2.0,respectively.Fewer poly-3-hydroxybutyrate(PHB),total PHA,and glycogen transformations were observed with the increase of propionic/acetic acid,along with more poly-3-hydroxyvalerate(PHV)and poly-3-hydroxy-2-methyvalerate(PH2MV)shifts.The total nitrogen(TN)removal efficiency was 68%and 82%in SBR1 and SBR2,respectively.In the two SBRs,the soluble ortho-phosphate(SOP)removal efficiency was 94%and 99%,and the average sludge polyphosphate(poly-P)content(g·g-MLVSS^(-1))was 8.3%and 10.2%,respectively.Thus,the propionic to acetic acid ratio of the influent greatly influenced the PHA form and quantity,glycogen transformation,and poly-P contained in activated sludge and further determined TN and SOP removal efficiency.Moreover,significant correlations between the SOP removal rate and the(PHV+PH2MV)/PHA ratio were observed(R^(2)>0.99).Accordingly,PHA and glycogen transformations should be taken into account as key components for optimizing anaerobic/aerobic(low DO)biologic nitrogen and phosphorus removal systems.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Sponsored by the Natural Science Foundation of China (Grant No.50778005)the National Key Science and Technology Special Projects (Grant No.2008ZX07209-003,2008ZX07314-008-01)
文摘In order to investigate the effect of temperature on activated sludge systems,sludge settleability,nitrogen and phosphorus removal processes were investigated by changing temperature variation patterns using 4 sequencing batch reactors (SBR).The results showed that no matter temperature changes in the range of 15-22 ℃ (decrease or increase) gradually or sharply,it has little effect on nitrogen and phosphorus removal processes.But when temperature decreases to 12 ℃,biochemical reactions will be inhibitted obviously.At least 1 sludge retention time (SRT) is needed for nitrification adapt to new temperature envirionment,and more time is necessary for phosphorus removal process.When temperature increases from 12 ℃ to 22 ℃ sharply,nitrification process deteriorates seriously,but phosphorus removal process shows no change.In addition,sludge settleability deteriorates when temperature changes sharply (decrease or increase),but the reasons are different.Under temperature decrease condition,it is mainly caused by the increase of accumulated extracellular polymeric substances (EPS).Under temperature increase condition,the loosing sludge flocs' configuration is the main reason.It should be pointed out that the filamentous bacteria content during the entire experiment keeps almost constant,and the sludge settleability variations are the reflection of the change of sludge physicochemical characteristics.
基金Supported by Guizhou Tripartite Joint Fund(Qiankehe LH[2016]7283)Top Talent Project of Guizhou Province(Qianjiaohe KY[2016]097)Doctoral Research Start up Fund of Anshun University[(asubsjj 2016)07].
文摘Constructed wetlands with Cyperus altrnlifolius,Pennisetum sinese Roxb and elephant grass as vegetation were built to study the nitrogen and phosphorous removal from domestic sewage in cold climate.It was found that these three plants could all grow slowly and stably under low temperature stress in winter,and the biomass,nitrogen and phosphorus absorption characteristics and absorbing capacity of the three plants were different.The growth rate and biomass were as follows:P.sinese Roxb>elephant grass>C.altrnlifolius,and these three plants could be used as winter wetland decontamination plants in Southwest China;the absorption characteristics of nitrogen and phosphorus in different tissues of the three plants were as follows:nitrogen content in leaf>nitrogen content in stem,phosphorus content in stem>phosphorus content in leaf;the removal of total nitrogen(TN)by three plants in the wetland was ranged form 4.3%to 7.8%,and the removal of total phosphorus(TP)was ranged from 3.3%to 5.3%.Different plants had different absorption effects on nitrogen and phosphorus.There was a significantly positive correlation between plant nitrogen and phosphorus accumulation and biomass,and nitrogen removal rate in wetland showed a significantly positive correlation with biomass.
文摘The Sri Lankan national water authority, that is The National Water Supply and Drainage Board (NWS&DB) has taken a new wastewater treatment plant into operation at Ja Ela, North of Colombo. The plant has been in operation since September 2011. In April 2012, it was concluded how a test of the aeration efficiency and a performance test should be carried out. The tests have been based on the actual loading of the plant and the analysis results from the daily process control. The evaluation of the aeration efficiency is not reported in this paper. The paper presents the overall performance of the water treatment part of the plant during start-up conditions, from fall 2011 through the first five months of 2012. The results from the operation are found in Table 1. An important circumstance at the plant is the current very low loading in comparison with the design load. This fact has resulted in an introduction of an intermittent mode of the aeration (nitrification) reactor. Based on operation figures, during more than a month (May 2012), it has been possible to give a realistic assessment of the overall performance. The most striking results are summarized as follows: 1) The intermittent operation has enabled an energy efficient operation of the plant. By the introduction of the intermittent aeration, the energy consumption has been reduced by around 75%, compared with the continuous operation mode;2) The plant performance during the intermittent operation has been improved with respect to virtually all important pollution variables. The most striking improvement is the discharge total P level, reflecting that a substantial enhanced biological phosphorus removal takes. The typical discharge levels found during May 2012, were compared with the earlier obtained values. It is important to underline that the loading on the plant has slightly increased during May as compared with the previous operation period.
基金supported by the Grant from the Science and Technology Support Program of Sichuan Province(2015NZ0042,2016NZ006)National Key R&D Program of China(2018YFD0500605).
文摘Background:This study was conducted to determine the effects of different dietary protein levels and amino acids supplementation patterns in low protein diets on the growth performance,carcass characteristics and nitrogen excretion in growing-finishing pigs.Forty-two barrows(25.00±0.39 kg)were randomly assigned to 7 diets.Diet 1:the high crude protein diet with balanced for 10 essential amino acids(EAAs).Diet 2:the medium crude protein diet with 2%(approx)decreased protein level of Diet 1 and balanced 10 EAAs.Diet 3:the low crude protein diet with 4%decreased protein level of Diet 1 and balanced 10 EAAs.The protein levels of Diet 4,5,6 and 7 were the same as that of Diet 3.Diet 4 was only balanced for lysine(Lys),methionine(Met),threonine(Thr)and tryptophan(Trp);Diet 5 and 6 were further supplemented with extra isoleucine(Ile)or valine(Val),respectively;Diet 7 was further supplemented with extra Ile+Val.Results:Over the 112 days trial,the reduction of dietary protein by 2%or 4%with balanced10 EAAs significantly decreased nitrogen excretion(P<0.05),but had no effects on growth performance and carcass characteristics(P>0.05).In low protein diet,Val supplementation significantly increased body weight gain at 25–50 kg phase(P<0.05),while Ile supplementation at 75–100 kg phase and 100–125 kg phase significantly reduced the ratio of feed to gain(P<0.05).No effect of different dietary protein levels and amino acids supplementation patterns in low protein diets on carcass characteristics was observed(P>0.05).The total N excretion of pigs supplemented with only Lys,Met,Thr and Trp was numerically higher than that of pigs fed with extra Ile,or Val,or Ile+Val diets.Conclusion:In low protein diet,Val is more required than Ile in the early growing phage(25–50 kg),while Ile becomes more required in the late growing and finishing phage(75–125 kg).
基金This work was supported by the project of Scientific Research Base And Scientific Innovation Platform of Beijing Municipal Education Commission(No.PXM2008_014204_050843)Supported by State Key Laboratory of Urban Water Resource and Environment(HIT)(No.QAK200802).
文摘A laboratory-scale anaerobic-anoxic-aerobic process(A^(2)O)with a small aerobic zone and a bigger anoxic zone and biologic aerated filter(A^(2)O-BAF)system was operated to treat low carbon-to-nitrogen ratio domestic wastewater.The A^(2)O process was employed mainly for organic matter and phosphorus removal,and for denitrification.The BAF was only used for nitrification which coupled with a settling tank Compared with a conventional A^(2)O process,the suspended activated sludge in this A^(2)OBAF process contained small quantities of nitrifier,but nitrification overwhelmingly conducted in BAF.So the system successfully avoided the contradiction in sludge retention time(SRT)between nitrifying bacteria and phosphorus accumulating organisms(PAOs).Denitrifying phosphorus accumulating organisms(DPAOs)played an important role in removing up to 91%of phosphorus along with nitrogen,which indicated that the suspended activated sludge process presented a good denitrifying phosphorus removal performance.The average removal efficiency of chemical oxygen demand(COD),total nitrogen(TN),total phosphorus(TP),and NH_(4)^(+)-N were 85.56%,92.07%,81.24%and 98.7%respectively.The effluent quality consistently satisfied the national first level A effluent discharge standard of China.The average sludge volume index(SVI)was 85.4 mL·g^(-1)additionally,the volume ratio of anaerobic,anoxic and aerobic zone in A^(2)O process was also investigated,and the results demonstrated that the optimum value was 1:6:2.
基金This research work was supported by the Shanghai Shuguang Scholarship(No.05SG26)the Postdoctoral Foundation of China(No.20090450524).
文摘In this paper,a study was conducted on the effect of polyhydroxyalkanoates(PHA)and glycogen transformations on biologic nitrogen and phosphorus removal in low dissolved oxygen(DO)systems.Two laboratory-scale sequencing batch reactors(SBR1 and SBR2)were operating with anaerobic/aerobic(low DO,0.15-0.45 mg·L^(-1))configurations,which cultured a propionic to acetic acid ratio(molar carbon ratio)of 1.0 and 2.0,respectively.Fewer poly-3-hydroxybutyrate(PHB),total PHA,and glycogen transformations were observed with the increase of propionic/acetic acid,along with more poly-3-hydroxyvalerate(PHV)and poly-3-hydroxy-2-methyvalerate(PH2MV)shifts.The total nitrogen(TN)removal efficiency was 68%and 82%in SBR1 and SBR2,respectively.In the two SBRs,the soluble ortho-phosphate(SOP)removal efficiency was 94%and 99%,and the average sludge polyphosphate(poly-P)content(g·g-MLVSS^(-1))was 8.3%and 10.2%,respectively.Thus,the propionic to acetic acid ratio of the influent greatly influenced the PHA form and quantity,glycogen transformation,and poly-P contained in activated sludge and further determined TN and SOP removal efficiency.Moreover,significant correlations between the SOP removal rate and the(PHV+PH2MV)/PHA ratio were observed(R^(2)>0.99).Accordingly,PHA and glycogen transformations should be taken into account as key components for optimizing anaerobic/aerobic(low DO)biologic nitrogen and phosphorus removal systems.
