The bacterial diversity of activated sludge from submerged membrane bioreactor (SMBR) was investigated. A 16S rDNA clone library was generated, and 150 clones were screened using restriction fragment length polymorphi...The bacterial diversity of activated sludge from submerged membrane bioreactor (SMBR) was investigated. A 16S rDNA clone library was generated, and 150 clones were screened using restriction fragment length polymorphism (RFLP). Of the screened clones, almost full-length 16S rDNA sequences of 64 clones were sequenced. Phylogenetic tree was constructed with a database containing clone sequences from this study and bacterial rDNA sequences from NCBI for identification purposes. The 90.6% of the clones were a?l...展开更多
In this study, the effect of zeolite powder addition on submerged membrane bioreactor (SMBR) on membrane permeability, and the removals for COD, NH3-N, TN were investigated. Through the parallel operation of control...In this study, the effect of zeolite powder addition on submerged membrane bioreactor (SMBR) on membrane permeability, and the removals for COD, NH3-N, TN were investigated. Through the parallel operation of control and test systems, it was found that the zeolite powder addition could alleviate the ultra-filtration membrane fouling and enhance the membrane permeability. On the basis of experimental investigations, a concept of "protection coating layer" was proposed to illustrate the phenomenon of UF membrane fouling. In addition, the removal for COD in test system was more stable, a little higher compared to the control system. Due to the combination of nitrification and ion exchange, a more excellent removal for NH3-N in test system was obtained regardless of influent NH3-N loading rate. It was also found that a mean 25% higher TN removal took place in the test system, and ion exchange and simultaneous nitrification and de-nitrification were analyzed to be main factors. During the stable operation period, the SOURs of test zeolite powder added sludge and control activated sludge were measured to be 75 mgO2/(gMLVSS, h) and 24 mgO2/(gMLVSS, h) respectively, it meant that the zeolite powder addition could enhance the microorganism activity significantly.展开更多
To improve its limiting flux and antifouling characteristics in a submerged membrane-bioreactor (SMBR) for wastewater treatment, polypropylene hollow fiber microporous membrane (PPHFMM) was surface-modified by the...To improve its limiting flux and antifouling characteristics in a submerged membrane-bioreactor (SMBR) for wastewater treatment, polypropylene hollow fiber microporous membrane (PPHFMM) was surface-modified by the plasma-induced immobilization of poly (N-vinyl-2-pyrrolidone) (PVP) and the plasma treatment with different gases respectively. Attenuated total reflection-Fourier transform infrared spectroscopy (FT-IR/ATR), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope (FE-SEM) were used to characterize the structural and morphological changes on the membrane surface. Water contact angle was measured by the sessile drop method. It was found that the water contact angle was 128.8, 72.3, 62.7, 74.4, 79.1, 86.3, and 71.3° for the nascent, PVP-immobilized, air, 02, Ar, CO2 and H2O plasma treated PPHFMM, respectively. The SMBR was operated at fixed transmembrane pressure to determine the limiting flux for the PPHFMM before and after surface modification. Results showed that the limiting flux appeared to be 103, 159, 117, 133, 136, 121 and 152 L/(m^2· h) for the nascent, PVP-immobilized, air, O2, At, CO2 and H2O plasma treated PPHFMM, respectively. After continuous operation for about 50 h in the SMBR, the antifouling characteristics were improved to some extent.展开更多
A pilot scale test was conducted in a submerged membrane bioreactor SMBR with capacity of 10. 0 m^3/d for 120 days to treat high-strength Chinese traditional medicine wastewater. Performance of the SMBR was investigat...A pilot scale test was conducted in a submerged membrane bioreactor SMBR with capacity of 10. 0 m^3/d for 120 days to treat high-strength Chinese traditional medicine wastewater. Performance of the SMBR was investigated with a sludge retention time ( TSR ) of 50 days, a hydraulic retention time ( THR ) of 8.0 h, membrane flux of 8. 0 IV( m^2 · h) and dissolved oxygen (DO) concentration of 2. 0 - 3. 0 mg/L, respectively. It was observed that the SMBR had high capacity of COD and suspended solid (SS) removal. The influent COD concentration was fluctuated between I 000 and 5 000 mg/L, while the averaged effluent COl) concentration was only 44. 6 mg/L. The influent SS concentration was fluctuated between 1 000 and 1 600 mg/L, while little effluent SS was detected. It was found that the COD remove rate increased with mixed liquor suspended solids (MLSS) and organic loading rate (ROL). In order to obtain good-quality effluent, the operational conditions of the SMBR were suggested as follows: the temperature was controlled above 10 ℃, MLSS about 7000 mg/L, R,L under 24. 76 kg/( m^3 · d), low vacuum value and constant water flux.展开更多
Performances of submerged membrane bioreactor (SMBR) treating brewery wastewater were investigated in this study. With little variation of COD:TN:TP ratio (100:5:1) in influent, SMBR showed high removal effici...Performances of submerged membrane bioreactor (SMBR) treating brewery wastewater were investigated in this study. With little variation of COD:TN:TP ratio (100:5:1) in influent, SMBR showed high removal efficiency ( 〉 90% ) for both COD and NH4^+ - N, and it also showed a strong resistive ability for shock organics loading rate, evidenced by no obvious fluctuation for COD in the effluent when the organics loading rate suddenly increased from 0. 27 g/( gMLSS · d) to 0. 54 g/( gMLSS · d). Comparatively different with the COD removal, TN and TP removal showed a strong correlation with the growth stage of the sludge in SMBR. When the sludge was in the multiplication stage, about 45% of TN was removed and an average removal efficiency of 30% for TP was also observed. However, when the activated sludge was in the steady stage, the removal efficiency for TN decreased to about 30% , whereas, the removal efficiency for TP was very low, and sometimes even below zero. The results of GC/MS indicated that the residual organic matters in the effluent were mainly alkyl hydrocarbon with high molecular weight, and coupling with the results of electroseopic scanning, it is speculated that biomass formed at external and internal membrane fibers played an important role for the removal of small organics.展开更多
The lack and pollution of water resource make wastewater reuse necessary. The pilot scale long-term tests for submerged membrane bioreactor were conducted to treat the effluents of anaerobic or aerobic treatment proce...The lack and pollution of water resource make wastewater reuse necessary. The pilot scale long-term tests for submerged membrane bioreactor were conducted to treat the effluents of anaerobic or aerobic treatment process for the high-strength Chinese traditional medicine wastewater. This article was focused on the feasibility of the wastewater treatment and reuse at shorter hydraulic retention time (HRT) of 5.0, 3.2 and 2.13 h. MLSS growth, membrane flux, vacuum values and chemical cleaning periods were also investigated. The experimental results of treating two-phase anaerobic treatment effluent demonstrated that the CODfilt was less than 100 mg/L when the influent COD was between 500-10000 mg/L at HRT of 5.0 h, which could satisfy the normal discharged standard in China. The experimental results to treat cross flow aerobic reactor effluent demonstrated that the average value of CODfilt was 17.28 mg/L when the average value of influent COD was 192.84 mg/L at HRT of 2.13 h during 106 d, which could completely meet the normal standard for water reuse. The maximum MLSS and MLVSS reached 24000 and 14500 mg/L at HRT of 3.2 h respectively. Membrane flux had maximal resume degrees of 94.7% at vacuum value of 0.02 MPa after cleaning. Chemical cleaning periods of membrane module were 150 d. A simulation model of operational parameters was also established based on the theory of back propagation neural network and linear regression of traditional mathematical model. The simulation model showed that the optimum operational parameters were suggested as follows: HRT was 5.0 h, SRT was 100 d, the range of COD loading rate was between 10.664-20.451 kg/(m3.d), the range of MLSS was between 7543-13694 mg/L.展开更多
In order to improve removal for nitrogen in a pilot-scale submerged membrane bioreactor(SMBR),intermittent aeration was conducted,and the effect on the treatment performance under four kinds of operation condition(...In order to improve removal for nitrogen in a pilot-scale submerged membrane bioreactor(SMBR),intermittent aeration was conducted,and the effect on the treatment performance under four kinds of operation condition(run 1,continuous aeration;run 2,60/60 min aeration on/off time;run 3,60/90 min aeration on/off time;run 4,60/75 min aeration on/off time) was evaluated.The results showed that depending on the specific on/off of the aeration time ratio,removal efficiency of nitrogen could be improved significantly,and the removal rates of total nitrogen(TN) under different operation conditions were 28.0%,59.5%,66.8% and 70.7%,respectively.There were no obvious differences for removal rates for CODCr and ammonia among different operation conditions.In general,intermittent aeration could be used as a feasible way to improve treatment performance for nitrogen in the SMBR.展开更多
Adding iron salt or iron hydroxide to sludge-mixed liquor in an aeration tank of a conventional activated sludge processes(bioferric process)can simultaneously improve the sludge’s filterability and enhance the syste...Adding iron salt or iron hydroxide to sludge-mixed liquor in an aeration tank of a conventional activated sludge processes(bioferric process)can simultaneously improve the sludge’s filterability and enhance the system’s treatment capacity.In view of this,Fe(OH)3 was added to a submerged membrane bioreactor(SMBR)to enhance the removal efficiency and to mitigate membrane fouling.Bio-ferric process and SMBR were combined to create a novel process called Bioferric-SMBR.A side-by-side comparison study of Bioferric-SMBR and common SMBR dealing with dyeing wastewater was carried out.Bioferric-SMBR showed potential superiority,which could enhance removal efficien-cy,reduce membrane fouling and improve sludge character-istic.When volumetric loading rate was 25% higher than that of common SMBR,the removal efficiencies of Bioferric-SMBR on COD,dye,and NH_(4)^(+)-N were 1.0%,9.5%,and 5.2%higher than that of common SMBR,respectively.The trans-membrane pressure of Bioferric-SMBR was only 36%of that in common SMBR while its membrane flux was 25% higher than that of common SMBR.The stable running period in Bioferric-SMBR was 2.5 times of that in common SMBR when there was no surplus sludge discharged.The mixed liquor suspended solids concentration of Bioferric-SMBR was higher than that of common SMBR with more diversified kinds of microorganisms such as protozoans and metazoans.The mean particle diameter and specific oxygen uptake rate of Bioferric-SMBR were 3.10 and 1.23 times the common SMBR,respectively.展开更多
Highly hydrophobic Di 2-ethyl hexyl phthalate(DEHP) is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25 days, it can be used as an efficiency indicator ...Highly hydrophobic Di 2-ethyl hexyl phthalate(DEHP) is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25 days, it can be used as an efficiency indicator of wastewater treatment plant for the removal of hydrophobic emerging contaminants. In this study, the performance of submerged membrane bioreactor was monitored to understand the effect of DEHP on the growth of aerobic microorganisms. The data showed that the chemical oxygen demand(COD)and ammonia concentration were detected below 10 and 1.0 mg/L, respectively for operating conditions of hydraulic retention time(HRT) = 4 and 6 hr, sludge retention time(SRT) = 140 day and sludge concentration between 11.5 and 15.8 g volatile solid(VS)/L. The removal efficiency of DEHP under these conditions was higher and ranged between 91% and 98%. Results also showed that the removal efficiency of DEHP in biological treatment depended on the concentration of sludge, as adsorption is the main mechanism of its removal. For the submerged membrane bioreactor, the pore size is the pivotal factor for DEHP removal, since it determines the amount of soluble microbial products coming out of the process. Highly assimilated microorganisms increase the biodegradation rate, as 74% of inlet DEHP was biodegraded; however, the concentration of DEHP inside sludge was beyond the discharge limit. Understanding the fate of DEHP in membrane bioreactor,which is one of the most promising and futuristic treatment process could provide replacement for conventional processes to satisfy the future stricter regulations on emerging contaminants.展开更多
A novel method was developed to suppress membrane fouling in submerged membrane bioreactors. The method is based on the dielectrophoretic (DEP) motion of particles in an inhomogeneous electrical field. Using a real ...A novel method was developed to suppress membrane fouling in submerged membrane bioreactors. The method is based on the dielectrophoretic (DEP) motion of particles in an inhomogeneous electrical field. Using a real sample ofbiomass as feed, the fouling-suppression performance using DEP with different electrical field intensities (60-160 V) and different frequencies (50-1000 Hz) was investigated. The fouling-suppression performance was found to relate closely with the intensity and frequency of the electrical field. A stronger electrical field was found to better recover the filtrate flux. This is because of a stronger DEP force acting on the biomass par[ides close to the membrane's surface. Above an intensity and frequency value of 130 V and 1 kHz, respectively the permeate flux was reduced due to an electrothermal effect.展开更多
In the present research, a submerged membrane bioreactor was tested to treat domestic wastewater. Three experimental runs were conducted all with a hydraulic retention time of 5h and sludge retention times (SRTs) of 5...In the present research, a submerged membrane bioreactor was tested to treat domestic wastewater. Three experimental runs were conducted all with a hydraulic retention time of 5h and sludge retention times (SRTs) of 5, 10, and 20 d. The pollutant removal performance of the membrane bioreactor, the membrane effluent quality, and a kinetic model for sludge growth in the bioreactor were investigated. The combined process was capable of removing over 90% of both COD (chemical oxygen demand) and NH 3 N on the average. The total removal for COD was almost independent of SRT, but that for NH 3 N improved with increasing SRT. Membrane effluent quality meets the water quality standard for reuse issued by the Ministry of Construction of China. Increasing SRT causes the concentrations of suspended solids (SS) and volatile suspended solids (VSS) in the bioreactor to increase. However, the ratio of VSS/SS did not change much. Kinetic analysis showed that the sludge yield coefficient (kg VSS·kg COD -1 ) and the endogenous coefficient of microorganisms were 0.25 and 0.04d -1 , which are similar to those of the conventional activated sludge process.展开更多
基金the National NaturalScience Foundation of China (No. 39925007)the HiTech Research and Development Program (863) of China(No. 2002AA60l021)the Pilot Project of KnowledgeInnovation Program of Chinese Academy of Sciences (No.KSCX2-SW-102)
文摘The bacterial diversity of activated sludge from submerged membrane bioreactor (SMBR) was investigated. A 16S rDNA clone library was generated, and 150 clones were screened using restriction fragment length polymorphism (RFLP). Of the screened clones, almost full-length 16S rDNA sequences of 64 clones were sequenced. Phylogenetic tree was constructed with a database containing clone sequences from this study and bacterial rDNA sequences from NCBI for identification purposes. The 90.6% of the clones were a?l...
文摘In this study, the effect of zeolite powder addition on submerged membrane bioreactor (SMBR) on membrane permeability, and the removals for COD, NH3-N, TN were investigated. Through the parallel operation of control and test systems, it was found that the zeolite powder addition could alleviate the ultra-filtration membrane fouling and enhance the membrane permeability. On the basis of experimental investigations, a concept of "protection coating layer" was proposed to illustrate the phenomenon of UF membrane fouling. In addition, the removal for COD in test system was more stable, a little higher compared to the control system. Due to the combination of nitrification and ion exchange, a more excellent removal for NH3-N in test system was obtained regardless of influent NH3-N loading rate. It was also found that a mean 25% higher TN removal took place in the test system, and ion exchange and simultaneous nitrification and de-nitrification were analyzed to be main factors. During the stable operation period, the SOURs of test zeolite powder added sludge and control activated sludge were measured to be 75 mgO2/(gMLVSS, h) and 24 mgO2/(gMLVSS, h) respectively, it meant that the zeolite powder addition could enhance the microorganism activity significantly.
基金The Hi-Tech Research and Development Program (863) of China (No. 2002AA601230)
文摘To improve its limiting flux and antifouling characteristics in a submerged membrane-bioreactor (SMBR) for wastewater treatment, polypropylene hollow fiber microporous membrane (PPHFMM) was surface-modified by the plasma-induced immobilization of poly (N-vinyl-2-pyrrolidone) (PVP) and the plasma treatment with different gases respectively. Attenuated total reflection-Fourier transform infrared spectroscopy (FT-IR/ATR), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope (FE-SEM) were used to characterize the structural and morphological changes on the membrane surface. Water contact angle was measured by the sessile drop method. It was found that the water contact angle was 128.8, 72.3, 62.7, 74.4, 79.1, 86.3, and 71.3° for the nascent, PVP-immobilized, air, 02, Ar, CO2 and H2O plasma treated PPHFMM, respectively. The SMBR was operated at fixed transmembrane pressure to determine the limiting flux for the PPHFMM before and after surface modification. Results showed that the limiting flux appeared to be 103, 159, 117, 133, 136, 121 and 152 L/(m^2· h) for the nascent, PVP-immobilized, air, O2, At, CO2 and H2O plasma treated PPHFMM, respectively. After continuous operation for about 50 h in the SMBR, the antifouling characteristics were improved to some extent.
基金Sponsored by the National High Technology Research and Development Program of China(Grant No.2002AA601310).
文摘A pilot scale test was conducted in a submerged membrane bioreactor SMBR with capacity of 10. 0 m^3/d for 120 days to treat high-strength Chinese traditional medicine wastewater. Performance of the SMBR was investigated with a sludge retention time ( TSR ) of 50 days, a hydraulic retention time ( THR ) of 8.0 h, membrane flux of 8. 0 IV( m^2 · h) and dissolved oxygen (DO) concentration of 2. 0 - 3. 0 mg/L, respectively. It was observed that the SMBR had high capacity of COD and suspended solid (SS) removal. The influent COD concentration was fluctuated between I 000 and 5 000 mg/L, while the averaged effluent COl) concentration was only 44. 6 mg/L. The influent SS concentration was fluctuated between 1 000 and 1 600 mg/L, while little effluent SS was detected. It was found that the COD remove rate increased with mixed liquor suspended solids (MLSS) and organic loading rate (ROL). In order to obtain good-quality effluent, the operational conditions of the SMBR were suggested as follows: the temperature was controlled above 10 ℃, MLSS about 7000 mg/L, R,L under 24. 76 kg/( m^3 · d), low vacuum value and constant water flux.
文摘Performances of submerged membrane bioreactor (SMBR) treating brewery wastewater were investigated in this study. With little variation of COD:TN:TP ratio (100:5:1) in influent, SMBR showed high removal efficiency ( 〉 90% ) for both COD and NH4^+ - N, and it also showed a strong resistive ability for shock organics loading rate, evidenced by no obvious fluctuation for COD in the effluent when the organics loading rate suddenly increased from 0. 27 g/( gMLSS · d) to 0. 54 g/( gMLSS · d). Comparatively different with the COD removal, TN and TP removal showed a strong correlation with the growth stage of the sludge in SMBR. When the sludge was in the multiplication stage, about 45% of TN was removed and an average removal efficiency of 30% for TP was also observed. However, when the activated sludge was in the steady stage, the removal efficiency for TN decreased to about 30% , whereas, the removal efficiency for TP was very low, and sometimes even below zero. The results of GC/MS indicated that the residual organic matters in the effluent were mainly alkyl hydrocarbon with high molecular weight, and coupling with the results of electroseopic scanning, it is speculated that biomass formed at external and internal membrane fibers played an important role for the removal of small organics.
基金Project supported by the Hi-Tech Research and Development Program (863) of China (No. 2002AA601310).
文摘The lack and pollution of water resource make wastewater reuse necessary. The pilot scale long-term tests for submerged membrane bioreactor were conducted to treat the effluents of anaerobic or aerobic treatment process for the high-strength Chinese traditional medicine wastewater. This article was focused on the feasibility of the wastewater treatment and reuse at shorter hydraulic retention time (HRT) of 5.0, 3.2 and 2.13 h. MLSS growth, membrane flux, vacuum values and chemical cleaning periods were also investigated. The experimental results of treating two-phase anaerobic treatment effluent demonstrated that the CODfilt was less than 100 mg/L when the influent COD was between 500-10000 mg/L at HRT of 5.0 h, which could satisfy the normal discharged standard in China. The experimental results to treat cross flow aerobic reactor effluent demonstrated that the average value of CODfilt was 17.28 mg/L when the average value of influent COD was 192.84 mg/L at HRT of 2.13 h during 106 d, which could completely meet the normal standard for water reuse. The maximum MLSS and MLVSS reached 24000 and 14500 mg/L at HRT of 3.2 h respectively. Membrane flux had maximal resume degrees of 94.7% at vacuum value of 0.02 MPa after cleaning. Chemical cleaning periods of membrane module were 150 d. A simulation model of operational parameters was also established based on the theory of back propagation neural network and linear regression of traditional mathematical model. The simulation model showed that the optimum operational parameters were suggested as follows: HRT was 5.0 h, SRT was 100 d, the range of COD loading rate was between 10.664-20.451 kg/(m3.d), the range of MLSS was between 7543-13694 mg/L.
基金Supported by the Key Science Research Project of the Eleventh Five-Year Plan (2008ZX07106-003, 2008ZX07316-004)Tianjin Binhai New Area’s Construction Science and Technology Action Planning Project of Chinese Academy of Scienses (TJZX2-YW-07)
文摘In order to improve removal for nitrogen in a pilot-scale submerged membrane bioreactor(SMBR),intermittent aeration was conducted,and the effect on the treatment performance under four kinds of operation condition(run 1,continuous aeration;run 2,60/60 min aeration on/off time;run 3,60/90 min aeration on/off time;run 4,60/75 min aeration on/off time) was evaluated.The results showed that depending on the specific on/off of the aeration time ratio,removal efficiency of nitrogen could be improved significantly,and the removal rates of total nitrogen(TN) under different operation conditions were 28.0%,59.5%,66.8% and 70.7%,respectively.There were no obvious differences for removal rates for CODCr and ammonia among different operation conditions.In general,intermittent aeration could be used as a feasible way to improve treatment performance for nitrogen in the SMBR.
基金This study was supported by the Key Technologies Research and Development Program of Science and Technology Commission of Shanghai(Grant No.012312032).
文摘Adding iron salt or iron hydroxide to sludge-mixed liquor in an aeration tank of a conventional activated sludge processes(bioferric process)can simultaneously improve the sludge’s filterability and enhance the system’s treatment capacity.In view of this,Fe(OH)3 was added to a submerged membrane bioreactor(SMBR)to enhance the removal efficiency and to mitigate membrane fouling.Bio-ferric process and SMBR were combined to create a novel process called Bioferric-SMBR.A side-by-side comparison study of Bioferric-SMBR and common SMBR dealing with dyeing wastewater was carried out.Bioferric-SMBR showed potential superiority,which could enhance removal efficien-cy,reduce membrane fouling and improve sludge character-istic.When volumetric loading rate was 25% higher than that of common SMBR,the removal efficiencies of Bioferric-SMBR on COD,dye,and NH_(4)^(+)-N were 1.0%,9.5%,and 5.2%higher than that of common SMBR,respectively.The trans-membrane pressure of Bioferric-SMBR was only 36%of that in common SMBR while its membrane flux was 25% higher than that of common SMBR.The stable running period in Bioferric-SMBR was 2.5 times of that in common SMBR when there was no surplus sludge discharged.The mixed liquor suspended solids concentration of Bioferric-SMBR was higher than that of common SMBR with more diversified kinds of microorganisms such as protozoans and metazoans.The mean particle diameter and specific oxygen uptake rate of Bioferric-SMBR were 3.10 and 1.23 times the common SMBR,respectively.
基金the National Sciences and Engineering Research Council of Canada (NSERC Grant Number: I2IPJ 461378)
文摘Highly hydrophobic Di 2-ethyl hexyl phthalate(DEHP) is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25 days, it can be used as an efficiency indicator of wastewater treatment plant for the removal of hydrophobic emerging contaminants. In this study, the performance of submerged membrane bioreactor was monitored to understand the effect of DEHP on the growth of aerobic microorganisms. The data showed that the chemical oxygen demand(COD)and ammonia concentration were detected below 10 and 1.0 mg/L, respectively for operating conditions of hydraulic retention time(HRT) = 4 and 6 hr, sludge retention time(SRT) = 140 day and sludge concentration between 11.5 and 15.8 g volatile solid(VS)/L. The removal efficiency of DEHP under these conditions was higher and ranged between 91% and 98%. Results also showed that the removal efficiency of DEHP in biological treatment depended on the concentration of sludge, as adsorption is the main mechanism of its removal. For the submerged membrane bioreactor, the pore size is the pivotal factor for DEHP removal, since it determines the amount of soluble microbial products coming out of the process. Highly assimilated microorganisms increase the biodegradation rate, as 74% of inlet DEHP was biodegraded; however, the concentration of DEHP inside sludge was beyond the discharge limit. Understanding the fate of DEHP in membrane bioreactor,which is one of the most promising and futuristic treatment process could provide replacement for conventional processes to satisfy the future stricter regulations on emerging contaminants.
文摘A novel method was developed to suppress membrane fouling in submerged membrane bioreactors. The method is based on the dielectrophoretic (DEP) motion of particles in an inhomogeneous electrical field. Using a real sample ofbiomass as feed, the fouling-suppression performance using DEP with different electrical field intensities (60-160 V) and different frequencies (50-1000 Hz) was investigated. The fouling-suppression performance was found to relate closely with the intensity and frequency of the electrical field. A stronger electrical field was found to better recover the filtrate flux. This is because of a stronger DEP force acting on the biomass par[ides close to the membrane's surface. Above an intensity and frequency value of 130 V and 1 kHz, respectively the permeate flux was reduced due to an electrothermal effect.
文摘In the present research, a submerged membrane bioreactor was tested to treat domestic wastewater. Three experimental runs were conducted all with a hydraulic retention time of 5h and sludge retention times (SRTs) of 5, 10, and 20 d. The pollutant removal performance of the membrane bioreactor, the membrane effluent quality, and a kinetic model for sludge growth in the bioreactor were investigated. The combined process was capable of removing over 90% of both COD (chemical oxygen demand) and NH 3 N on the average. The total removal for COD was almost independent of SRT, but that for NH 3 N improved with increasing SRT. Membrane effluent quality meets the water quality standard for reuse issued by the Ministry of Construction of China. Increasing SRT causes the concentrations of suspended solids (SS) and volatile suspended solids (VSS) in the bioreactor to increase. However, the ratio of VSS/SS did not change much. Kinetic analysis showed that the sludge yield coefficient (kg VSS·kg COD -1 ) and the endogenous coefficient of microorganisms were 0.25 and 0.04d -1 , which are similar to those of the conventional activated sludge process.