Experiments on treatment of domestic wastewater by membrane bioreactors were carried out.The results showed that this process could produce good quality effluent with low COD,turbidity and total count of bacteria.With...Experiments on treatment of domestic wastewater by membrane bioreactors were carried out.The results showed that this process could produce good quality effluent with low COD,turbidity and total count of bacteria.With intermittent operation and continuous aeration,the membrane flux was kept steady.The mechanisms of removing COD through membrane,the structure of membrane and filtration resistance were also discussed.展开更多
Three identical membrane bioreactors (MBRs) were operated over 2 years at different sludge retention time (SRT) of 10 d, 40 d and no sludge withdrawal (NS), to elucidate and quantify the effect of SRT on the slu...Three identical membrane bioreactors (MBRs) were operated over 2 years at different sludge retention time (SRT) of 10 d, 40 d and no sludge withdrawal (NS), to elucidate and quantify the effect of SRT on the sludge characteristics and membrane fouling. The hydraulic retention times of these MBRs were controlled at 12 h. With increasing SRT, the sludge concentrations in the MBRs increased, whereas the ratio of volatile suspended solid to the total solid decreased, and the size of sludge granule diminished in the meantime. A higher sludge concentration at long SRT could maintain a better organic removal efficiency, and a longer SRT was propitious to the growth of nitrifiers. The performance of these MBRs for the removal of COD and NH4^+-N did not change much with different SRTs. However, the bioactivity decreased as SRT increase. The measurement of specific oxygen uptake rates (SOUR) and fluorescence in situ hybridization (FISH) with rRNA-targeted oligonucleotide probes testified that SOUR and the proportion of the bacteria-specific probe EUB338 in all DAPI-stainable bacteria decreased with increasing SRT. The concentrations of total organic carbon, protein, polysaccharides and soluble extracellular polymeric substance (EPS) in the mixed liquor supernatant also decreased with increasing SRT. The membrane fouling rate was higher at shorter SRT, and the highest fouling rate appeared at a SRT of 10 d. Both the sludge cake layer and gel layer had contribution to the fouling resistance, but the relative contribution of the gel layer decreased as SRT increase.展开更多
A pilot scale(10 m 3/d) anoxic/oxic membrane bioreactor(A/O MBR) was tested for dyeing wastewater treatment of woolen mill without wasting sludge in 125 days operation. Results showed that the effluent quality was exc...A pilot scale(10 m 3/d) anoxic/oxic membrane bioreactor(A/O MBR) was tested for dyeing wastewater treatment of woolen mill without wasting sludge in 125 days operation. Results showed that the effluent quality was excellent, i.e. effluent COD less than 25 mg/L, BOD 5 under 5 mg/L, turbidity lower than 0 65 NTU, and colour less than 30 DT, and met with the reuse water standard of China. The removal rates of COD, BOD 5, colour, and turbidity were 92 4%, 98 4%, 74% and 98 9%, respectively. Constant flux operation mode was carried out in this study, and backwash was effective for reducing membrane fouling and maintaining constant flux. Membrane fouling had heavy impact on energy consumption. More attention should be paid on pipe selection and design for the sidestream MBR system, too.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
Chinese traditional medicine wastewater, rich in macromolecule and easy to foam in aerobic biodegradation such as Glycosides, was treated by two identical bench-scale aerobic submerged membrane bioreactors (SMBRs) o...Chinese traditional medicine wastewater, rich in macromolecule and easy to foam in aerobic biodegradation such as Glycosides, was treated by two identical bench-scale aerobic submerged membrane bioreactors (SMBRs) operated in parallel under the same feed, equipped with the same electronic control backwashing device. One was used as the control SMBR (CSMBR) while the other was dosed with powdered activated carbon (PAC) (PAC-amended SMBR, PSMBR). The backwashing interval was 5 min. One suction period was about 90 min by adjusting preestablished backwashing vacuum and pump frequency. The average flux of CSMBR during a steady periodic state of 24 d (576 h) was 5.87 L/h with average hydraulic residence time (HRT) of 5.97 h and that of PSMBR during a steady periodic state of 30 d (720 h) was 5.85 L/h with average HRT of 5.99 h. The average total chemical oxygen demand (COD) removal efficiency of CSMBR was 89.29% with average organic loading rate (OLR) at 4.16 kg COD/(m^3.d) while that of PSMBR was 89.79% with average OLR at 5.50 kg COD/(m^3.d). COD concentration in the effluent of both SMBRs achieved the second level of the general wastewater effluent standard GB8978-1996 for the raw medicine material industry (300 mg/L). Hence, SMBR with electronic control backwashing was a viable process for medium-strength Chinese traditional medicine wastewater treatment. Moreover, the increasing rates of preestablished backwashing vacuum, pump frequency, and vacuum and flux loss caused by mixed liquor in PSMBR all lagged compared to those in CSMBR; thus the actual operating time of the PSMBR system without membrane cleaning was extended by up to 1.25 times in contrast with the CSMBR system, and the average total COD removal efficiency of PSMBR was enhanced with higher average OLR.展开更多
Organic micropollutants,with high toxicity and environmental concern,are present in the landfill leachate at much lower levels than total organic constituents (chemical oxygen demand (COD),biochemical oxygen demand (B...Organic micropollutants,with high toxicity and environmental concern,are present in the landfill leachate at much lower levels than total organic constituents (chemical oxygen demand (COD),biochemical oxygen demand (BOD),or total organic carbon (TOC)),and few has been known for their behaviors in different treatment processes.In this study,occurrence and removal of 17 organochlorine pesticides (OCPs),16 polycyclic aromatic hydrocarbons (PAHs),and technical 4-nonylphenol (4-NP) in landfill leachate in a comb...展开更多
Simultaneous nitrification and denitrification (SND) effect and phosphor removal were investigated in a one-staged aerobic submerged membrane bioreactor on pilot-scale with mixed liquor suspended solids (MLSS) 19-...Simultaneous nitrification and denitrification (SND) effect and phosphor removal were investigated in a one-staged aerobic submerged membrane bioreactor on pilot-scale with mixed liquor suspended solids (MLSS) 19--20 g/L. The effects of DO concentration, sludge floc size distribution on SND were studied. Test results suggested that SND was successfully performed in the membrane bioreactor (MBR) and about 70% total nitrogen removal efficiency was achieved when DO concentration was set to 0.2-- 0.3 mg/L. The main mechanisms governing SND were the suitable sludge floc size and the low DO concentration which was caused by low oxygen transfer rate with such a high MLSS concentration in the MBR. In the meantime, phosphor removal was also studied with polymer ferric sulfate (PFS) addition and 14 mg/L dosage of PFS was proper for the MBR to remove phosphor. PFS addition also benefited the MBR operation owing to its reduction of extracellular polymer substances (EPS) of mixed liquor.展开更多
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
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
Membrane bioreactors(MBRs) are attracting global interest but the mathematical modeling of the biological performance of MBRs remains very limited. This study focuses on the modelling of a side-stream MBR system using...Membrane bioreactors(MBRs) are attracting global interest but the mathematical modeling of the biological performance of MBRs remains very limited. This study focuses on the modelling of a side-stream MBR system using Activated Sludge Model No.1(ASM1), and comparing the results with the modelling of traditional activated sludge processes. ASM1 parameters relevant for the long-term biological behaviour in MBR systems were calibrated(i.e. Y H=0.72gCOD/gCOD, Y A=0.25gCOD/gN, b H=0.25 d -1, b A=0.080 d -1 and f P=0.06), and generally agreed with the parameters in traditional activated sludge processes, with the exception that a higher autotrophic biomass decay rate was observed in the MBR. A sensitivity analysis for steady state operation and DO dynamics suggested that the biological performance of the MBR system(the sludge concentration, effluent quality and the DO dynamics) are very sensitive to the parameters(i.e. Y H, Y A, b H, b A, μ maxH and μ maxA), and influent wastewater components(X I, S S, X S, S NH).展开更多
Based on the microorganism kinetic model, the formula for computing hydraulic retention time in a membrane bioreactor system (MBR) is derived. With considering HRT as an evaluation index a combinational approach was u...Based on the microorganism kinetic model, the formula for computing hydraulic retention time in a membrane bioreactor system (MBR) is derived. With considering HRT as an evaluation index a combinational approach was used to discuss factors which have an effect on MBR. As a result, the influencing factors were listed in order from strength to weakness as: maximum specific removal rate K , saturation constant K s, maintenance coefficient m , maximum specific growth rate μ m and observed yield coefficient Y obs . Moreover, the formula was simplified, whose parameters were experimentally determined in petrochemical wastewater treatment. The simplified formula is θ=1.1(1/β-1)(K s +S)/KX 0, for petrochemical wastewater treatment K and K s equaled 0 185 and 154.2, respectively.展开更多
Removal of inorganic nitrogen (inorganic-N) from toilet wastewater, using a pilot-scale airlift external circulation membrane bioreactor (AEC-MBR) was studied. The results showed that the use of AEC-MBR with limit...Removal of inorganic nitrogen (inorganic-N) from toilet wastewater, using a pilot-scale airlift external circulation membrane bioreactor (AEC-MBR) was studied. The results showed that the use of AEC-MBR with limited addition of alkaline reagents and volumetric loading rates of inorganic-N of 0.19-0.40 kg inorganic-N/(m^3·d) helped achieve the desired nitrification and denitrification. Furthermore, the effects of pH and dissolved oxygen (DO) on inorganic-N removal were examined. Under the condition of MLSS at 1.56-2.35 g/L, BODs/ammonia nitrogen (NH4+-N) at 1.0, pH at 7.0-7.5, and DO at 1.0-2.0 mg/L, the removal efficiencies of NH4^+-N and inorganic-N were 91.5% and 70.0%, respectively, in the AEC-MBR. The cost of addition of alkaline reagent was approximately 0.5-1.5 RMB yuan/m^3, and the energy consumption was approximately 0.72 kWh/m^3 at the flux of 8 L/(m^2-h).展开更多
The influence of a Reactive Brilliant Red X-3B (RBR X-3B) dye on the peroxidase isoenzyme ofPhanerochaete chrysosporium was determined, and the biofilm structure in a white rot fungal continuous membrane bioreactor ...The influence of a Reactive Brilliant Red X-3B (RBR X-3B) dye on the peroxidase isoenzyme ofPhanerochaete chrysosporium was determined, and the biofilm structure in a white rot fungal continuous membrane bioreactor (MBR) was also investigated by scanning electron microscope (SEM). The variation of peroxidase isoenzyme and the decolorization rate in the continuous MBR were evaluated. The results showed that the 100 mg/L RBR X-3B could stimulate the production of the peroxidase isoenzyme in the shaking-flask culture. In addition, two new peroxidase isoenzyme bands with relative mobility (Rf) value of 0.27 and 0.28 appeared, but the activity was lower than the blank control of 11 d. In the continuous MBR, the system worked stably during the first 60 d, the main peroxidase isoenzyme bands existed and three new bands with Rf value of 0.10, 0.27, and 0.28 appeared. Meanwhile, the biofilm grew well and the average decolorization rate could reach 90.6%. But the bands of peroxidase isoenzyme decreased rapidly at day 65, only two bands with Rf value 0.24 and 0.26 existed, and the decolorization rate decreased to 78.3%. Therefore, 5 bottles of P. chrysosporium mycelial pellet were added into the MBR, and then the activity of the peroxidase isoenzyme and the decolorization rate had a slight recovery. Finally, the decolorization rate finally decreased to 75.2%. These results contribute to a comprehensive understanding of the variation of peroxidase isoenzyme and biofilm in continuous MBR by white rot fungi.展开更多
By a membrane bioreactor with a settle tank in long-term operation and batch experiments, the effects of floes, soluble microorganism products (SMPs) and metal ions in activated sludge liquor on membrane fouling wer...By a membrane bioreactor with a settle tank in long-term operation and batch experiments, the effects of floes, soluble microorganism products (SMPs) and metal ions in activated sludge liquor on membrane fouling were investigated. The results showed that foulants absorbed each other and formed a fouling layer as a "second membrane" influencing the permeability of the membrane. The "gel layer" caused by SMPs and "cake layer" by floes showed great differences in morphology by analysis of scanning electron microscope and atomic force microscope. The "gel layer" was more compact and of poor permeability. When the membrane flux was 40 L/(m^2·h), the rate of membrane fouling caused by supernatant (0.011 MPa/h) was greater than that by sludgc liquor (0.0063 MPa/h). SMPs played very important roles on membrane fouling. In the bulking sludge, with SMPs increasing, the rate of membrane fouling (0.0132 MPa/h) was faster. While after flocculation of the SMPs, the rate of fouling decreased to 0.0034 M Pa/h. Floes could keep holes in their overlaps. They could alleviate membrane fouling by preventing the SMPs directly attaching on membrane surface.展开更多
The wastewater treatment from brassylic acid manufacturing plant using membrane bioreactor (MBR) was studied. The membrane bioreactor consisted of batch-operation biological aeration tank and ultrafiltration evaluatio...The wastewater treatment from brassylic acid manufacturing plant using membrane bioreactor (MBR) was studied. The membrane bioreactor consisted of batch-operation biological aeration tank and ultrafiltration evaluation tank. The content of test included the affection of variation operation conditions on ultrafiltration separation, the general characteristics of MBR process, and the difference comparing with the conventional biological treatment. The results are as follows: (1) among the test membrane material, polyether sulphone (PES) membrane is more suitable for the wastewater treatment; (2) when the cutoff molecular weight is among 10000-50000, the higher the cutoff molecular weight, the bigger the water flux is in the test; (3) under the operation pressure, water flux increases accompanying with the increasing of operation pressure; (4) the paper filtered COD concentration has more affection on the water flux than the suspended solid concentration; ( 5) as they volume loading of MBR increases, the accumulation of high molecule organic substance and colloid increases, the membrane,permeate COD concentration and paper filtered COD concentration increase too, meanwhile the water flux reduces; (6) when the sludge retention time of activated sludge of MBR increases, the accumulation of high molecule organic substance and colloid reduces, the membrane permeate (:OD concentration and paper filtered COD concentration reduce too, and the water flux increases; (7) comparing with the conventional biological process, the microbial activity is higher, but the microbial species is less.展开更多
In this bench scale submerged membrane bioreactor, effect of solid retention time and hydraulic retention time on membrane fouling propensity has been studied. This experiment is carried out at different solid retenti...In this bench scale submerged membrane bioreactor, effect of solid retention time and hydraulic retention time on membrane fouling propensity has been studied. This experiment is carried out at different solid retention time of 5, 10, 30, 70 and 98 days; and fouling behavior of membrane bioreactor is investigated. Average effluent quality is found to be 88.14%-94.38%. The experiment with different hydraulic retention is carried for 3 to 4 days and fouling behavior has been investigated. The effluent quality at different hydraulic retention time of 1, 2, 3, 5, 10 and 24 hours has been investigated. This paper aims to search optimal values of solid and hydraulic retention times at which lower fouling and higher organic removal efficiency can be obtained. This study has been mainly focused on operating parameters rather than microbial structure, effect and analysis of activated sludge to membrane fouling.展开更多
The orthogonal experiments, which involves three factors: aeration intensity, suction time and suction suspended time, were designed to research membrane fouling of jet loop membrane bioreactor (JLMBR). Experimenta...The orthogonal experiments, which involves three factors: aeration intensity, suction time and suction suspended time, were designed to research membrane fouling of jet loop membrane bioreactor (JLMBR). Experimental results indicate that increasing aeration intensity, reducing suction time and increasing suction suspended time all could mitigate membrane fouling effectively. However excessive aeration intensity, too short suction time and excessive suction suspended time were bad for bioreactor running. The optimal aeration intensity, suction time and suction suspended time were 0.75 1.00 m3/(m2.h), 8 -10 min and 4 -5 min, respectively. The three factors all had effect on membrane pollution rate, while the suction time was the most important one and followed by aeration intensity and suction suspended time. It also indicates that, comparing with traditional submerged membrane bioreactors, JLMBR had lower membrane pollution rate.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
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
Nonwoven was selected as filtration materials in submerged membrane bioreactor( MBR) for domestic wastewater reclamation. For its hydrophobic membrane surface,diatomite was precoated on nonwoven to improve membrane hy...Nonwoven was selected as filtration materials in submerged membrane bioreactor( MBR) for domestic wastewater reclamation. For its hydrophobic membrane surface,diatomite was precoated on nonwoven to improve membrane hydrophilicity. In the precoating stage,diatomite dynamic membrane could be formed on10 μm polyethylene nonwoven surface efficiently and effluent turbidity could be below 5 nephelometric turbidity units( NTU).The MBR system was operated steadily under gravity flow and scanning electron microscope( SEM) analysis showed that nonwoven membrane was only partially fouled at the membrane flux of 5 L/( m2·h). Average removal efficiencies of chemical oxygen demand( COD) and NH +4-N were above 86 % and 50 %,respectively. The effluent turbidity and chromaticity were below 5 NTU and 25°,respectively. Those results could meet the requirements for wastewater reuse.展开更多
基金Supported by the Ministry of Science and Technology of China!(No.96- 92 0 - 0 9- 0 4 )
文摘Experiments on treatment of domestic wastewater by membrane bioreactors were carried out.The results showed that this process could produce good quality effluent with low COD,turbidity and total count of bacteria.With intermittent operation and continuous aeration,the membrane flux was kept steady.The mechanisms of removing COD through membrane,the structure of membrane and filtration resistance were also discussed.
基金supported by the National Natural Science Foundation of China (No 50678170)
文摘Three identical membrane bioreactors (MBRs) were operated over 2 years at different sludge retention time (SRT) of 10 d, 40 d and no sludge withdrawal (NS), to elucidate and quantify the effect of SRT on the sludge characteristics and membrane fouling. The hydraulic retention times of these MBRs were controlled at 12 h. With increasing SRT, the sludge concentrations in the MBRs increased, whereas the ratio of volatile suspended solid to the total solid decreased, and the size of sludge granule diminished in the meantime. A higher sludge concentration at long SRT could maintain a better organic removal efficiency, and a longer SRT was propitious to the growth of nitrifiers. The performance of these MBRs for the removal of COD and NH4^+-N did not change much with different SRTs. However, the bioactivity decreased as SRT increase. The measurement of specific oxygen uptake rates (SOUR) and fluorescence in situ hybridization (FISH) with rRNA-targeted oligonucleotide probes testified that SOUR and the proportion of the bacteria-specific probe EUB338 in all DAPI-stainable bacteria decreased with increasing SRT. The concentrations of total organic carbon, protein, polysaccharides and soluble extracellular polymeric substance (EPS) in the mixed liquor supernatant also decreased with increasing SRT. The membrane fouling rate was higher at shorter SRT, and the highest fouling rate appeared at a SRT of 10 d. Both the sludge cake layer and gel layer had contribution to the fouling resistance, but the relative contribution of the gel layer decreased as SRT increase.
文摘A pilot scale(10 m 3/d) anoxic/oxic membrane bioreactor(A/O MBR) was tested for dyeing wastewater treatment of woolen mill without wasting sludge in 125 days operation. Results showed that the effluent quality was excellent, i.e. effluent COD less than 25 mg/L, BOD 5 under 5 mg/L, turbidity lower than 0 65 NTU, and colour less than 30 DT, and met with the reuse water standard of China. The removal rates of COD, BOD 5, colour, and turbidity were 92 4%, 98 4%, 74% and 98 9%, respectively. Constant flux operation mode was carried out in this study, and backwash was effective for reducing membrane fouling and maintaining constant flux. Membrane fouling had heavy impact on energy consumption. More attention should be paid on pipe selection and design for the sidestream MBR system, too.
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Project supported by the Hi-Tech Research and Development Program(863)of China(No. 2002AA601310).
文摘Chinese traditional medicine wastewater, rich in macromolecule and easy to foam in aerobic biodegradation such as Glycosides, was treated by two identical bench-scale aerobic submerged membrane bioreactors (SMBRs) operated in parallel under the same feed, equipped with the same electronic control backwashing device. One was used as the control SMBR (CSMBR) while the other was dosed with powdered activated carbon (PAC) (PAC-amended SMBR, PSMBR). The backwashing interval was 5 min. One suction period was about 90 min by adjusting preestablished backwashing vacuum and pump frequency. The average flux of CSMBR during a steady periodic state of 24 d (576 h) was 5.87 L/h with average hydraulic residence time (HRT) of 5.97 h and that of PSMBR during a steady periodic state of 30 d (720 h) was 5.85 L/h with average HRT of 5.99 h. The average total chemical oxygen demand (COD) removal efficiency of CSMBR was 89.29% with average organic loading rate (OLR) at 4.16 kg COD/(m^3.d) while that of PSMBR was 89.79% with average OLR at 5.50 kg COD/(m^3.d). COD concentration in the effluent of both SMBRs achieved the second level of the general wastewater effluent standard GB8978-1996 for the raw medicine material industry (300 mg/L). Hence, SMBR with electronic control backwashing was a viable process for medium-strength Chinese traditional medicine wastewater treatment. Moreover, the increasing rates of preestablished backwashing vacuum, pump frequency, and vacuum and flux loss caused by mixed liquor in PSMBR all lagged compared to those in CSMBR; thus the actual operating time of the PSMBR system without membrane cleaning was extended by up to 1.25 times in contrast with the CSMBR system, and the average total COD removal efficiency of PSMBR was enhanced with higher average OLR.
基金the National Natural Science Foundation of China (No.50538090)the National Basic Research Program (973) of China (No.2007CB407301)ST Program of Beijing Municipality (No.D0706007040291-01).
文摘Organic micropollutants,with high toxicity and environmental concern,are present in the landfill leachate at much lower levels than total organic constituents (chemical oxygen demand (COD),biochemical oxygen demand (BOD),or total organic carbon (TOC)),and few has been known for their behaviors in different treatment processes.In this study,occurrence and removal of 17 organochlorine pesticides (OCPs),16 polycyclic aromatic hydrocarbons (PAHs),and technical 4-nonylphenol (4-NP) in landfill leachate in a comb...
基金The Hi-Tech Research and Development Program (863) of China (No. 2002AA601220)
文摘Simultaneous nitrification and denitrification (SND) effect and phosphor removal were investigated in a one-staged aerobic submerged membrane bioreactor on pilot-scale with mixed liquor suspended solids (MLSS) 19--20 g/L. The effects of DO concentration, sludge floc size distribution on SND were studied. Test results suggested that SND was successfully performed in the membrane bioreactor (MBR) and about 70% total nitrogen removal efficiency was achieved when DO concentration was set to 0.2-- 0.3 mg/L. The main mechanisms governing SND were the suitable sludge floc size and the low DO concentration which was caused by low oxygen transfer rate with such a high MLSS concentration in the MBR. In the meantime, phosphor removal was also studied with polymer ferric sulfate (PFS) addition and 14 mg/L dosage of PFS was proper for the MBR to remove phosphor. PFS addition also benefited the MBR operation owing to its reduction of extracellular polymer substances (EPS) of mixed liquor.
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...
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.
文摘Membrane bioreactors(MBRs) are attracting global interest but the mathematical modeling of the biological performance of MBRs remains very limited. This study focuses on the modelling of a side-stream MBR system using Activated Sludge Model No.1(ASM1), and comparing the results with the modelling of traditional activated sludge processes. ASM1 parameters relevant for the long-term biological behaviour in MBR systems were calibrated(i.e. Y H=0.72gCOD/gCOD, Y A=0.25gCOD/gN, b H=0.25 d -1, b A=0.080 d -1 and f P=0.06), and generally agreed with the parameters in traditional activated sludge processes, with the exception that a higher autotrophic biomass decay rate was observed in the MBR. A sensitivity analysis for steady state operation and DO dynamics suggested that the biological performance of the MBR system(the sludge concentration, effluent quality and the DO dynamics) are very sensitive to the parameters(i.e. Y H, Y A, b H, b A, μ maxH and μ maxA), and influent wastewater components(X I, S S, X S, S NH).
文摘Based on the microorganism kinetic model, the formula for computing hydraulic retention time in a membrane bioreactor system (MBR) is derived. With considering HRT as an evaluation index a combinational approach was used to discuss factors which have an effect on MBR. As a result, the influencing factors were listed in order from strength to weakness as: maximum specific removal rate K , saturation constant K s, maintenance coefficient m , maximum specific growth rate μ m and observed yield coefficient Y obs . Moreover, the formula was simplified, whose parameters were experimentally determined in petrochemical wastewater treatment. The simplified formula is θ=1.1(1/β-1)(K s +S)/KX 0, for petrochemical wastewater treatment K and K s equaled 0 185 and 154.2, respectively.
基金Project supported by the Hi-Tech Research and Development Program (863) of China (No. 2002AA601220)
文摘Removal of inorganic nitrogen (inorganic-N) from toilet wastewater, using a pilot-scale airlift external circulation membrane bioreactor (AEC-MBR) was studied. The results showed that the use of AEC-MBR with limited addition of alkaline reagents and volumetric loading rates of inorganic-N of 0.19-0.40 kg inorganic-N/(m^3·d) helped achieve the desired nitrification and denitrification. Furthermore, the effects of pH and dissolved oxygen (DO) on inorganic-N removal were examined. Under the condition of MLSS at 1.56-2.35 g/L, BODs/ammonia nitrogen (NH4+-N) at 1.0, pH at 7.0-7.5, and DO at 1.0-2.0 mg/L, the removal efficiencies of NH4^+-N and inorganic-N were 91.5% and 70.0%, respectively, in the AEC-MBR. The cost of addition of alkaline reagent was approximately 0.5-1.5 RMB yuan/m^3, and the energy consumption was approximately 0.72 kWh/m^3 at the flux of 8 L/(m^2-h).
基金supported by the National High Technology Research and Development Program (863) of China (No. 2006AA06Z331)the National Natural Science Foundation of China (No. 50278034)
文摘The influence of a Reactive Brilliant Red X-3B (RBR X-3B) dye on the peroxidase isoenzyme ofPhanerochaete chrysosporium was determined, and the biofilm structure in a white rot fungal continuous membrane bioreactor (MBR) was also investigated by scanning electron microscope (SEM). The variation of peroxidase isoenzyme and the decolorization rate in the continuous MBR were evaluated. The results showed that the 100 mg/L RBR X-3B could stimulate the production of the peroxidase isoenzyme in the shaking-flask culture. In addition, two new peroxidase isoenzyme bands with relative mobility (Rf) value of 0.27 and 0.28 appeared, but the activity was lower than the blank control of 11 d. In the continuous MBR, the system worked stably during the first 60 d, the main peroxidase isoenzyme bands existed and three new bands with Rf value of 0.10, 0.27, and 0.28 appeared. Meanwhile, the biofilm grew well and the average decolorization rate could reach 90.6%. But the bands of peroxidase isoenzyme decreased rapidly at day 65, only two bands with Rf value 0.24 and 0.26 existed, and the decolorization rate decreased to 78.3%. Therefore, 5 bottles of P. chrysosporium mycelial pellet were added into the MBR, and then the activity of the peroxidase isoenzyme and the decolorization rate had a slight recovery. Finally, the decolorization rate finally decreased to 75.2%. These results contribute to a comprehensive understanding of the variation of peroxidase isoenzyme and biofilm in continuous MBR by white rot fungi.
基金The National Basic Research Program (973) of China (No. 2004CB418505) and the Teaching and Research Award Program forOutstanding Young Teachers in Higher Education Institutions of MOE, China
文摘By a membrane bioreactor with a settle tank in long-term operation and batch experiments, the effects of floes, soluble microorganism products (SMPs) and metal ions in activated sludge liquor on membrane fouling were investigated. The results showed that foulants absorbed each other and formed a fouling layer as a "second membrane" influencing the permeability of the membrane. The "gel layer" caused by SMPs and "cake layer" by floes showed great differences in morphology by analysis of scanning electron microscope and atomic force microscope. The "gel layer" was more compact and of poor permeability. When the membrane flux was 40 L/(m^2·h), the rate of membrane fouling caused by supernatant (0.011 MPa/h) was greater than that by sludgc liquor (0.0063 MPa/h). SMPs played very important roles on membrane fouling. In the bulking sludge, with SMPs increasing, the rate of membrane fouling (0.0132 MPa/h) was faster. While after flocculation of the SMPs, the rate of fouling decreased to 0.0034 M Pa/h. Floes could keep holes in their overlaps. They could alleviate membrane fouling by preventing the SMPs directly attaching on membrane surface.
文摘The wastewater treatment from brassylic acid manufacturing plant using membrane bioreactor (MBR) was studied. The membrane bioreactor consisted of batch-operation biological aeration tank and ultrafiltration evaluation tank. The content of test included the affection of variation operation conditions on ultrafiltration separation, the general characteristics of MBR process, and the difference comparing with the conventional biological treatment. The results are as follows: (1) among the test membrane material, polyether sulphone (PES) membrane is more suitable for the wastewater treatment; (2) when the cutoff molecular weight is among 10000-50000, the higher the cutoff molecular weight, the bigger the water flux is in the test; (3) under the operation pressure, water flux increases accompanying with the increasing of operation pressure; (4) the paper filtered COD concentration has more affection on the water flux than the suspended solid concentration; ( 5) as they volume loading of MBR increases, the accumulation of high molecule organic substance and colloid increases, the membrane,permeate COD concentration and paper filtered COD concentration increase too, meanwhile the water flux reduces; (6) when the sludge retention time of activated sludge of MBR increases, the accumulation of high molecule organic substance and colloid reduces, the membrane permeate (:OD concentration and paper filtered COD concentration reduce too, and the water flux increases; (7) comparing with the conventional biological process, the microbial activity is higher, but the microbial species is less.
文摘In this bench scale submerged membrane bioreactor, effect of solid retention time and hydraulic retention time on membrane fouling propensity has been studied. This experiment is carried out at different solid retention time of 5, 10, 30, 70 and 98 days; and fouling behavior of membrane bioreactor is investigated. Average effluent quality is found to be 88.14%-94.38%. The experiment with different hydraulic retention is carried for 3 to 4 days and fouling behavior has been investigated. The effluent quality at different hydraulic retention time of 1, 2, 3, 5, 10 and 24 hours has been investigated. This paper aims to search optimal values of solid and hydraulic retention times at which lower fouling and higher organic removal efficiency can be obtained. This study has been mainly focused on operating parameters rather than microbial structure, effect and analysis of activated sludge to membrane fouling.
基金Project supported by the Cooperation Program of China and Singapore(Grant No.042307013)
文摘The orthogonal experiments, which involves three factors: aeration intensity, suction time and suction suspended time, were designed to research membrane fouling of jet loop membrane bioreactor (JLMBR). Experimental results indicate that increasing aeration intensity, reducing suction time and increasing suction suspended time all could mitigate membrane fouling effectively. However excessive aeration intensity, too short suction time and excessive suction suspended time were bad for bioreactor running. The optimal aeration intensity, suction time and suction suspended time were 0.75 1.00 m3/(m2.h), 8 -10 min and 4 -5 min, respectively. The three factors all had effect on membrane pollution rate, while the suction time was the most important one and followed by aeration intensity and suction suspended time. It also indicates that, comparing with traditional submerged membrane bioreactors, JLMBR had lower membrane pollution rate.
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.
基金China State Construction Innovation Project(No.CSCEC-2012-Z-14)Shanghai Education Research and Innovation Project,China(Nos.11ZZ176,12YZ153,and ZZGJD12052)
文摘Nonwoven was selected as filtration materials in submerged membrane bioreactor( MBR) for domestic wastewater reclamation. For its hydrophobic membrane surface,diatomite was precoated on nonwoven to improve membrane hydrophilicity. In the precoating stage,diatomite dynamic membrane could be formed on10 μm polyethylene nonwoven surface efficiently and effluent turbidity could be below 5 nephelometric turbidity units( NTU).The MBR system was operated steadily under gravity flow and scanning electron microscope( SEM) analysis showed that nonwoven membrane was only partially fouled at the membrane flux of 5 L/( m2·h). Average removal efficiencies of chemical oxygen demand( COD) and NH +4-N were above 86 % and 50 %,respectively. The effluent turbidity and chromaticity were below 5 NTU and 25°,respectively. Those results could meet the requirements for wastewater reuse.