Login
Register
E-alert
2021 Vol. 39, No. 7
Display Method:
2021, 39(7): 1-12.
doi: 10.13205/j.hjgc.202107001
Abstract:
In recent years, nanofiltration(NF) membranes have been extensively applied in water treatment and water reuse, such as drinking water treatment, seawater pretreatment, brackish water treatment and industrial water treatment, because of their relatively higher water permeance, selectivity and lower operation pressure. However, conventional commercial NF membranes have high rejection of minerals that are beneficial for human body at certain concentration and low rejection against harmful contaminants. In addition, the separation performance of conventional NF membrane is constrained by permeability-selectivity trade-off, known as the upper bound. This paper systematically summarizes the recent progress of nanofiltration based on its structural optimization and various modifications. Furthermore, it highlights the recent progress for modifying NF membranes focusing on optimizing porosity, hydrophilicity, surface functionalization, as well as manupulating membrane charge to improve membrane permselectivity, anti(bio)fouling and antichlorine properties. The future development trend of novel NF membranes in the context of water/waste water treatment and water reuse is also discussed.
In recent years, nanofiltration(NF) membranes have been extensively applied in water treatment and water reuse, such as drinking water treatment, seawater pretreatment, brackish water treatment and industrial water treatment, because of their relatively higher water permeance, selectivity and lower operation pressure. However, conventional commercial NF membranes have high rejection of minerals that are beneficial for human body at certain concentration and low rejection against harmful contaminants. In addition, the separation performance of conventional NF membrane is constrained by permeability-selectivity trade-off, known as the upper bound. This paper systematically summarizes the recent progress of nanofiltration based on its structural optimization and various modifications. Furthermore, it highlights the recent progress for modifying NF membranes focusing on optimizing porosity, hydrophilicity, surface functionalization, as well as manupulating membrane charge to improve membrane permselectivity, anti(bio)fouling and antichlorine properties. The future development trend of novel NF membranes in the context of water/waste water treatment and water reuse is also discussed.
2021, 39(7): 13-29,191.
doi: 10.13205/j.hjgc.202107002
Abstract:
In the emerging field of environmental protection, the research of membrane distillation(MD) has been expanding and deepening in recent years, and the industrial chain of MD has been gradually formed. This paper focused on the research progress of hydrophobic membrane, membrane module, integrated process, and application of MD, summarizing the research status and development direction of MD in the recent decade. From the perspective of hydrophobic membrane preparation, the preparation methods of the hydrophobic membrane with high flux, high strength, anti-wetting and anti-pollution were discussed. For MD module design, the MD process strengthening strategies such as membrane module structure optimization, internal/external field assistance, and membrane module design with stable, high efficiency and low energy consumption were critically surveyed. The typical MD integrated process, cleaner production process, application scenarios, and industrialization status in China and overseas were also summarized in the view of integrated process and application.
In the emerging field of environmental protection, the research of membrane distillation(MD) has been expanding and deepening in recent years, and the industrial chain of MD has been gradually formed. This paper focused on the research progress of hydrophobic membrane, membrane module, integrated process, and application of MD, summarizing the research status and development direction of MD in the recent decade. From the perspective of hydrophobic membrane preparation, the preparation methods of the hydrophobic membrane with high flux, high strength, anti-wetting and anti-pollution were discussed. For MD module design, the MD process strengthening strategies such as membrane module structure optimization, internal/external field assistance, and membrane module design with stable, high efficiency and low energy consumption were critically surveyed. The typical MD integrated process, cleaner production process, application scenarios, and industrialization status in China and overseas were also summarized in the view of integrated process and application.
2021, 39(7): 30-37,115.
doi: 10.13205/j.hjgc.202107003
Abstract:
The recovery of resource and energy in sewage and wastewater is an important part of building a low-carbon society. Electro-driven membrane separation is an effective way to realize the resource utilization of sewage and wastewater, which combines electrochemistry with membrane separation technology, and enhances membrane separation effect by adjusting electric field or electrode potential. And it is expected to break through the technical bottlenecks of membrane fouling, weak selective separation and trade-off effect. The concept of electro-driven membrane separation was proposed for the first time, and the electro-driven membrane separation was divided into electrical control membrane separation, electrodialysis and membrane capacitance deionization. This paper focused on the recovery of valuable substances in wastewater via selective membrane separation, so as to realize the recycling of wastewater. Firstly, the basic research progress of electro-driven membrane separation technology was introduced. Then, the research progress of electro-controlled membrane separation, electrodialysis and membrane capacitor deionization was reviewed and summarized from the perspectives of membrane/electrode material innovation and process optimization. Finally, the future development direction of the technology was prospected from three aspects:basic research, material innovation and reactor development.
The recovery of resource and energy in sewage and wastewater is an important part of building a low-carbon society. Electro-driven membrane separation is an effective way to realize the resource utilization of sewage and wastewater, which combines electrochemistry with membrane separation technology, and enhances membrane separation effect by adjusting electric field or electrode potential. And it is expected to break through the technical bottlenecks of membrane fouling, weak selective separation and trade-off effect. The concept of electro-driven membrane separation was proposed for the first time, and the electro-driven membrane separation was divided into electrical control membrane separation, electrodialysis and membrane capacitance deionization. This paper focused on the recovery of valuable substances in wastewater via selective membrane separation, so as to realize the recycling of wastewater. Firstly, the basic research progress of electro-driven membrane separation technology was introduced. Then, the research progress of electro-controlled membrane separation, electrodialysis and membrane capacitor deionization was reviewed and summarized from the perspectives of membrane/electrode material innovation and process optimization. Finally, the future development direction of the technology was prospected from three aspects:basic research, material innovation and reactor development.
2021, 39(7): 38-45.
doi: 10.13205/j.hjgc.202107004
Abstract:
Membrane aerated biofilm reactor(MABR) is a novel type of biological wastewater treatment technology, which has high oxygen transfer efficiency and biofilm system of counter-diffusion. It has obvious advantages in nitrogen removing efficiency, energy saving, sludge reduction, attracting much attention in recent years. In the past 20 years, a series of researches were carried out on the factors influencing the operation effect of MABR, such as gas transfer, substrate transfer and microbial community structure, and great progress was achieved in process optimization, reactor design and model simulation. With the continuous improvement of membrane materials, MABR technology has a good prospect in engineering practice.
Membrane aerated biofilm reactor(MABR) is a novel type of biological wastewater treatment technology, which has high oxygen transfer efficiency and biofilm system of counter-diffusion. It has obvious advantages in nitrogen removing efficiency, energy saving, sludge reduction, attracting much attention in recent years. In the past 20 years, a series of researches were carried out on the factors influencing the operation effect of MABR, such as gas transfer, substrate transfer and microbial community structure, and great progress was achieved in process optimization, reactor design and model simulation. With the continuous improvement of membrane materials, MABR technology has a good prospect in engineering practice.
2021, 39(7): 46-53,45.
doi: 10.13205/j.hjgc.202107005
Abstract:
In view of the membrane fouling issue commonly occurred during water treatment by nanofiltration and reverse osmosis membranes, the effects of membrane surface hydrophilicity, charge properties, functional groups and roughness on fouling behaviors were discussed for different fouling types including organic fouling, inorganic fouling, scaling and biofouling. The inconsistent results of the previous studies due to the coupling feature of membrane surface properties and the distinct characteristics of foulants were analyzed. Finally, the mechanisms and uncertainty of the influence of membrane surface properties on fouling were summarized. Suggestions were also provided for future related researches and the development of antifouling membranes.
In view of the membrane fouling issue commonly occurred during water treatment by nanofiltration and reverse osmosis membranes, the effects of membrane surface hydrophilicity, charge properties, functional groups and roughness on fouling behaviors were discussed for different fouling types including organic fouling, inorganic fouling, scaling and biofouling. The inconsistent results of the previous studies due to the coupling feature of membrane surface properties and the distinct characteristics of foulants were analyzed. Finally, the mechanisms and uncertainty of the influence of membrane surface properties on fouling were summarized. Suggestions were also provided for future related researches and the development of antifouling membranes.
2021, 39(7): 54-61,93.
doi: 10.13205/j.hjgc.202107006
Abstract:
During the application of porous membrane filtration to water treatment, particles in the feedwater can adsorb onto membrane surfaces and cause pore constriction or even blockage, resulting in severe membrane fouling. In this paper, studies pertaining to numerical models for the fouling process were systematically reviewed, with special focuses on the simulation of multilayer adsorption and the resultant pore constriction by waterborne particles. Generally, current models could be classified into three categories:macroscopic, mesoscopic and microscopic. Because membrane fouling involved the competitions between particle-fluid, particle-surface and particle-particle interactions, a suitable model should provide a detailed and simultaneous description of these interactions; this was currently difficult for realistic membrane filtration systems. Based upon these findings, this paper further outlined future prospect in developing and experimental validating numerical models for particulate membrane fouling. Advances in this field would better instruct water treatment plants to control membrane fouling.
During the application of porous membrane filtration to water treatment, particles in the feedwater can adsorb onto membrane surfaces and cause pore constriction or even blockage, resulting in severe membrane fouling. In this paper, studies pertaining to numerical models for the fouling process were systematically reviewed, with special focuses on the simulation of multilayer adsorption and the resultant pore constriction by waterborne particles. Generally, current models could be classified into three categories:macroscopic, mesoscopic and microscopic. Because membrane fouling involved the competitions between particle-fluid, particle-surface and particle-particle interactions, a suitable model should provide a detailed and simultaneous description of these interactions; this was currently difficult for realistic membrane filtration systems. Based upon these findings, this paper further outlined future prospect in developing and experimental validating numerical models for particulate membrane fouling. Advances in this field would better instruct water treatment plants to control membrane fouling.
2021, 39(7): 62-72.
doi: 10.13205/j.hjgc.202107007
Abstract:
The relevant studies on microbial community structure and EPS on RO membrane surface were reviewed. Meantime, the research of monitoring techniques and control methods of biofouling of RO membrane were summarized. In general, the relative abundances of Proteobacteria(α-,β-,γ-Proteobacteria), Bacteroidetes and Planctomycetes are higher than other phyla on RO membrane. The genera of Sphingomonas and Pseudomonas which produce more EPS play key roles in biofouling of RO membrane. Polysaccharides are more likely to adhere to the RO membrane. Macromolecular components of EPS have a higher fouling potential. TEP can accelerate the biofouling. The determination of organic and microbial parameters in the influent can reflect fouling potential of influent. The monitoring of membrane modules can reflect biofouling condition in time. Pretreatment and membrane cleaning have been used to alleviate biofouling, while surface modification and biological treatment provide new ways for biofouling control. Based on the research status, the future research perspectives regarding biofouling control are proposed, including enhancing the evaluation indexes system of biofouling potential, and the control of the dominant microbial species and EPS components, paying more attention to the engineering feasibility of anti-fouling membranes.
The relevant studies on microbial community structure and EPS on RO membrane surface were reviewed. Meantime, the research of monitoring techniques and control methods of biofouling of RO membrane were summarized. In general, the relative abundances of Proteobacteria(α-,β-,γ-Proteobacteria), Bacteroidetes and Planctomycetes are higher than other phyla on RO membrane. The genera of Sphingomonas and Pseudomonas which produce more EPS play key roles in biofouling of RO membrane. Polysaccharides are more likely to adhere to the RO membrane. Macromolecular components of EPS have a higher fouling potential. TEP can accelerate the biofouling. The determination of organic and microbial parameters in the influent can reflect fouling potential of influent. The monitoring of membrane modules can reflect biofouling condition in time. Pretreatment and membrane cleaning have been used to alleviate biofouling, while surface modification and biological treatment provide new ways for biofouling control. Based on the research status, the future research perspectives regarding biofouling control are proposed, including enhancing the evaluation indexes system of biofouling potential, and the control of the dominant microbial species and EPS components, paying more attention to the engineering feasibility of anti-fouling membranes.
2021, 39(7): 73-79.
doi: 10.13205/j.hjgc.202107008
Abstract:
Daqing Oilfield Xishuiyuan Water Plant took groundwater as the main water source, used conventional-ozone/activated carbon-ultrafiltration(UF) membrane treatment technology, and had been in operation for 5 years from its commissioning in 2014 to the end of 2019. The turbidity of the effluent from the water plant, organic matter(CODMn) and total number of colonies reached the standard stably. However, ultrafiltration membrane fouling led to changes in membrane performance. In order to explore the evolution of ultrafiltration membrane water treatment and membrane performance during the five years operation, the water quality of membrane effluent, membrane flux, transmembrane pressure and membrane fouling layer were analyzed. The results showed that the removal rate of turbidity and microorganism maintained above 90%, while the average removal rate of organic matter was only 9%. The specific flux of the ultrafiltration membrane decreased by 2.1%~4.6% per year. Clean in place(CIP) in the flux and specific flux recovery rate of the ultrafiltration membrane were maintained in the range of 73%~91% and 85%~92%, respectively. The analysis results of the fouling layer showed that the organic pollutants of the ultrafiltration membrane were mainly humic acid and protein; the inorganic pollutants were manganese, calcium, iron, silicon and aluminium. Complex pollutants formed by high-valent metal elements and organic matter played a dominant role in the pollution layer; at the same time, inorganic salt scales with silicon and calcium shouldn't be ignored.
Daqing Oilfield Xishuiyuan Water Plant took groundwater as the main water source, used conventional-ozone/activated carbon-ultrafiltration(UF) membrane treatment technology, and had been in operation for 5 years from its commissioning in 2014 to the end of 2019. The turbidity of the effluent from the water plant, organic matter(CODMn) and total number of colonies reached the standard stably. However, ultrafiltration membrane fouling led to changes in membrane performance. In order to explore the evolution of ultrafiltration membrane water treatment and membrane performance during the five years operation, the water quality of membrane effluent, membrane flux, transmembrane pressure and membrane fouling layer were analyzed. The results showed that the removal rate of turbidity and microorganism maintained above 90%, while the average removal rate of organic matter was only 9%. The specific flux of the ultrafiltration membrane decreased by 2.1%~4.6% per year. Clean in place(CIP) in the flux and specific flux recovery rate of the ultrafiltration membrane were maintained in the range of 73%~91% and 85%~92%, respectively. The analysis results of the fouling layer showed that the organic pollutants of the ultrafiltration membrane were mainly humic acid and protein; the inorganic pollutants were manganese, calcium, iron, silicon and aluminium. Complex pollutants formed by high-valent metal elements and organic matter played a dominant role in the pollution layer; at the same time, inorganic salt scales with silicon and calcium shouldn't be ignored.
2021, 39(7): 80-87,12.
doi: 10.13205/j.hjgc.202107009
Abstract:
The combined processes based on ceramic membrane were studied including coagulation, ozonation, ceramic membrane ultrafiltration and activated carbon filtration, for sludge water reuse in a drinking water treatment plant(WTP) in South China. A pilot system with a capacity of 10 m3/d was set up. Under membrane flux of 100 L/(m2·h) and transmembrane pressure TMP of 30 kPa, the removal efficiencies of the pilot-scale test for turbidity, color, CODMn, ammonia, geosmin(GSM), dimethyl trisulfide(DMTS), 2-methylisocamphenol(2-MIB), pharmaceuticals and personal care products(PPCPs) and endocrine disruptors(EDCs) were evaluated. The results showed that the quality of the treated sludge water was able to totally meet the requirement of China National Standards for Drinking Water Quality(GB 5749-2006). The average removal efficiencies of turbidity, color, CODMn, and ammonia were 99%, 100%, 75.9%, and 72.3%, respectively, and the average removal efficiencies of PPCPs, EDCs, DMTS and 2-MIB were 95.4%, 78.3%, 90.3% and 100%, respectively. The effluent quality of the pilot process was much better than that of the existing sludge water recovery processes in the WTP. Moreover, in situ ozonation in membrane tank could effectively alleviate the membrane fouling. The findings proved that the combined processes of ozonation/ceramic membrane filtration and activated carbon filtration was technically stable and feasible for the reuse of sludge water of water treatment plant.
The combined processes based on ceramic membrane were studied including coagulation, ozonation, ceramic membrane ultrafiltration and activated carbon filtration, for sludge water reuse in a drinking water treatment plant(WTP) in South China. A pilot system with a capacity of 10 m3/d was set up. Under membrane flux of 100 L/(m2·h) and transmembrane pressure TMP of 30 kPa, the removal efficiencies of the pilot-scale test for turbidity, color, CODMn, ammonia, geosmin(GSM), dimethyl trisulfide(DMTS), 2-methylisocamphenol(2-MIB), pharmaceuticals and personal care products(PPCPs) and endocrine disruptors(EDCs) were evaluated. The results showed that the quality of the treated sludge water was able to totally meet the requirement of China National Standards for Drinking Water Quality(GB 5749-2006). The average removal efficiencies of turbidity, color, CODMn, and ammonia were 99%, 100%, 75.9%, and 72.3%, respectively, and the average removal efficiencies of PPCPs, EDCs, DMTS and 2-MIB were 95.4%, 78.3%, 90.3% and 100%, respectively. The effluent quality of the pilot process was much better than that of the existing sludge water recovery processes in the WTP. Moreover, in situ ozonation in membrane tank could effectively alleviate the membrane fouling. The findings proved that the combined processes of ozonation/ceramic membrane filtration and activated carbon filtration was technically stable and feasible for the reuse of sludge water of water treatment plant.
2021, 39(7): 88-93.
doi: 10.13205/j.hjgc.202107010
Abstract:
Seawater desalination, in rapid development, is an effective measure to alleviate the freshwater scarcity crisis in China. However, there is a significant concern about the water quality and cost of the desalination systems, but little attention has been paid to the quantitative evaluation of water resource efficiency. Based on the ISO water footprint principle, this work delineated the system boundary of sea water desalination, performed the inventory analysis of the production phase of seawater desalination systems, and proposed a method for water footprint quantification and evaluation of typical seawater desalination systems. Evaluation results revealed that the scarcity footprint of the multi-effect distillation(MED) technology was 3~4 times higher than that of the reverse osmosis(RO) technology, and the power consumption was the determining factor for the water footprint of all the technologies. The degradation water footprint of RO technology was much lower than that of MED. Overall, the RO technology showed more excellent water resource efficiency than the MED among the studied cases. This work revealed the consumption and pollution of water resources in seawater desalination production via the water footprint analysis. It may help develop the sea water desalination improve water resource efficiency, reduce energy consumption and eliminate water pollution, and provide support for scientific development and utilization of seawater.
Seawater desalination, in rapid development, is an effective measure to alleviate the freshwater scarcity crisis in China. However, there is a significant concern about the water quality and cost of the desalination systems, but little attention has been paid to the quantitative evaluation of water resource efficiency. Based on the ISO water footprint principle, this work delineated the system boundary of sea water desalination, performed the inventory analysis of the production phase of seawater desalination systems, and proposed a method for water footprint quantification and evaluation of typical seawater desalination systems. Evaluation results revealed that the scarcity footprint of the multi-effect distillation(MED) technology was 3~4 times higher than that of the reverse osmosis(RO) technology, and the power consumption was the determining factor for the water footprint of all the technologies. The degradation water footprint of RO technology was much lower than that of MED. Overall, the RO technology showed more excellent water resource efficiency than the MED among the studied cases. This work revealed the consumption and pollution of water resources in seawater desalination production via the water footprint analysis. It may help develop the sea water desalination improve water resource efficiency, reduce energy consumption and eliminate water pollution, and provide support for scientific development and utilization of seawater.
2021, 39(7): 94-100.
doi: 10.13205/j.hjgc.202107011
Abstract:
The operation performance and mass balance of a large pilot-scale anaerobic membrane bioreactor(AnMBR) in treating real municipal wastewater was investigated, by using a demonstration plant in Sendai, Japan, at a temperature of 25℃ under the control of an automatic system. This plant with 5.0 m3 effective volume was the largest one-stage submerged AnMBR that has ever applied to the treatment of municipal wastewater. During the long-term operation of 217 days, this AnMBR system realized a low hydraulic retention time(HRT) of 6 h, obtaining excellent effluent quality with the COD removal efficiency over 90% and BOD5 removal rate over 95%. Biogas was successfully recovered from municipal wastewater with a biogas production of 0.5 L/g removed COD and 0.09~0.10 L/L raw wastewater, and the methane content in the biogas was over 75%. The sludge yield of the AnMBR was approximately 0.19~0.26 g MLSS/g COD. The suspended solid(SS) contained in the municipal wastewater was completely removed by the AnMBR, while the SS conversion efficiency was 34%~43%. The COD and nitrogen mass balance were also identified based on the experimental results. Under the operation mode of 4 min for permeating and 1 min for relaxing with a biogas sparging flow rate of 0.9 m3/min, the hollow-fiber membrane module with a total area of 72 m2 was able to realize a max flux of 17.75 L/(m2·h), and the highest mean transmembrane pressure(TMP) was 23.5 kPa. An online backwash chemical cleaning system helped reduce the TMP timely. However, the TMP increased rapidly during the HRT of 6 h and a weekly online backwash was necessary. This is the first report of successful operation and detail performance of a large scale AnMBR applied in the treatment of real municipal wastewater at an HRT of 6 hours.
The operation performance and mass balance of a large pilot-scale anaerobic membrane bioreactor(AnMBR) in treating real municipal wastewater was investigated, by using a demonstration plant in Sendai, Japan, at a temperature of 25℃ under the control of an automatic system. This plant with 5.0 m3 effective volume was the largest one-stage submerged AnMBR that has ever applied to the treatment of municipal wastewater. During the long-term operation of 217 days, this AnMBR system realized a low hydraulic retention time(HRT) of 6 h, obtaining excellent effluent quality with the COD removal efficiency over 90% and BOD5 removal rate over 95%. Biogas was successfully recovered from municipal wastewater with a biogas production of 0.5 L/g removed COD and 0.09~0.10 L/L raw wastewater, and the methane content in the biogas was over 75%. The sludge yield of the AnMBR was approximately 0.19~0.26 g MLSS/g COD. The suspended solid(SS) contained in the municipal wastewater was completely removed by the AnMBR, while the SS conversion efficiency was 34%~43%. The COD and nitrogen mass balance were also identified based on the experimental results. Under the operation mode of 4 min for permeating and 1 min for relaxing with a biogas sparging flow rate of 0.9 m3/min, the hollow-fiber membrane module with a total area of 72 m2 was able to realize a max flux of 17.75 L/(m2·h), and the highest mean transmembrane pressure(TMP) was 23.5 kPa. An online backwash chemical cleaning system helped reduce the TMP timely. However, the TMP increased rapidly during the HRT of 6 h and a weekly online backwash was necessary. This is the first report of successful operation and detail performance of a large scale AnMBR applied in the treatment of real municipal wastewater at an HRT of 6 hours.
2021, 39(7): 101-107.
doi: 10.13205/j.hjgc.202107012
Abstract:
Anaerobic digestion is accomplished in converting organic wastes such as sewage sludge into biogas, achieving waste reduction and resource recovery at the same time. However, conventional anaerobic digestion has the disadvantages of long HRT, poor effluent quality, high sensitivity to reactor pH, temperature and environmental conditions, etc. In this study, a high-solid anaerobic membrane bioreactor(AnMBR) with an effective volume of 15 L was applied for anaerobic digestion of sewage sludge(mixture of primary sludge and excess sludge). AnMBR is able to retain suspend solid(SS) in the reactor through efficient membrane filtration, which enhances the stability of the reactor operation and promotes the decomposition of organic matter. The AnMBR reactor realized stable operation under the conditions of 35℃, HRT 15 d, and organic load of 4.66 g-COD/(L·d) through a 155 days long-term operation experiment. During the experiment period, AnMBR was operating smoothly, ammonia nitrogen concentration was below the thresholdand and there was no volatile fatty acid accumulation. The biogas yield was 0.48 L/g-VS, and the average constitute of methane was 63.32%. The COD concentration in permeate was 0.77 g/L, and COD removal rate was as high as 98%. According to mass balance calculation, 54.38% of the total COD from the substrate was converted into methane, and only 0.6% remained in the effluent. In addition, this study achieved a continuous and stable working mode of 4 minutes of filtration and 1 minute of relaxation with average membrane flux of 9.6 L/(m2·h) under the condition of sludge concentration 25 g/L in the reactor. The calculation results of total membrane resistance showed that the total resistance was 11.87×1012/m. Cake layer attached to the membrane surface and the organic layer that causes the membrane pores blocking were the main factors of membrane fouling. This study investigated the feasibility of utilizing high-solid anaerobic membrane bioreactor in waste reduction and energy recovery through the performance of methane production and membrane filtration.
Anaerobic digestion is accomplished in converting organic wastes such as sewage sludge into biogas, achieving waste reduction and resource recovery at the same time. However, conventional anaerobic digestion has the disadvantages of long HRT, poor effluent quality, high sensitivity to reactor pH, temperature and environmental conditions, etc. In this study, a high-solid anaerobic membrane bioreactor(AnMBR) with an effective volume of 15 L was applied for anaerobic digestion of sewage sludge(mixture of primary sludge and excess sludge). AnMBR is able to retain suspend solid(SS) in the reactor through efficient membrane filtration, which enhances the stability of the reactor operation and promotes the decomposition of organic matter. The AnMBR reactor realized stable operation under the conditions of 35℃, HRT 15 d, and organic load of 4.66 g-COD/(L·d) through a 155 days long-term operation experiment. During the experiment period, AnMBR was operating smoothly, ammonia nitrogen concentration was below the thresholdand and there was no volatile fatty acid accumulation. The biogas yield was 0.48 L/g-VS, and the average constitute of methane was 63.32%. The COD concentration in permeate was 0.77 g/L, and COD removal rate was as high as 98%. According to mass balance calculation, 54.38% of the total COD from the substrate was converted into methane, and only 0.6% remained in the effluent. In addition, this study achieved a continuous and stable working mode of 4 minutes of filtration and 1 minute of relaxation with average membrane flux of 9.6 L/(m2·h) under the condition of sludge concentration 25 g/L in the reactor. The calculation results of total membrane resistance showed that the total resistance was 11.87×1012/m. Cake layer attached to the membrane surface and the organic layer that causes the membrane pores blocking were the main factors of membrane fouling. This study investigated the feasibility of utilizing high-solid anaerobic membrane bioreactor in waste reduction and energy recovery through the performance of methane production and membrane filtration.
PERFORMANCE OF NITROGEN REMOVAL AND MICROBIAL INTERACTION IN A TWO-STAGE DYNAMIC MEMBRANE BIOREACTOR
2021, 39(7): 108-115.
doi: 10.13205/j.hjgc.202107013
Abstract:
Dynamic membrane(DM) requires a low transmembrane pressure, which plays a key role in suspended solid removal and energy saving during wastewater treatment. DM can also protect anaerobic ammonium-oxidizing bacteria(AMX) which is used to increase nitrogen removal efficiency in wastewater with low C/N ratio. DM separated heterotrophs and autotrophs in A/O reactor treating low C/N wastewater into anaerobic tank and aerobic tank, respectively. Ammonium-oxidizing bacteria(AOB) was enriched in suspended sludge, and anaerobic ammonium-oxidizing bacteria(AMX) was enriched in biofilms of the O tank. Removal efficiency of ammonium, total nitrogen, and COD were(91.2±7.5)%,(81.0±8.1)%, and(86.4±7.5)%, respectively, with an influent C/N value of 1.0. COD was mainly removed in the A tank and total nitrogen in the O tank. Gravity-driven dynamic membranes achieved satisfactory suspended solid removal with a concentration of(12.2±4.5) mg/L in the effluent. Functional bacteria were enriched in different parts of the reactor by using dynamic membranes and biofilms. Denitrifiers were mainly present in the anaerobic tank(relative abundance of ca. 30%). The AOB was mainly enrich in suspended sludge in aerobic tank sludge, with relative abundance of ca. 5%, and anammox bacteria were abundant in the biofilm of the O tank.Resultsfrom network analysis showed that positive interactions accounted for more than 70% of all interactions among microbes in each community, which ensured the performance of the reactor. In summary, the combination of PN/A, DM, and A/O process, which improved the synergy of different functional bacteria and ensured nitrogen removal in wastewater with low C/N ratio, was a promising method for wastewater treatment.
Dynamic membrane(DM) requires a low transmembrane pressure, which plays a key role in suspended solid removal and energy saving during wastewater treatment. DM can also protect anaerobic ammonium-oxidizing bacteria(AMX) which is used to increase nitrogen removal efficiency in wastewater with low C/N ratio. DM separated heterotrophs and autotrophs in A/O reactor treating low C/N wastewater into anaerobic tank and aerobic tank, respectively. Ammonium-oxidizing bacteria(AOB) was enriched in suspended sludge, and anaerobic ammonium-oxidizing bacteria(AMX) was enriched in biofilms of the O tank. Removal efficiency of ammonium, total nitrogen, and COD were(91.2±7.5)%,(81.0±8.1)%, and(86.4±7.5)%, respectively, with an influent C/N value of 1.0. COD was mainly removed in the A tank and total nitrogen in the O tank. Gravity-driven dynamic membranes achieved satisfactory suspended solid removal with a concentration of(12.2±4.5) mg/L in the effluent. Functional bacteria were enriched in different parts of the reactor by using dynamic membranes and biofilms. Denitrifiers were mainly present in the anaerobic tank(relative abundance of ca. 30%). The AOB was mainly enrich in suspended sludge in aerobic tank sludge, with relative abundance of ca. 5%, and anammox bacteria were abundant in the biofilm of the O tank.Resultsfrom network analysis showed that positive interactions accounted for more than 70% of all interactions among microbes in each community, which ensured the performance of the reactor. In summary, the combination of PN/A, DM, and A/O process, which improved the synergy of different functional bacteria and ensured nitrogen removal in wastewater with low C/N ratio, was a promising method for wastewater treatment.
2021, 39(7): 116-121,150.
doi: 10.13205/j.hjgc.202107014
Abstract:
Membrane fouling can be defined as a particle deposition process on the surface of membrane. In order to understand the particle migration and deposition process in the filter channel, a computational fluid dynamics(CFD) model coupled with particle force analysis was studied. By editing the user-defined function(UDF) of the force of the particles and combining with the discrete phase model(DPM) in CFD, the particle behaviors were simulated during ultrafiltration. The CFD simulation results were further verified by batch-scale experiments and the accuracy of CFD simulation of particle deposition was evidenced by in-situ Micro-PIV visualization.Resultsshowed that the particle deposition probability was positively related to the transmembrane pressure difference, and inversely related to the cross-flow velocity. The velocity field in the membrane cavity was recorded by the trajectory of the tracer particles. This CFD model visually and intuitively revealed the flow field of the membrane process and the movement of particles, and provided a scientific basis for understanding membrane fouling and optimizing membrane modules.
Membrane fouling can be defined as a particle deposition process on the surface of membrane. In order to understand the particle migration and deposition process in the filter channel, a computational fluid dynamics(CFD) model coupled with particle force analysis was studied. By editing the user-defined function(UDF) of the force of the particles and combining with the discrete phase model(DPM) in CFD, the particle behaviors were simulated during ultrafiltration. The CFD simulation results were further verified by batch-scale experiments and the accuracy of CFD simulation of particle deposition was evidenced by in-situ Micro-PIV visualization.Resultsshowed that the particle deposition probability was positively related to the transmembrane pressure difference, and inversely related to the cross-flow velocity. The velocity field in the membrane cavity was recorded by the trajectory of the tracer particles. This CFD model visually and intuitively revealed the flow field of the membrane process and the movement of particles, and provided a scientific basis for understanding membrane fouling and optimizing membrane modules.
2021, 39(7): 122-127.
doi: 10.13205/j.hjgc.202107015
Abstract:
Some low molecular weight organics, such as dimethylbenzylamine(DMBA), indoline and 6-methylquinoline are difficult to remove from shale gas flowback water(SGFW). The combined process of coagulation-ozonation/adsorption-UF-RO was used to treat the SGFW to explore organic and inorganic components' removal efficiency. The results showed that:the removal rates of ions by coagulation-ozone-UF-RO combination process were 96.7~99.86%, the removal rates of DOC and UV254 were 98.7% and 99.13%, and the removal rates of DMBA, indoline and 6-methylquinoline were 82.02%, 98.02% and 97.67%; the removal rates of ions by coagulation-adsorption-UF-RO combination process were 95.99~99.86%, and the removal rates of DOC and UV254 were 95.99%~99.86%, the removal rates of DMBA, indoline and 6-methylquinoline were 70.19%, 94.70% and 87.93%. Coagulation-ozonation/adsorption-UF-RO process could effectively remove ions, DOC and UV254 in the effluent, and has significant removal effect on DMBA, indoline and 6-methylquinoline. The combined process could effectively ensure the external reuse of SGFW.
Some low molecular weight organics, such as dimethylbenzylamine(DMBA), indoline and 6-methylquinoline are difficult to remove from shale gas flowback water(SGFW). The combined process of coagulation-ozonation/adsorption-UF-RO was used to treat the SGFW to explore organic and inorganic components' removal efficiency. The results showed that:the removal rates of ions by coagulation-ozone-UF-RO combination process were 96.7~99.86%, the removal rates of DOC and UV254 were 98.7% and 99.13%, and the removal rates of DMBA, indoline and 6-methylquinoline were 82.02%, 98.02% and 97.67%; the removal rates of ions by coagulation-adsorption-UF-RO combination process were 95.99~99.86%, and the removal rates of DOC and UV254 were 95.99%~99.86%, the removal rates of DMBA, indoline and 6-methylquinoline were 70.19%, 94.70% and 87.93%. Coagulation-ozonation/adsorption-UF-RO process could effectively remove ions, DOC and UV254 in the effluent, and has significant removal effect on DMBA, indoline and 6-methylquinoline. The combined process could effectively ensure the external reuse of SGFW.
2021, 39(7): 128-132,72.
doi: 10.13205/j.hjgc.202107016
Abstract:
The high concentration of hydrolyzed polyacrylamide(HPAM) in the produced water of polymer flooding in high calcium magnesium reservoir leads to the deterioration of the water quality of the conventional oil separation coagulation filtration/air flotation process and the blockage and fouling of filter materials. Therefore, it is urgent to develop the treatment technology. Ceramic membrane has attracted more and more attention in oil and gas field wastewater treatment because of its good effluent quality, anti-fouling performance, acid and alkali resistance and other advantages. Based on the problem of high HPAM concentration in the produced water of polymer flooding in high calcium magnesium reservoir, in order to improve the effluent quality and stable operation, this paper carried out the study on the effect of chemical flocculation+ceramic membrane and ozone oxidation+chemical flocculation+ceramic membrane pretreatment on the effluent quality and fouling of ceramic membrane. In this study, the feasibility of the combination of two pretreatments(coagulation, and ozone oxidation combined with coagulation) with ceramic was studied. Experimental results demonstrated that both the pretreatments could effectively alleviate the membrane fouling and enhance water quality of the ceramic membrane. The water quality of treated water by ozone oxidation, coagulation and ceramic membrane met the injection requirements(SYT 5329-2012)as follows:turbidity <0.2 NTU, oil content<10 mg/L, COD<2000 mg/L, mean particle size<0.8 μm. Membrane fouling caused by surface entrapment was proved to be obviously alleviated when artificial wastewater was pretreated by ozonation and chemical flocculation. This study provided technical support for the treatment of polymer flooding produced water and HPAM produced water in high calcium and magnesium reservoir.
The high concentration of hydrolyzed polyacrylamide(HPAM) in the produced water of polymer flooding in high calcium magnesium reservoir leads to the deterioration of the water quality of the conventional oil separation coagulation filtration/air flotation process and the blockage and fouling of filter materials. Therefore, it is urgent to develop the treatment technology. Ceramic membrane has attracted more and more attention in oil and gas field wastewater treatment because of its good effluent quality, anti-fouling performance, acid and alkali resistance and other advantages. Based on the problem of high HPAM concentration in the produced water of polymer flooding in high calcium magnesium reservoir, in order to improve the effluent quality and stable operation, this paper carried out the study on the effect of chemical flocculation+ceramic membrane and ozone oxidation+chemical flocculation+ceramic membrane pretreatment on the effluent quality and fouling of ceramic membrane. In this study, the feasibility of the combination of two pretreatments(coagulation, and ozone oxidation combined with coagulation) with ceramic was studied. Experimental results demonstrated that both the pretreatments could effectively alleviate the membrane fouling and enhance water quality of the ceramic membrane. The water quality of treated water by ozone oxidation, coagulation and ceramic membrane met the injection requirements(SYT 5329-2012)as follows:turbidity <0.2 NTU, oil content<10 mg/L, COD<2000 mg/L, mean particle size<0.8 μm. Membrane fouling caused by surface entrapment was proved to be obviously alleviated when artificial wastewater was pretreated by ozonation and chemical flocculation. This study provided technical support for the treatment of polymer flooding produced water and HPAM produced water in high calcium and magnesium reservoir.
2021, 39(7): 133-138.
doi: 10.13205/j.hjgc.202107017
Abstract:
Extractive membrane bioreactor(EMBR) is an effective method to treat the refractory phenol saline wastewater, which could separate the phenol saline wastewater into low concentration phenol wastewater. Aimed to solve the issue of low phenol transmembrane mass transfer rate of silicone rubber tube in EMBR, novel polydimethylsiloxane(PDMS) membrane was developed in this study using phase inversion method, which could simultaneously achieve high phenol transmembrane mass transfer and high NaCl rejection. Effects of flow rate, pH and temperature in wastewater and bioreactor on phenol separation and NaCl rejection were investigated to optimize the operation condition of EMBR. Effects of microorganisms on phenol degradation and transmembrane mass transfer were also investigated.Resultsshowed that the optimal conditions for wastewater and bioreactor were flow rates of 0.17 L/h and 0.17 L/h, pH values of 5.1 and 5.75, temperatures of 34℃ and 30℃, respectively. After addition of sludge, transmembrane phenol mass transfer coefficients of 4.0×10-7~4.3×10-7 m/s, phenol removal efficiencies around 100% and NaCl rejection efficiencies above 99.9% could be achieved in this EMBR. This study was beneficial in solving the key problems in application and popularization of EMBR, and was of great importance in the pollution treatment of water environment and security guarantee of water resource.
Extractive membrane bioreactor(EMBR) is an effective method to treat the refractory phenol saline wastewater, which could separate the phenol saline wastewater into low concentration phenol wastewater. Aimed to solve the issue of low phenol transmembrane mass transfer rate of silicone rubber tube in EMBR, novel polydimethylsiloxane(PDMS) membrane was developed in this study using phase inversion method, which could simultaneously achieve high phenol transmembrane mass transfer and high NaCl rejection. Effects of flow rate, pH and temperature in wastewater and bioreactor on phenol separation and NaCl rejection were investigated to optimize the operation condition of EMBR. Effects of microorganisms on phenol degradation and transmembrane mass transfer were also investigated.Resultsshowed that the optimal conditions for wastewater and bioreactor were flow rates of 0.17 L/h and 0.17 L/h, pH values of 5.1 and 5.75, temperatures of 34℃ and 30℃, respectively. After addition of sludge, transmembrane phenol mass transfer coefficients of 4.0×10-7~4.3×10-7 m/s, phenol removal efficiencies around 100% and NaCl rejection efficiencies above 99.9% could be achieved in this EMBR. This study was beneficial in solving the key problems in application and popularization of EMBR, and was of great importance in the pollution treatment of water environment and security guarantee of water resource.
2021, 39(7): 139-144.
doi: 10.13205/j.hjgc.202107018
Abstract:
Traditional membrane separation is unable to achieve simultaneous removal of multiple pollutants under low pressure. In this paper, the sequenced separation-adsorption dual-function ultrafiltration membrane(DFUM) was prepared by immobilizing ZIF-8 into the finger-like pores of the asymmetric ultrafiltration membrane for multiple pollutants simultaneous removal. Without changing the original membrane structure and retention performance of DFUM, the loading capacity of ZIF-8 nanoparticles could reach 2.87 mg/cm2. The decontamination performance results showed that the sequenced structure could simultaneously remove humic acid and Cu2+ with removal rate of 95.4% and 97%, at a pressure of 1.6 bar and a flux of 45 L/(m2·h) and protected the process of Cu2+ removal from the interference of the coexisted humic acid; compared with the method of surface deposition, the effective removal volume of Cu2+ could be increased by three times by the DFUM. This study provided a novel strategy for excellent removal of multiple pollutants in water.
Traditional membrane separation is unable to achieve simultaneous removal of multiple pollutants under low pressure. In this paper, the sequenced separation-adsorption dual-function ultrafiltration membrane(DFUM) was prepared by immobilizing ZIF-8 into the finger-like pores of the asymmetric ultrafiltration membrane for multiple pollutants simultaneous removal. Without changing the original membrane structure and retention performance of DFUM, the loading capacity of ZIF-8 nanoparticles could reach 2.87 mg/cm2. The decontamination performance results showed that the sequenced structure could simultaneously remove humic acid and Cu2+ with removal rate of 95.4% and 97%, at a pressure of 1.6 bar and a flux of 45 L/(m2·h) and protected the process of Cu2+ removal from the interference of the coexisted humic acid; compared with the method of surface deposition, the effective removal volume of Cu2+ could be increased by three times by the DFUM. This study provided a novel strategy for excellent removal of multiple pollutants in water.
2021, 39(7): 145-150.
doi: 10.13205/j.hjgc.202107019
Abstract:
The existence of a large number of polymers in polymer flooding oil production wastewater affects the properties of the sewage, and its pollution mechanism for ultrafiltration membranes is different from that of the general oil production wastewater. In this paper, the influence of polymer concentration on membrane flux in the process of simulating polymer-containing wastewater in ultrafiltration filtration was studied. The chemical cleaning scheme was optimized through chemical cleaning of the membrane fibers contaminated by the actual raw water and scanning electron microscope analysis of the contaminated membrane surface and section. On this basis, the preferred chemical cleaning scheme was used to clean the membrane modules in engineering applications. The research results showed that as the polymer concentration increased, the membrane flux attenuation gradually increased; the combination of sodium hydroxide and sodium dodecylbenzene sulfonate had the best cleaning effect on polymer pollution, which restored 75% of the initial flux; scanning electron microscopy showed that substances in the raw water would accumulate on the membrane surface to form a stable gel layer and cause irreversible pollution to the membrane.
The existence of a large number of polymers in polymer flooding oil production wastewater affects the properties of the sewage, and its pollution mechanism for ultrafiltration membranes is different from that of the general oil production wastewater. In this paper, the influence of polymer concentration on membrane flux in the process of simulating polymer-containing wastewater in ultrafiltration filtration was studied. The chemical cleaning scheme was optimized through chemical cleaning of the membrane fibers contaminated by the actual raw water and scanning electron microscope analysis of the contaminated membrane surface and section. On this basis, the preferred chemical cleaning scheme was used to clean the membrane modules in engineering applications. The research results showed that as the polymer concentration increased, the membrane flux attenuation gradually increased; the combination of sodium hydroxide and sodium dodecylbenzene sulfonate had the best cleaning effect on polymer pollution, which restored 75% of the initial flux; scanning electron microscopy showed that substances in the raw water would accumulate on the membrane surface to form a stable gel layer and cause irreversible pollution to the membrane.
2021, 39(7): 151-155.
doi: 10.13205/j.hjgc.202107020
Abstract:
The water supply scale of the Zhangjiagang Third Water Plant was 200000 m3/d, and its drinking water treatment process is sequentially combined by coagulation, sedimentation, filtration and chlorination disinfection. Based on the remarkable interception ability of nanofiltration membrane for monomolecular organic matters, micromolecular organic matters and saline ions including calcium ion, magnesium ion, sulfate ion, etc, a new water purification process combined by conventional technology, pressed-pot microfiltration and nanofiltrition was creatively applied in the large-scale engineering project of drinking water advanced treatment for the Zhangjiagang Third Water Plant, for the first time in China. The designed water production capacity of this project was 100000 t/d, and the project was aimed at upgrading the existing drinking water treatment technology. After the reformation, the nanofiltration system was predicted to perform over 90% removal rate for COD and TOC, 70%~80% removal rate for disinfection by-products, over 70% removal rate for pigments, 50%~70% removal rate for odorous substances, and 30%~40% rejection rate for salt. The recovery rate of the nanofiltration system was able to reach 90%, while the predicted energy consumption of pressed-pot microfiltration system and nanofiltration system was respectively 0.003, 0.197 kW·h/t, respectively. After accomplishing the project, Zhangjiagang Third Water Treatment Plant will be capable of supplying drinking water with higher quality, and possess higher resistance to water contamination emergencies.
The water supply scale of the Zhangjiagang Third Water Plant was 200000 m3/d, and its drinking water treatment process is sequentially combined by coagulation, sedimentation, filtration and chlorination disinfection. Based on the remarkable interception ability of nanofiltration membrane for monomolecular organic matters, micromolecular organic matters and saline ions including calcium ion, magnesium ion, sulfate ion, etc, a new water purification process combined by conventional technology, pressed-pot microfiltration and nanofiltrition was creatively applied in the large-scale engineering project of drinking water advanced treatment for the Zhangjiagang Third Water Plant, for the first time in China. The designed water production capacity of this project was 100000 t/d, and the project was aimed at upgrading the existing drinking water treatment technology. After the reformation, the nanofiltration system was predicted to perform over 90% removal rate for COD and TOC, 70%~80% removal rate for disinfection by-products, over 70% removal rate for pigments, 50%~70% removal rate for odorous substances, and 30%~40% rejection rate for salt. The recovery rate of the nanofiltration system was able to reach 90%, while the predicted energy consumption of pressed-pot microfiltration system and nanofiltration system was respectively 0.003, 0.197 kW·h/t, respectively. After accomplishing the project, Zhangjiagang Third Water Treatment Plant will be capable of supplying drinking water with higher quality, and possess higher resistance to water contamination emergencies.
2021, 39(7): 156-161,100.
doi: 10.13205/j.hjgc.202107021
Abstract:
Membrane bioreactor has become one of the important water reclamation equipment. It is advantageous in enhanced biochemical treatment performance, steady effluent quality and quantity, etc., but is impeded for further application by high investment and operational costs. This study developed a novel arrayed flat sheet membrane for membrane bioreactor, which had a critical flux at 114~120 L/(m2·h) with better uniformity than the hollow fiber membrane. The application in municipal wastewater treatment plants revealed that the novel arrayed flat sheet membrane had significantly lower and slower-growing transmembrane pressure than the hollow fiber membrane with flux at 16~25 L/(m2·h) and regular high-intensity aeration. The effluent quality met the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002,I-A). Thus, the novel arrayed flat sheet membrane could guarantee the effluent quality and reduce the operational cost of membrane bioreactor.
Membrane bioreactor has become one of the important water reclamation equipment. It is advantageous in enhanced biochemical treatment performance, steady effluent quality and quantity, etc., but is impeded for further application by high investment and operational costs. This study developed a novel arrayed flat sheet membrane for membrane bioreactor, which had a critical flux at 114~120 L/(m2·h) with better uniformity than the hollow fiber membrane. The application in municipal wastewater treatment plants revealed that the novel arrayed flat sheet membrane had significantly lower and slower-growing transmembrane pressure than the hollow fiber membrane with flux at 16~25 L/(m2·h) and regular high-intensity aeration. The effluent quality met the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002,I-A). Thus, the novel arrayed flat sheet membrane could guarantee the effluent quality and reduce the operational cost of membrane bioreactor.
2021, 39(7): 162-166,144.
doi: 10.13205/j.hjgc.202107022
Abstract:
Membrane bioreactor(MBR) technology has been widely used in water treatment industry because of its advantages like small footprint, good effluent quality, large biomass and low sludge yield. Since 2010, the number of MBR water plants has been increasing rapidly in China. Nowadays, the performance of MBR products in the early water plants has deteriorated seriously or reached the service life, cannot continue to meet the requirements of the treatment water quantity, and there is a need to add new membrane cassettes and replace membrane cassettes successively. This paper took a new assembly water plant project as an example, evaluated the operation of the original and new membrane cassettes after the addition of the membrane cassettes, and analysed the influence of the cassettes' difference on the system operation. The results showed that the new membrane cassettes ran stably for 160 days under the conditions of flux of 20.8 L/(m2·h), aeration intensity of 70 Nm3/(m2·h) and air-water ratio of 6, and the specific flux attenuation reached about 30%. At the same time, the scavenging energy consumption of the new assembly was lower than that of the original assembly. In addition, on the premise that the return flow cannot be improved, the high-throughput operation of the new packer may lead to uneven distribution of sludge concentration in the corridor and significant sludge concentration at the return end. Influenced by the pressure loss of the production pipe, the difference of the water production of each unit in the corridor resulted in different pollution degree of each unit.
Membrane bioreactor(MBR) technology has been widely used in water treatment industry because of its advantages like small footprint, good effluent quality, large biomass and low sludge yield. Since 2010, the number of MBR water plants has been increasing rapidly in China. Nowadays, the performance of MBR products in the early water plants has deteriorated seriously or reached the service life, cannot continue to meet the requirements of the treatment water quantity, and there is a need to add new membrane cassettes and replace membrane cassettes successively. This paper took a new assembly water plant project as an example, evaluated the operation of the original and new membrane cassettes after the addition of the membrane cassettes, and analysed the influence of the cassettes' difference on the system operation. The results showed that the new membrane cassettes ran stably for 160 days under the conditions of flux of 20.8 L/(m2·h), aeration intensity of 70 Nm3/(m2·h) and air-water ratio of 6, and the specific flux attenuation reached about 30%. At the same time, the scavenging energy consumption of the new assembly was lower than that of the original assembly. In addition, on the premise that the return flow cannot be improved, the high-throughput operation of the new packer may lead to uneven distribution of sludge concentration in the corridor and significant sludge concentration at the return end. Influenced by the pressure loss of the production pipe, the difference of the water production of each unit in the corridor resulted in different pollution degree of each unit.
2021, 39(7): 167-172.
doi: 10.13205/j.hjgc.202107023
Abstract:
MBR had become one of the most effective technologies in the field of municipal wastewater advanced treatment due to its obvious advantages, but its high operating cost limited its promotion and application. Taking a large MBR sewage treatment project of a reclaimed water plant in North China for example, membrane pollution and operation energy consumption were explored by adopting new membrane device and reasonable process design. The following conclusions were drawn by analyzing the actual operation data as follows:1) although the concentration of the influent pollutants fluctuated greatly, the effluent quality was stable and water quality indices were superior than the class B requirements specified in Water Pollutants for Municipal Wastewater Treatment Plants(DB 11/890-2012); 2) the membrane products in applied in the MBR system was PVDF material and prepared by TIPS method. The membrane featured high strength and high filling density, reaching 895 m2/m3; 3) advanced pre-treatment system and high intensity pulse aeration system were adopted in the MBR to effectively reduce the membrane fouling, and then the aeration cost was reduced by about 25%.
MBR had become one of the most effective technologies in the field of municipal wastewater advanced treatment due to its obvious advantages, but its high operating cost limited its promotion and application. Taking a large MBR sewage treatment project of a reclaimed water plant in North China for example, membrane pollution and operation energy consumption were explored by adopting new membrane device and reasonable process design. The following conclusions were drawn by analyzing the actual operation data as follows:1) although the concentration of the influent pollutants fluctuated greatly, the effluent quality was stable and water quality indices were superior than the class B requirements specified in Water Pollutants for Municipal Wastewater Treatment Plants(DB 11/890-2012); 2) the membrane products in applied in the MBR system was PVDF material and prepared by TIPS method. The membrane featured high strength and high filling density, reaching 895 m2/m3; 3) advanced pre-treatment system and high intensity pulse aeration system were adopted in the MBR to effectively reduce the membrane fouling, and then the aeration cost was reduced by about 25%.
2021, 39(7): 173-178.
doi: 10.13205/j.hjgc.202107024
Abstract:
A high separation nanofiltration system consisting of 3 sub-nanofiltration systems was proposed and its effect in zero discharge project of high salt wastewater from coal chemical industry was analyzed.Resultsshowed that the average rejection rates of SO42- and Cl- were 99.7% and-13.7% respectively, and the average water recovery rate was 81.9%, which indicated a good separation effect of monovalent and divalent salts. The fluctuation of water recovery rates and operating pressures of nanofiltration system and its subsystems in continuous operation were small, and the system operation stability was high. The average rejection rates of COD, Ca2+ and Mg2+ were 47.6%, 76.9% and 86.0% respectively, while the cleaning frequencies were 2.1, 0 and 1.0 times per month respectively, which indicated that the system had a high anti-fouling performance. The plant demonstrated that the high separation nanofiltration system had a promising prospect in the field of zero discharge of high salt wastewater.
A high separation nanofiltration system consisting of 3 sub-nanofiltration systems was proposed and its effect in zero discharge project of high salt wastewater from coal chemical industry was analyzed.Resultsshowed that the average rejection rates of SO42- and Cl- were 99.7% and-13.7% respectively, and the average water recovery rate was 81.9%, which indicated a good separation effect of monovalent and divalent salts. The fluctuation of water recovery rates and operating pressures of nanofiltration system and its subsystems in continuous operation were small, and the system operation stability was high. The average rejection rates of COD, Ca2+ and Mg2+ were 47.6%, 76.9% and 86.0% respectively, while the cleaning frequencies were 2.1, 0 and 1.0 times per month respectively, which indicated that the system had a high anti-fouling performance. The plant demonstrated that the high separation nanofiltration system had a promising prospect in the field of zero discharge of high salt wastewater.
2021, 39(7): 179-184.
doi: 10.13205/j.hjgc.202107025
Abstract:
Driven by the strategy and policy of national sewage and wastewater resource, zero liquid discharge of industrial wastewater has become an inevitable trend. As a heavy industry, the circulating cooling wastewater from cement plants is characterized by high salt content, high condensate ratio and high concentration of calcium and magnesium ions. Scientific and effective desalination treatment must be carried out before discharge and reuse to reduce the environmental pollution. The traditional treatment process has many deficiencies, such as large dosage, unstable operation, and large amount of residual chemical sludge which is easy to cause the secondary pollution. In this study, the technical idea of advanced treatment of wastewater by coagulation sedimentation+reverse osmosis+electrodialysis process was proposed. The function and characteristics of electrodialysis unit in the treatment of high salt wastewater were discussed, and its operation effect was investigated. Through the operation of a cement plant in Shaanxi province for more than 2 months, the results showed that the desalination rate of electrodialysis system was 24.7%, the concentration ratio of electrodialysis system was 14.6 times, the average conductivity and water yield of the concentrate liquid were 147.7 mS/cm and 0.07 m3/h, respectively.
Driven by the strategy and policy of national sewage and wastewater resource, zero liquid discharge of industrial wastewater has become an inevitable trend. As a heavy industry, the circulating cooling wastewater from cement plants is characterized by high salt content, high condensate ratio and high concentration of calcium and magnesium ions. Scientific and effective desalination treatment must be carried out before discharge and reuse to reduce the environmental pollution. The traditional treatment process has many deficiencies, such as large dosage, unstable operation, and large amount of residual chemical sludge which is easy to cause the secondary pollution. In this study, the technical idea of advanced treatment of wastewater by coagulation sedimentation+reverse osmosis+electrodialysis process was proposed. The function and characteristics of electrodialysis unit in the treatment of high salt wastewater were discussed, and its operation effect was investigated. Through the operation of a cement plant in Shaanxi province for more than 2 months, the results showed that the desalination rate of electrodialysis system was 24.7%, the concentration ratio of electrodialysis system was 14.6 times, the average conductivity and water yield of the concentrate liquid were 147.7 mS/cm and 0.07 m3/h, respectively.
2021, 39(7): 185-191.
doi: 10.13205/j.hjgc.202107026
Abstract:
In order to share the successful experience of a 17500 m3/d papermaking wastewater zero discharge project in a domestic industrial park in China, this paper focused on design parameters of the combined process, pretreatment+multi-stage membrane concentration+evaporative crystallization+membrane electrolysis, and analyzed the operation data of some process units. The operation data showed that the removal rate of residual COD in the secondary effluent of papermaking wastewater by ozone activated carbon biofilter was more than 50%, the removal rate of hardness index in the first RO concentration by mechanical accelerated clarifier was 70%, the effluent hardness of ion exchanger was stable at 0~4 mg/L, and the reconcentration ratio of chloride ion by sodium chloride concentration RO unit was about 3 times. Finally, the paper introduced the engineering experience of membrane concentration and evaporation crystallization system transformation, and illustrated that the perfect process flow and technical guarantee measures were the key to the success of this zero discharge project of industrial wastewater from the perspective of technical summary.
In order to share the successful experience of a 17500 m3/d papermaking wastewater zero discharge project in a domestic industrial park in China, this paper focused on design parameters of the combined process, pretreatment+multi-stage membrane concentration+evaporative crystallization+membrane electrolysis, and analyzed the operation data of some process units. The operation data showed that the removal rate of residual COD in the secondary effluent of papermaking wastewater by ozone activated carbon biofilter was more than 50%, the removal rate of hardness index in the first RO concentration by mechanical accelerated clarifier was 70%, the effluent hardness of ion exchanger was stable at 0~4 mg/L, and the reconcentration ratio of chloride ion by sodium chloride concentration RO unit was about 3 times. Finally, the paper introduced the engineering experience of membrane concentration and evaporation crystallization system transformation, and illustrated that the perfect process flow and technical guarantee measures were the key to the success of this zero discharge project of industrial wastewater from the perspective of technical summary.
2021, 39(7): 192-198.
doi: 10.13205/j.hjgc.202107027
Abstract:
Owing to the high chemical oxygen demand(COD), organic nitrogen content, and toxicity, the treatment effectiveness of conventional process for pesticide chemical wastewater is relativity low. Treatment of pesticide wastewater becomes a concerned issue in water treatment processes. Aiming at the problems that the condensate wastewater generated by the pesticide wastewater was not properly treated by conventional biological treatment processes, this project proposed a reconstruction scheme by adopting advanced biological treatment process using engineering bacteria synergism and dual-membrane process including ultrafiltration(UF) membrane and reverse osmosis(RO) membrane. After the reconstruction, stable wastewater treatment performance with improved rejection of the COD and TN(with the rejection rate of 85% and 67%, respectively) was observed in the system, and the start-up time of the biochemical system was also shortened. Besides, the dual-membrane process guaranteed the quality of the effluent with COD<500 mg/L, TN<70 mg/L, and NH3-N<45 mg/L, reaching the standard requirements of the downstream sewage treatment plant. In addition, the total operation cost of the project was 2.77 RMB/ton. The application of the advanced biological treatment process using engineering bacteria synergism, combined with the dual-membrane process guaranteed the efficient treatment of the condensate wastewater from the pesticide chemical plant.
Owing to the high chemical oxygen demand(COD), organic nitrogen content, and toxicity, the treatment effectiveness of conventional process for pesticide chemical wastewater is relativity low. Treatment of pesticide wastewater becomes a concerned issue in water treatment processes. Aiming at the problems that the condensate wastewater generated by the pesticide wastewater was not properly treated by conventional biological treatment processes, this project proposed a reconstruction scheme by adopting advanced biological treatment process using engineering bacteria synergism and dual-membrane process including ultrafiltration(UF) membrane and reverse osmosis(RO) membrane. After the reconstruction, stable wastewater treatment performance with improved rejection of the COD and TN(with the rejection rate of 85% and 67%, respectively) was observed in the system, and the start-up time of the biochemical system was also shortened. Besides, the dual-membrane process guaranteed the quality of the effluent with COD<500 mg/L, TN<70 mg/L, and NH3-N<45 mg/L, reaching the standard requirements of the downstream sewage treatment plant. In addition, the total operation cost of the project was 2.77 RMB/ton. The application of the advanced biological treatment process using engineering bacteria synergism, combined with the dual-membrane process guaranteed the efficient treatment of the condensate wastewater from the pesticide chemical plant.
