This review provides an insight and up-to-date information on the application of Moringa oleifera seeds, the short falls of existing technologies as a coagulant and disinfectant in domestic water treatment. While the ...This review provides an insight and up-to-date information on the application of Moringa oleifera seeds, the short falls of existing technologies as a coagulant and disinfectant in domestic water treatment. While the coagulant properties are well reported, the disinfectant properties are not well studied. Literatures on low cost alternative technologies such as the application of hiocoagulants and slow sand filters are extensively reported. However, there is limited work addressing the limitations of these technologies that have restricted its widespread use to solve the global soaring water crises. Slow sand filters have a very slow filtration rate that depends on the biofilm layer which takes about 17 days to form. Moringa oleifera treated water cannot last more than 48 hours without bacteria regrowth. Investigation of the best method of isolating coagulant component continues with differing opinions over the nature of its coagulant ingredient not resolved in ongoing literature. An attempt was made in this paper to highlight the advantages of a Moringa disinfectant sand filter hybrid system that can purify water. Microbiological advantages of this system in providing a 100% removal of pathogens, and engineering considerations such as water treatment within an hour residence time, faster flow rates, less clogging and backwashing could be some of the advantages ofa Moringa sand filter system. The need to focus on integrating Moringa and sand filter systems for more practical applications is recommended.展开更多
In order to protect quality of Baiyangdian surface water and Gaoyang groundwater,the project is applied to process printing and dyeing wastewater that contains complicated compositions,high concentrations of organics ...In order to protect quality of Baiyangdian surface water and Gaoyang groundwater,the project is applied to process printing and dyeing wastewater that contains complicated compositions,high concentrations of organics and SS,and lots of pollutants difficult to degrade by microorganism. The process and operating parameters of project are optimized and debugged,and its economic and environmental benefits are analyzed.The results show that the process of coagulation sedimentation-hydrolytic acidification with aeration tank-biological aerated filter-active sand filter is applied in Gaoyang Sewage Treatment Plant. The design scale of sewage treatment plant is 120000 m^3/d. The influent is as following: COD is 669mg/L; SS is 424mg/L; NH_3-N is 8.83mg/L; TP is 6.03mg/L. After the process,the best removal rates of COD,SS,NH_3-N and TP are 93. 5%,98. 8%,97. 1% and 96. 2%,respectively. The various indexes of effluent water complied with standard A of the first order in Pollutants Emission Standard of Urban Wastewater Treatment Plant( GB 18918-2002). The processing cost is only 0. 807 yuan/m^3. As a result,the project construction and operation not only improve the environment,but also promote regional economic development. Process design and operating parameters provide an important reference value for the printing and dyeing wastewater treatment industry.展开更多
Rain water is an important source to feed the groundwater aquifer, whether directly or by harvesting and recharging. The importance of purification is for reducing the risk of pollutants from recharging runoff rainwat...Rain water is an important source to feed the groundwater aquifer, whether directly or by harvesting and recharging. The importance of purification is for reducing the risk of pollutants from recharging runoff rainwater. The use of sand filter as a technique considered not expensive and commonly used for removing contaminants from water and wastewater treatment industries. The methodology used laboratory testing, by designing and constructing pilot plant to experiment the sand filter for purification, and made simulation for the infiltration of storm water through sand filter of 2 meters depth, in order to find the relationship between the depth on one hand, and the removal of suspended solids and fecal coliforms bacteria on the other hand, to know the effective depth that gets the purification. The research results during three days of infiltration show that the sand filter can remove fecal coliforms bacteria at a depth of 150 cm, and provide purified water with a concentration of suspended solids less than 20 mg/liter at a depth of 75 cm.展开更多
In?ltration percolation is a rustic and extensive purifying technique which is capable of completely oxidizing and decontaminating wastewater. The object of the present study is to validate on a real scale the finding...In?ltration percolation is a rustic and extensive purifying technique which is capable of completely oxidizing and decontaminating wastewater. The object of the present study is to validate on a real scale the findings gotten in pilot laboratory. It is notably to confirming the purification performances and decontamination of secondary effluent by sand filter drained under an intense wild plant. For this, a basin of 100 m2 of infiltration surface equipped with two wells of sampling in the center and in the periphery, has been constructed in irrigated perimeter of Dissa in Gabes (south east of Tunisia). Our results show that essential of the COD is eliminated in first 50 centimeters in sand filter and the presence of wild plant on the surface of infiltration damaged quality of filtered water. The follow-up of the organic nitrogen and ammonium show the good performances of process in elimination of nitrogenous pollution. The rate of exhaustion is about 100% and this since first 50 centimeters of filtration. The sand filter retains the different shapes of the phosphor by adsorption and precipitation in the superficial horizon. The elimination of the bacterial pollution is high, it varying from 0.1 to 2.5 Ulog. The bacterial purification remained low after 50 cm filtration. Indeed, with 50 cm depth, the quality of the filtrate is slightly better than the influent with still tendency to higher removal in the center than in periphery of the basin.展开更多
A novel integrated water treatment facility, inner-recycling continuous sand filter, is discussed. The theory of micro-flocculation is applied in the sand-washing circulation system with continuous filtration and back...A novel integrated water treatment facility, inner-recycling continuous sand filter, is discussed. The theory of micro-flocculation is applied in the sand-washing circulation system with continuous filtration and backwashing. The design and operation parameters, which affect the performance of the filter, are discussed. The key design parameters are provided as follows: diameter of filter material is 0.7 to 1.0 mm, depth of filter bed is 0.6 m, filtration velocity is less than 12 m/h, ratio of gas to water is 9:11 and sand recycling rate is 2 to 4 mm/min.展开更多
The effects of uncoated and Fe-coated biochars(BC)on the removal of bacteria,microspheres,and dissolved reactive phosphorus(DRP)in sand filters were compared.Filters were packed with 1.2 or 2.0-mm sand mixed with 30%(...The effects of uncoated and Fe-coated biochars(BC)on the removal of bacteria,microspheres,and dissolved reactive phosphorus(DRP)in sand filters were compared.Filters were packed with 1.2 or 2.0-mm sand mixed with 30%(vol/vol)uncoated BC,Fe-coated BC,or a control without BC.Removal of E.coli,Salmonella,and Enterococci increased from 23,42,and 25%in the unamended 1.2-mm sand to 48,80,and 75%in the uncoated BC treatment,though only the increase for Enterococci was significant(p<0.05).For the Fe-coated BC,removal efficiencies were 89,93,and 94%,respectively,which were all significantly(p<0.05)greater than the unamended sand but only the removal of E.coli was significantly greater than the uncoated BC sand filter.For the 2.0-mm sands,the only significant increase in removal following BC addition was observed for Salmonella.Trends in microsphere removal were generally consistent with bacteria.Removal of DRP in the unamended and uncoated BC filters was 33 and 13%(p>0.05),respectively,whereas removal in the Fe-coated BC filters was 98%(p<0.05).Results from batch sorption experiments indicate that both BCs similarly increased bacterial sorption to sand.In contrast,DRP sorption to the unamended and uncoated BC-amended sands were similar(p>0.05)with DRP sorption to the Fe-coated BC-amended sand being significantly greater(p<0.05).Results indicate that Fe-coated BC is more effective at retaining DRP than bacteria and microspheres in sand filters.展开更多
The addition of biochar to sand columns can enhance the retention of bacteria and thus may provide a management strategy for removing bacteria from tile-drainage waters.In this study,the role of sand size as a factor ...The addition of biochar to sand columns can enhance the retention of bacteria and thus may provide a management strategy for removing bacteria from tile-drainage waters.In this study,the role of sand size as a factor in controlling microbial reten-tion in biochar-amended sand columns was investigated.Laboratory column experiments were conducted to quantify the removal of two bacterial isolates(E.coli and Salmonella)and polystyrene microspheres in 10-cm-long columns packed with clean sand of three different sizes(0.25,0.71,and 1.19 mm)at four biochar concentrations(0%,5%,10%,and 15%).Sorption studies were also performed to help identify the relative roles of sorption and physical straining on the removal of bacteria and microspheres within the columns.For the large sand,the log10 removal values(LRV)for E.coli increased from 0.22 to 0.49 for the 0%and 15%biochar concentrations,respectively,while LRV for Salmonella increased from 0.19 to 0.68.For the small sand,increasing biochar concentration from 0%to 15%increased LRV from 0.11 to 1.9 for E.coli and from 0.20 to 4.6 for Salmonella.In comparison,LRV for microspheres in the 15%biochar columns was only minimally higher than the unamended columns for all three sand sizes.Results from the sorption studies show that high sorption coefficients generally correlated with high LRV indicating that sorption rather than physical straining was the primary mechanism of retention in the columns.Results from this study further our understanding of bacterial retention in biochar-amended porous media.展开更多
Backwashing is crucial for preventing clogging of sand filters.However,few studies have investigated the effect of backwashing on micropollutant removal and the dynamic changes in the microbial community in sand filte...Backwashing is crucial for preventing clogging of sand filters.However,few studies have investigated the effect of backwashing on micropollutant removal and the dynamic changes in the microbial community in sand filters.Here,we used a series of manganese and quartz sand filters under empty bed contact times(EBCTs)of 2 h and 4 h to explore variations in micropollutant degradation and temporal dynamics of the microbial community after backwashing.The results showed that the removal efficiencies of caffeine,sulfamethoxazole,sulfadiazine,trimethoprim,atrazine,and active biomass recovered within 2 d after backwashing in both types of sand filters at 2-h EBCT,but the recovery of sulfadiazine and trimethoprim was not observed at 4-h EBCT.Moreover,the removal efficiency of atenolol increased after backwashing in the manganese sand filters,whereas maintained almost complete removal efficiency in the quartz sand filters at both EBCTs.Pearson correlation analysis indicated that microbial community composition gradually recovered to the pre-backwashing level(R increased from 0.53 to 0.97)at 2-h EBCT,but shifted at 4-h EBCT(R<0.25)after backwashing.Furthermore,the compositions of the recovered,depleted,and improved groups of microbes were distinguished by applying hierarchical clustering to the differentially abundant amplicon sequence variants.The cumulative relative abundance of recovered microbes at 2-h EBCT was 82.76%±0.43%and 46.82%±4.34%in the manganese and quartz sand filters,respectively.In contrast,at 4-h EBCT,the recovered microbes dropped to 15.55%–25.69%in both types of sand filters.展开更多
Modeling of filter performance is very difficult because of complexity of the defining physical and chemical events in the filtration system whereas the knowledge of functionality of filter coefficient. The main objec...Modeling of filter performance is very difficult because of complexity of the defining physical and chemical events in the filtration system whereas the knowledge of functionality of filter coefficient. The main objective of this study is to predict the performance of multimedia filter and to evaluate both the initial and transient stage of suspended solid removal efficiency depending on experimental data. Fuzzy logic has been used to build a model of multi input and one output (MISO) for the removal efficiency of multimedia filter which it consists from sand and granular activated carbon (GAC) mediums. The control parameters of (FLC) of Sugeno model are seven parameters which are media depths, media grains size for both sand and GAC, filtration rate, diameter of suspension particle, feed concentration, and operation time. The output parameter is removal efficiency of media filter whereas these data are collocated from pilot scale deep bed filter, thus, the removal efficiency of filter was modeled by 575 rules as a function of different control parameters. An adaptive of neuron fuzzy inference system (ANFIS) had used to simulate the experimental data. The simulation results were evaluated using mean absolute percentage error (MAPE), whereas the results showed that the prediction of ANFIS model has a good agreement with experimental data when the MAPE is equal to 7.0458 and fuzzy rule -based modeling proved a reliable and flexible tool to study the performance of multimedia filter. The conclusion showed that there is a relationship between flow rate, effective size and optimum bed depth for all filter media, the increment of effective size generates a higher value of optimum filter bed depth for a lower value of filtration rate. It was concluded that the optimal removal efficiency (95-100) achieved by (0.5-0.7 mm) grain size of sand, (1.5-1.9) mm grain size of granular activated carbon (GAC), with media depths should range from 0.3 to 0.6 m.展开更多
文摘This review provides an insight and up-to-date information on the application of Moringa oleifera seeds, the short falls of existing technologies as a coagulant and disinfectant in domestic water treatment. While the coagulant properties are well reported, the disinfectant properties are not well studied. Literatures on low cost alternative technologies such as the application of hiocoagulants and slow sand filters are extensively reported. However, there is limited work addressing the limitations of these technologies that have restricted its widespread use to solve the global soaring water crises. Slow sand filters have a very slow filtration rate that depends on the biofilm layer which takes about 17 days to form. Moringa oleifera treated water cannot last more than 48 hours without bacteria regrowth. Investigation of the best method of isolating coagulant component continues with differing opinions over the nature of its coagulant ingredient not resolved in ongoing literature. An attempt was made in this paper to highlight the advantages of a Moringa disinfectant sand filter hybrid system that can purify water. Microbiological advantages of this system in providing a 100% removal of pathogens, and engineering considerations such as water treatment within an hour residence time, faster flow rates, less clogging and backwashing could be some of the advantages ofa Moringa sand filter system. The need to focus on integrating Moringa and sand filter systems for more practical applications is recommended.
基金Supported by Key Project of National Water Pollution Control and Treatment Science and Technology(2014ZX07211-001)Demonstration Study on Integration Model of Environmental Public Utilities in Industrial Parks of Key Watershed(2014ZX07211-001-04)
文摘In order to protect quality of Baiyangdian surface water and Gaoyang groundwater,the project is applied to process printing and dyeing wastewater that contains complicated compositions,high concentrations of organics and SS,and lots of pollutants difficult to degrade by microorganism. The process and operating parameters of project are optimized and debugged,and its economic and environmental benefits are analyzed.The results show that the process of coagulation sedimentation-hydrolytic acidification with aeration tank-biological aerated filter-active sand filter is applied in Gaoyang Sewage Treatment Plant. The design scale of sewage treatment plant is 120000 m^3/d. The influent is as following: COD is 669mg/L; SS is 424mg/L; NH_3-N is 8.83mg/L; TP is 6.03mg/L. After the process,the best removal rates of COD,SS,NH_3-N and TP are 93. 5%,98. 8%,97. 1% and 96. 2%,respectively. The various indexes of effluent water complied with standard A of the first order in Pollutants Emission Standard of Urban Wastewater Treatment Plant( GB 18918-2002). The processing cost is only 0. 807 yuan/m^3. As a result,the project construction and operation not only improve the environment,but also promote regional economic development. Process design and operating parameters provide an important reference value for the printing and dyeing wastewater treatment industry.
文摘Rain water is an important source to feed the groundwater aquifer, whether directly or by harvesting and recharging. The importance of purification is for reducing the risk of pollutants from recharging runoff rainwater. The use of sand filter as a technique considered not expensive and commonly used for removing contaminants from water and wastewater treatment industries. The methodology used laboratory testing, by designing and constructing pilot plant to experiment the sand filter for purification, and made simulation for the infiltration of storm water through sand filter of 2 meters depth, in order to find the relationship between the depth on one hand, and the removal of suspended solids and fecal coliforms bacteria on the other hand, to know the effective depth that gets the purification. The research results during three days of infiltration show that the sand filter can remove fecal coliforms bacteria at a depth of 150 cm, and provide purified water with a concentration of suspended solids less than 20 mg/liter at a depth of 75 cm.
文摘In?ltration percolation is a rustic and extensive purifying technique which is capable of completely oxidizing and decontaminating wastewater. The object of the present study is to validate on a real scale the findings gotten in pilot laboratory. It is notably to confirming the purification performances and decontamination of secondary effluent by sand filter drained under an intense wild plant. For this, a basin of 100 m2 of infiltration surface equipped with two wells of sampling in the center and in the periphery, has been constructed in irrigated perimeter of Dissa in Gabes (south east of Tunisia). Our results show that essential of the COD is eliminated in first 50 centimeters in sand filter and the presence of wild plant on the surface of infiltration damaged quality of filtered water. The follow-up of the organic nitrogen and ammonium show the good performances of process in elimination of nitrogenous pollution. The rate of exhaustion is about 100% and this since first 50 centimeters of filtration. The sand filter retains the different shapes of the phosphor by adsorption and precipitation in the superficial horizon. The elimination of the bacterial pollution is high, it varying from 0.1 to 2.5 Ulog. The bacterial purification remained low after 50 cm filtration. Indeed, with 50 cm depth, the quality of the filtrate is slightly better than the influent with still tendency to higher removal in the center than in periphery of the basin.
文摘A novel integrated water treatment facility, inner-recycling continuous sand filter, is discussed. The theory of micro-flocculation is applied in the sand-washing circulation system with continuous filtration and backwashing. The design and operation parameters, which affect the performance of the filter, are discussed. The key design parameters are provided as follows: diameter of filter material is 0.7 to 1.0 mm, depth of filter bed is 0.6 m, filtration velocity is less than 12 m/h, ratio of gas to water is 9:11 and sand recycling rate is 2 to 4 mm/min.
基金This research was supported by the U.S.Department of Agriculture,Agricultural Research Service。
文摘The effects of uncoated and Fe-coated biochars(BC)on the removal of bacteria,microspheres,and dissolved reactive phosphorus(DRP)in sand filters were compared.Filters were packed with 1.2 or 2.0-mm sand mixed with 30%(vol/vol)uncoated BC,Fe-coated BC,or a control without BC.Removal of E.coli,Salmonella,and Enterococci increased from 23,42,and 25%in the unamended 1.2-mm sand to 48,80,and 75%in the uncoated BC treatment,though only the increase for Enterococci was significant(p<0.05).For the Fe-coated BC,removal efficiencies were 89,93,and 94%,respectively,which were all significantly(p<0.05)greater than the unamended sand but only the removal of E.coli was significantly greater than the uncoated BC sand filter.For the 2.0-mm sands,the only significant increase in removal following BC addition was observed for Salmonella.Trends in microsphere removal were generally consistent with bacteria.Removal of DRP in the unamended and uncoated BC filters was 33 and 13%(p>0.05),respectively,whereas removal in the Fe-coated BC filters was 98%(p<0.05).Results from batch sorption experiments indicate that both BCs similarly increased bacterial sorption to sand.In contrast,DRP sorption to the unamended and uncoated BC-amended sands were similar(p>0.05)with DRP sorption to the Fe-coated BC-amended sand being significantly greater(p<0.05).Results indicate that Fe-coated BC is more effective at retaining DRP than bacteria and microspheres in sand filters.
基金This research was part of USDA-ARS National Program 212:Soil and Air.
文摘The addition of biochar to sand columns can enhance the retention of bacteria and thus may provide a management strategy for removing bacteria from tile-drainage waters.In this study,the role of sand size as a factor in controlling microbial reten-tion in biochar-amended sand columns was investigated.Laboratory column experiments were conducted to quantify the removal of two bacterial isolates(E.coli and Salmonella)and polystyrene microspheres in 10-cm-long columns packed with clean sand of three different sizes(0.25,0.71,and 1.19 mm)at four biochar concentrations(0%,5%,10%,and 15%).Sorption studies were also performed to help identify the relative roles of sorption and physical straining on the removal of bacteria and microspheres within the columns.For the large sand,the log10 removal values(LRV)for E.coli increased from 0.22 to 0.49 for the 0%and 15%biochar concentrations,respectively,while LRV for Salmonella increased from 0.19 to 0.68.For the small sand,increasing biochar concentration from 0%to 15%increased LRV from 0.11 to 1.9 for E.coli and from 0.20 to 4.6 for Salmonella.In comparison,LRV for microspheres in the 15%biochar columns was only minimally higher than the unamended columns for all three sand sizes.Results from the sorption studies show that high sorption coefficients generally correlated with high LRV indicating that sorption rather than physical straining was the primary mechanism of retention in the columns.Results from this study further our understanding of bacterial retention in biochar-amended porous media.
基金the National Key R&D Program of China(No.2018YFE0204101)the National Natural Science Foundation of China(No.51778603)the Alliance of International Science Organizations(ANSO-CR-KP-2020-05).
文摘Backwashing is crucial for preventing clogging of sand filters.However,few studies have investigated the effect of backwashing on micropollutant removal and the dynamic changes in the microbial community in sand filters.Here,we used a series of manganese and quartz sand filters under empty bed contact times(EBCTs)of 2 h and 4 h to explore variations in micropollutant degradation and temporal dynamics of the microbial community after backwashing.The results showed that the removal efficiencies of caffeine,sulfamethoxazole,sulfadiazine,trimethoprim,atrazine,and active biomass recovered within 2 d after backwashing in both types of sand filters at 2-h EBCT,but the recovery of sulfadiazine and trimethoprim was not observed at 4-h EBCT.Moreover,the removal efficiency of atenolol increased after backwashing in the manganese sand filters,whereas maintained almost complete removal efficiency in the quartz sand filters at both EBCTs.Pearson correlation analysis indicated that microbial community composition gradually recovered to the pre-backwashing level(R increased from 0.53 to 0.97)at 2-h EBCT,but shifted at 4-h EBCT(R<0.25)after backwashing.Furthermore,the compositions of the recovered,depleted,and improved groups of microbes were distinguished by applying hierarchical clustering to the differentially abundant amplicon sequence variants.The cumulative relative abundance of recovered microbes at 2-h EBCT was 82.76%±0.43%and 46.82%±4.34%in the manganese and quartz sand filters,respectively.In contrast,at 4-h EBCT,the recovered microbes dropped to 15.55%–25.69%in both types of sand filters.
文摘Modeling of filter performance is very difficult because of complexity of the defining physical and chemical events in the filtration system whereas the knowledge of functionality of filter coefficient. The main objective of this study is to predict the performance of multimedia filter and to evaluate both the initial and transient stage of suspended solid removal efficiency depending on experimental data. Fuzzy logic has been used to build a model of multi input and one output (MISO) for the removal efficiency of multimedia filter which it consists from sand and granular activated carbon (GAC) mediums. The control parameters of (FLC) of Sugeno model are seven parameters which are media depths, media grains size for both sand and GAC, filtration rate, diameter of suspension particle, feed concentration, and operation time. The output parameter is removal efficiency of media filter whereas these data are collocated from pilot scale deep bed filter, thus, the removal efficiency of filter was modeled by 575 rules as a function of different control parameters. An adaptive of neuron fuzzy inference system (ANFIS) had used to simulate the experimental data. The simulation results were evaluated using mean absolute percentage error (MAPE), whereas the results showed that the prediction of ANFIS model has a good agreement with experimental data when the MAPE is equal to 7.0458 and fuzzy rule -based modeling proved a reliable and flexible tool to study the performance of multimedia filter. The conclusion showed that there is a relationship between flow rate, effective size and optimum bed depth for all filter media, the increment of effective size generates a higher value of optimum filter bed depth for a lower value of filtration rate. It was concluded that the optimal removal efficiency (95-100) achieved by (0.5-0.7 mm) grain size of sand, (1.5-1.9) mm grain size of granular activated carbon (GAC), with media depths should range from 0.3 to 0.6 m.
