Both a theoretical and an empirical model were developed for predicting the formation of soluble microbial products(SMP) during drinking water biofiltration.Four pilot-scale biofilters with ceramsite as the medium wer...Both a theoretical and an empirical model were developed for predicting the formation of soluble microbial products(SMP) during drinking water biofiltration.Four pilot-scale biofilters with ceramsite as the medium were fed with different acetate loadings for the determination of SMP formation.Using numerically simulated and measured parameters,the theoretical model was developed according to the substrate and biomass balance.The results of this model matched the measured data better for higher SMP formation but did not fit well when SMP formation was lower.In order to better simulate the reality and overcome the difficulties of measuring the kinetic parameters,a simpler empirical model was also developed.In this model,SMP formation was expressed as a function of fed organic loadings and the depth of the medium,and a much better fit was obtained.展开更多
Objective To investigate the reduction of chlorination by-products (CBPs) precursors using the fluidized-bed biofilm reactor (FBBR). Methods Reduction of total organic carbon (TOC), ultraviolet absorbance (UV254), tri...Objective To investigate the reduction of chlorination by-products (CBPs) precursors using the fluidized-bed biofilm reactor (FBBR). Methods Reduction of total organic carbon (TOC), ultraviolet absorbance (UV254), trihalomethane (THM) formation potential (THMFP), haloacetic acid (HAA) formation potential (HAAFP), and ammonia in FBBR were evaluated in detail. Results The reduction of TOC or UV254 was low, on average 12.6% and 4.7%, respectively, while the reduction of THMFP and HAAFP was significant. The reduction of ammonia was 30%-40% even below 3℃, however, it could quickly rise to over 50% above 3℃. Conclusions The FBBR effectively reduces CBPs and ammonia in drinking water even at low temperature and seems to be a very promising and competitive drinking water reactor for polluted surface source waters, especially in China.展开更多
Objective Since haloacetic acids (HAAs), which are nonvolatile and of high carcinogenic risk, are common species of chlorinated disinfection by-products(DBPs) in drinking water, and little has been known in China, it ...Objective Since haloacetic acids (HAAs), which are nonvolatile and of high carcinogenic risk, are common species of chlorinated disinfection by-products(DBPs) in drinking water, and little has been known in China, it is necessary to make a survey about the kinds and levels of HAAs in drinking water of the nation. Method HAAs were analyzed using gas chromatography with electron capture detector(GC/ECD) and relatively complex pretreatment process of sample was applied. Five main cities in different areas of China were chosen in the survey. Results Studies showed that the main species of HAAs in drinking water in China were DCAA and TCAA, ranging from 0.4 礸/L to 12.85 礸/L and from 0.56 礸/L to 10.98 礸/L, respectively. MBAA and DBAA were also detected in one city, ranging from 2.20 礸/L to 4.95 礸/L and 1.10 礸/L to 2.81 礸/L, respectively. Therefore, the contents of HAAs varied, usually no more than 25 礸/L. Based on the acquired data to date, it is known that the concentrations of HAAs in drinking water in China were surely under the limits of Sanitary Standard for Drinking Water Quality (China, 2001). Conclusion A wider survey of HAAs in drinking water should be conducted throughout the nation to get adequate data and information, the ultimate aim of which is to control HAAs pollution and keep the balance between microbiological safety insurance and chemical risk control, minimize the formation of DBPs and ensure the safety of water supply at the same time.展开更多
The present drinking water purification system in Egypt uses surface water as a raw water supply without a preliminary filtration process.On the other hand,chlorine gas is added as a disinfectant agent in two steps,pr...The present drinking water purification system in Egypt uses surface water as a raw water supply without a preliminary filtration process.On the other hand,chlorine gas is added as a disinfectant agent in two steps,pre-and post-chlorination.Due to these reasons most of water treatment plants suffer low filtering effectiveness and produce the trihalomethane(THM) species as a chlorination by-product.The Ismailia Canal represents the most distal downstream of the main Nile River.Thus its water contains all the proceeded pollutants discharged into the Nile.In addition,the downstream reaches of the canal act as an agricultural drain during the closing period of the High Dam gates in January and February every year.Moreover,the wide industrial zone along the upstream course of the canal enriches the canal water with high concentrations of heavy metals.The obtained results indicate that the canal gains up to 24.06×106 m3 of water from the surrounding shallow aquifer during the closing period of the High Dam gates,while during the rest of the year,the canal acts as an influent stream losing about 99.6×106 m3 of its water budget.The reduction of total organic carbon(TOC) and suspended particulate matters(SPMs) should be one of the central goals of any treatment plan to avoid the disinfectants by-products.The combination of sedimentation basins,gravel pre-filtration and slow sand filtration,and underground passage with microbiological oxidation-reduction and adsorption criteria showed good removal of parasites and bacteria and complete elimination of TOC,SPM and heavy metals.Moreover,it reduces the use of disinfectants chemicals and lowers the treatment costs.However,this purification system under the arid climate prevailing in Egypt should be tested and modified prior to application.展开更多
Sustaining a reliable and contaminant-free drinking water is becoming an increasing challenge worldwide due to human activity, industrial waste, and agricultural overuse. Surface water is the main source of drinking w...Sustaining a reliable and contaminant-free drinking water is becoming an increasing challenge worldwide due to human activity, industrial waste, and agricultural overuse. Surface water is the main source of drinking water around the world. However, groundwater is also becoming increasingly popular, due to its clarity and minimal need for processing to reduce turbidity. Over the years, the demand and growth in the agricultural industry has also been the means of groundwater contamination. Due to the health burden that raw water can pose, water must be processed and purified prior to consumption. Raw water quality can be compromised by physical, chemical (heavy metals and disinfection by-products), and biological contaminants. Biological contaminants can significantly impact immunocompromised populations, while chemical contaminants can impact the growth and development of young children. Although obtaining a steady and high-quality water flow to the general population is an increasing challenge, developed countries have utilized state-of-the-art technologies and techniques to provide contaminant-free water to their citizens. This research aims to provide information about the regulatory parameters, characteristics, and sources of safe drinking water in the world as a model for future use in the developing world. In this, secondary data was used to compare and contrast drinking water quality among countries in the European Union, the United States, Canada, the United Kingdom, Singapore, New Zealand, Australia, Qatar, and the United Arab Emirates. The data indicates that Ireland and the United Kingdom have relatively lower amounts of contaminants in their drinking water. Upon completing this research, it is recommended that countries desiring clean drinking water systems should initiate and invest in programs that control and protect treatment plants, water distribution systems, water sources, and catchments.展开更多
The occurrence of 28 pharmaceuticals and personal care products(PPCPs)was investigated in 17 surface water samples(rivers,canals,and lagoons),12 groundwater samples(wells and boreholes,which can also be consumed for d...The occurrence of 28 pharmaceuticals and personal care products(PPCPs)was investigated in 17 surface water samples(rivers,canals,and lagoons),12 groundwater samples(wells and boreholes,which can also be consumed for drinking)and 8 drinking water samples(bottles and sachets)during dry and rainy seasons in Lagos state,Nigeria.The most prevalent compound detected in all samples was amoxicillin(an antibiotic)at median concentrations of 1614,238 and 358 ng/L in surface water,ground water and drinking water,respectively.This is of concern due to potential impact on development of antibioticresistant microbial strains.Other frequently-detected compounds include acetaminophen,nicotine,ibuprofen,and codeine with detection frequencies of more than 70%.Investigation of seasonal variability revealed that glyburide,caffeine,naproxen and diclofenac concentrations were significantly(P<0.05)higher during the dry season(winter),while Nicotine and Codeine levels were higher during the rainy season(summer).The factors influencing such seasonal variability include:dilution by extensive rainfall,agricultural activity(for nicotine)and usage patterns of pharmaceuticals among the local community.Measured concentrations in drinking water samples were used to assess inadvertent human exposure to PPCPs in Nigerian adults.Results revealed average daily exposures of 81,14 and 3 ngƩPPCPs/kg BW/day via drinking borehole,sachet water and bottled water,respectively.While there exists no health-based limit value(HBLV)for chronic exposure to mixtures of PPCPs,our results raise concern and warrant further investigation of the potential health implications of such unintended PPCPs exposure.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 50408026)
文摘Both a theoretical and an empirical model were developed for predicting the formation of soluble microbial products(SMP) during drinking water biofiltration.Four pilot-scale biofilters with ceramsite as the medium were fed with different acetate loadings for the determination of SMP formation.Using numerically simulated and measured parameters,the theoretical model was developed according to the substrate and biomass balance.The results of this model matched the measured data better for higher SMP formation but did not fit well when SMP formation was lower.In order to better simulate the reality and overcome the difficulties of measuring the kinetic parameters,a simpler empirical model was also developed.In this model,SMP formation was expressed as a function of fed organic loadings and the depth of the medium,and a much better fit was obtained.
基金This work was supported by National Natural Science Foundation of China (No. 50408006).
文摘Objective To investigate the reduction of chlorination by-products (CBPs) precursors using the fluidized-bed biofilm reactor (FBBR). Methods Reduction of total organic carbon (TOC), ultraviolet absorbance (UV254), trihalomethane (THM) formation potential (THMFP), haloacetic acid (HAA) formation potential (HAAFP), and ammonia in FBBR were evaluated in detail. Results The reduction of TOC or UV254 was low, on average 12.6% and 4.7%, respectively, while the reduction of THMFP and HAAFP was significant. The reduction of ammonia was 30%-40% even below 3℃, however, it could quickly rise to over 50% above 3℃. Conclusions The FBBR effectively reduces CBPs and ammonia in drinking water even at low temperature and seems to be a very promising and competitive drinking water reactor for polluted surface source waters, especially in China.
文摘Objective Since haloacetic acids (HAAs), which are nonvolatile and of high carcinogenic risk, are common species of chlorinated disinfection by-products(DBPs) in drinking water, and little has been known in China, it is necessary to make a survey about the kinds and levels of HAAs in drinking water of the nation. Method HAAs were analyzed using gas chromatography with electron capture detector(GC/ECD) and relatively complex pretreatment process of sample was applied. Five main cities in different areas of China were chosen in the survey. Results Studies showed that the main species of HAAs in drinking water in China were DCAA and TCAA, ranging from 0.4 礸/L to 12.85 礸/L and from 0.56 礸/L to 10.98 礸/L, respectively. MBAA and DBAA were also detected in one city, ranging from 2.20 礸/L to 4.95 礸/L and 1.10 礸/L to 2.81 礸/L, respectively. Therefore, the contents of HAAs varied, usually no more than 25 礸/L. Based on the acquired data to date, it is known that the concentrations of HAAs in drinking water in China were surely under the limits of Sanitary Standard for Drinking Water Quality (China, 2001). Conclusion A wider survey of HAAs in drinking water should be conducted throughout the nation to get adequate data and information, the ultimate aim of which is to control HAAs pollution and keep the balance between microbiological safety insurance and chemical risk control, minimize the formation of DBPs and ensure the safety of water supply at the same time.
基金Project supported by the German Academic Exchange Services(Deutcher Akademischer Austausch Dienst (DAAD)
文摘The present drinking water purification system in Egypt uses surface water as a raw water supply without a preliminary filtration process.On the other hand,chlorine gas is added as a disinfectant agent in two steps,pre-and post-chlorination.Due to these reasons most of water treatment plants suffer low filtering effectiveness and produce the trihalomethane(THM) species as a chlorination by-product.The Ismailia Canal represents the most distal downstream of the main Nile River.Thus its water contains all the proceeded pollutants discharged into the Nile.In addition,the downstream reaches of the canal act as an agricultural drain during the closing period of the High Dam gates in January and February every year.Moreover,the wide industrial zone along the upstream course of the canal enriches the canal water with high concentrations of heavy metals.The obtained results indicate that the canal gains up to 24.06×106 m3 of water from the surrounding shallow aquifer during the closing period of the High Dam gates,while during the rest of the year,the canal acts as an influent stream losing about 99.6×106 m3 of its water budget.The reduction of total organic carbon(TOC) and suspended particulate matters(SPMs) should be one of the central goals of any treatment plan to avoid the disinfectants by-products.The combination of sedimentation basins,gravel pre-filtration and slow sand filtration,and underground passage with microbiological oxidation-reduction and adsorption criteria showed good removal of parasites and bacteria and complete elimination of TOC,SPM and heavy metals.Moreover,it reduces the use of disinfectants chemicals and lowers the treatment costs.However,this purification system under the arid climate prevailing in Egypt should be tested and modified prior to application.
文摘Sustaining a reliable and contaminant-free drinking water is becoming an increasing challenge worldwide due to human activity, industrial waste, and agricultural overuse. Surface water is the main source of drinking water around the world. However, groundwater is also becoming increasingly popular, due to its clarity and minimal need for processing to reduce turbidity. Over the years, the demand and growth in the agricultural industry has also been the means of groundwater contamination. Due to the health burden that raw water can pose, water must be processed and purified prior to consumption. Raw water quality can be compromised by physical, chemical (heavy metals and disinfection by-products), and biological contaminants. Biological contaminants can significantly impact immunocompromised populations, while chemical contaminants can impact the growth and development of young children. Although obtaining a steady and high-quality water flow to the general population is an increasing challenge, developed countries have utilized state-of-the-art technologies and techniques to provide contaminant-free water to their citizens. This research aims to provide information about the regulatory parameters, characteristics, and sources of safe drinking water in the world as a model for future use in the developing world. In this, secondary data was used to compare and contrast drinking water quality among countries in the European Union, the United States, Canada, the United Kingdom, Singapore, New Zealand, Australia, Qatar, and the United Arab Emirates. The data indicates that Ireland and the United Kingdom have relatively lower amounts of contaminants in their drinking water. Upon completing this research, it is recommended that countries desiring clean drinking water systems should initiate and invest in programs that control and protect treatment plants, water distribution systems, water sources, and catchments.
文摘The occurrence of 28 pharmaceuticals and personal care products(PPCPs)was investigated in 17 surface water samples(rivers,canals,and lagoons),12 groundwater samples(wells and boreholes,which can also be consumed for drinking)and 8 drinking water samples(bottles and sachets)during dry and rainy seasons in Lagos state,Nigeria.The most prevalent compound detected in all samples was amoxicillin(an antibiotic)at median concentrations of 1614,238 and 358 ng/L in surface water,ground water and drinking water,respectively.This is of concern due to potential impact on development of antibioticresistant microbial strains.Other frequently-detected compounds include acetaminophen,nicotine,ibuprofen,and codeine with detection frequencies of more than 70%.Investigation of seasonal variability revealed that glyburide,caffeine,naproxen and diclofenac concentrations were significantly(P<0.05)higher during the dry season(winter),while Nicotine and Codeine levels were higher during the rainy season(summer).The factors influencing such seasonal variability include:dilution by extensive rainfall,agricultural activity(for nicotine)and usage patterns of pharmaceuticals among the local community.Measured concentrations in drinking water samples were used to assess inadvertent human exposure to PPCPs in Nigerian adults.Results revealed average daily exposures of 81,14 and 3 ngƩPPCPs/kg BW/day via drinking borehole,sachet water and bottled water,respectively.While there exists no health-based limit value(HBLV)for chronic exposure to mixtures of PPCPs,our results raise concern and warrant further investigation of the potential health implications of such unintended PPCPs exposure.
