The effects of biologically active carbon(BAC)filtration on haloacetic acid(HAA)levels in plant effluents and distribution systems were investigated using the United States Environmental Protection Agency’s Informati...The effects of biologically active carbon(BAC)filtration on haloacetic acid(HAA)levels in plant effluents and distribution systems were investigated using the United States Environmental Protection Agency’s Information Collection Rule(ICR)database.The results showed that average HAA5 concentrations in all locations were 20.4μg·L^(-1)and 29.6μg·L^(-1)in ICR plants with granular activated carbon(GAC)and ICR plants without GAC process,respectively.For plants without GAC,the highest HAA levels were observed in the quarters of April to June and July to September.However,for plants with GAC,the highest HAA levels were observed in the quarters of April to June and January to March.This HAA level profile inversely correlated well with water temperature,or biologic activity.For GAC plants,simulated distribution samples matched well with distribution system equivalent samples for Cl3AA and THMs.For plants with and without GAC,simulated distribution samples overestimated readily biodegradable HAAs in distribution systems.The study indicated that through HAA biodegradation,GAC process plays an important role in lowering HAA levels in finished drinking water.展开更多
Climate change is regarded as the greatest threat to society in the coming years, and directly affects the water industry;with changes in temperature, rainfall intensities and sea levels resulting in increased treatme...Climate change is regarded as the greatest threat to society in the coming years, and directly affects the water industry;with changes in temperature, rainfall intensities and sea levels resulting in increased treatment and subsequent energy costs. As one of the largest global consumers of energy, the water industry has the opportunity to significantly prevent climate change by reducing energy usage and subsequent carbon footprints. Wastewater treatment alone requires an estimated 1% - 3% of a country overall energy output while producing 1.6% of its global greenhouse gas emissions;over 75% of which can be due to the collection system. Gravity flows should therefore be incorporated where possible, reducing pumping requirements and therefore minimizing costs and subsequent carbon footprints. This study has assessed the operational energy usage of the alternative collection systems low pressure and vacuum, for use in situations in which a conventional gravity system is not practicable. This was carried out through hypothetical scenario testing using design parameters derived from literature, generating 60 hypothetical collection mains with variations in population, static head and main length. From this study, it was found that the energy demand of a low pressure system is 3.2 - 4.2 times greater than that of its equivalent vacuum system in the same scenario. Energy demand for both systems increases with population, static head and main length. However, population and therefore flow changes were found to have the greatest effect on the energy usage of both systems. Therefore, flow reduction measures should be adopted if the decarbonization of the water industry is to be achieved.展开更多
基金This study was supported by“Taiwan NSC”(No.96-2221-E-002-051)and“USEPA Small Public Water Technology Assistance Center”.
文摘The effects of biologically active carbon(BAC)filtration on haloacetic acid(HAA)levels in plant effluents and distribution systems were investigated using the United States Environmental Protection Agency’s Information Collection Rule(ICR)database.The results showed that average HAA5 concentrations in all locations were 20.4μg·L^(-1)and 29.6μg·L^(-1)in ICR plants with granular activated carbon(GAC)and ICR plants without GAC process,respectively.For plants without GAC,the highest HAA levels were observed in the quarters of April to June and July to September.However,for plants with GAC,the highest HAA levels were observed in the quarters of April to June and January to March.This HAA level profile inversely correlated well with water temperature,or biologic activity.For GAC plants,simulated distribution samples matched well with distribution system equivalent samples for Cl3AA and THMs.For plants with and without GAC,simulated distribution samples overestimated readily biodegradable HAAs in distribution systems.The study indicated that through HAA biodegradation,GAC process plays an important role in lowering HAA levels in finished drinking water.
文摘Climate change is regarded as the greatest threat to society in the coming years, and directly affects the water industry;with changes in temperature, rainfall intensities and sea levels resulting in increased treatment and subsequent energy costs. As one of the largest global consumers of energy, the water industry has the opportunity to significantly prevent climate change by reducing energy usage and subsequent carbon footprints. Wastewater treatment alone requires an estimated 1% - 3% of a country overall energy output while producing 1.6% of its global greenhouse gas emissions;over 75% of which can be due to the collection system. Gravity flows should therefore be incorporated where possible, reducing pumping requirements and therefore minimizing costs and subsequent carbon footprints. This study has assessed the operational energy usage of the alternative collection systems low pressure and vacuum, for use in situations in which a conventional gravity system is not practicable. This was carried out through hypothetical scenario testing using design parameters derived from literature, generating 60 hypothetical collection mains with variations in population, static head and main length. From this study, it was found that the energy demand of a low pressure system is 3.2 - 4.2 times greater than that of its equivalent vacuum system in the same scenario. Energy demand for both systems increases with population, static head and main length. However, population and therefore flow changes were found to have the greatest effect on the energy usage of both systems. Therefore, flow reduction measures should be adopted if the decarbonization of the water industry is to be achieved.
