To investigate the characteristics of disinfection by-products （DBPs） in an actual water distribution system using the raw water with high bromide ion concentration, the composition and concentration of trihalometha...To investigate the characteristics of disinfection by-products （DBPs） in an actual water distribution system using the raw water with high bromide ion concentration, the composition and concentration of trihalomethanes （THMs） formed by chlorination of the water in the presence of bromide ion were measured in a city water distribution system during one year. The results show that brominated THMs contributed a great part （83%-89% ） to the index for additive toxicity （ATI） and resulted in the ATI of most of the samples exceeding WHO guideline standard for total THMs （ TTHMs）, especially during the summer （ rainy season）. This indicates that the chlorination of water in the presence of bromide ion leaded to high ratios of brominated THMs to TrHMs. However, a visible increase in the concentration of THMs with increasing residence time in the distribution system was not observed. Additionally, based on alternatives analysis, packed tower aeration method is proposed to reduce THMs level of the finished water leaving the treatment plant.展开更多
Washing is a promising method for separating contaminants bound to the particles of soil ex-situ by chemical mobilization. Laboratory batch washing experi- ments were conducted using deionized water and varying concen...Washing is a promising method for separating contaminants bound to the particles of soil ex-situ by chemical mobilization. Laboratory batch washing experi- ments were conducted using deionized water and varying concentrations of oxalic acid, citric acid, tartaric acid, acetic acid, hydrochloric acid and ethylenediaminetetra acetic acid （EDTA） to assess the efficiency of using these chemicals as washing agents and to clean up heavy metals from two heavily polluted soils from an iron and streel smelting site. The toxicity reduction index and remediation costs were analyzed, and the results showed that the soils were polluted with Cd, Pb and Zn. Hydrochloric acid and EDTA were more efficient than the other washing agents in the remediation of the test soils. The maximum total toxicity reduction index showed that 0.5 mol·L^-1 hydro- chloric acid could achieve the remediation with the lowest costs.展开更多
基金National High-Tech Research and Development Program of China ( 863 Program ) ( No.2007AA06Z303)
文摘To investigate the characteristics of disinfection by-products （DBPs） in an actual water distribution system using the raw water with high bromide ion concentration, the composition and concentration of trihalomethanes （THMs） formed by chlorination of the water in the presence of bromide ion were measured in a city water distribution system during one year. The results show that brominated THMs contributed a great part （83%-89% ） to the index for additive toxicity （ATI） and resulted in the ATI of most of the samples exceeding WHO guideline standard for total THMs （ TTHMs）, especially during the summer （ rainy season）. This indicates that the chlorination of water in the presence of bromide ion leaded to high ratios of brominated THMs to TrHMs. However, a visible increase in the concentration of THMs with increasing residence time in the distribution system was not observed. Additionally, based on alternatives analysis, packed tower aeration method is proposed to reduce THMs level of the finished water leaving the treatment plant.
文摘Washing is a promising method for separating contaminants bound to the particles of soil ex-situ by chemical mobilization. Laboratory batch washing experi- ments were conducted using deionized water and varying concentrations of oxalic acid, citric acid, tartaric acid, acetic acid, hydrochloric acid and ethylenediaminetetra acetic acid （EDTA） to assess the efficiency of using these chemicals as washing agents and to clean up heavy metals from two heavily polluted soils from an iron and streel smelting site. The toxicity reduction index and remediation costs were analyzed, and the results showed that the soils were polluted with Cd, Pb and Zn. Hydrochloric acid and EDTA were more efficient than the other washing agents in the remediation of the test soils. The maximum total toxicity reduction index showed that 0.5 mol·L^-1 hydro- chloric acid could achieve the remediation with the lowest costs.
