Reactions between humic acid solutions and excessive ClO2 or Cl2 have been investigated. Under various experimental conditions, the removal efficiency of TOC, UV254and A410 from humic acid solutions were examined. The...Reactions between humic acid solutions and excessive ClO2 or Cl2 have been investigated. Under various experimental conditions, the removal efficiency of TOC, UV254and A410 from humic acid solutions were examined. The relationship between the removal efficiency and the consumption of ClO2 or Cl2 was discussed. The results showed that the maximum demand of ClO2 was 2.19 mg/mg TOC for the humic acid solution under the experimental conditions, and that of ClO2 was 1.88 mg/mg TOC. The variation tendency of ClO2 consumption was similar to that of Cl2. TOC of humic acid solutions decreased 15.2% and 15.6% after the reaction with ClO2 or Cl2 respectively. Under the experimental conditions, 21.4% of unsaturated bonds and 52.8% of humic acid color were removed by ClO2 in 168 h. As for Cl2, removal efficiency of unsaturated bonds and humic acid color were 16.8% and 41.7% respectively. Larger molecules from humic acid were oxidized to smaller molecules by ClO2 and Cl2. Higher oxidation potential of ClO2 than that of Cl2 was also indicated by variation of UV254/A410 ratios. The similar tendency, that exhibited faster variation in the initial 24 h, existed for all the research factors.展开更多
This study was considered to assess the risk of alum which is used in Sudan for drinking water treatment purposes for a long period without toxicity freedom records .Newzealand rabbits were chosen for animal phase tri...This study was considered to assess the risk of alum which is used in Sudan for drinking water treatment purposes for a long period without toxicity freedom records .Newzealand rabbits were chosen for animal phase trials, divided into 3 groups. One group was the undosed controls. Test groups were given alum at dose rates of 1% and 20% respectively for two groups after an adaptation period. Clinical signs were observed together with postmortem and histopathological examinations. Chemical investigations included enzymatic, metabolic, electrolyte and hematological changes. The test rabbits demonstrated low voice, inappitence, whitish salivation, watery diarrhea and recumbence followed by emphysematous, lungs, electrolyte imbalance, renal dysfunctions, stiff focal inflammation of the empty intestines and congested liver with white spots. The control group was normal .On atomic absorption only the lungs kept residual alum, while the livers washed- out the substance ,may be via bile .Alum -dosed rabbits showed necrosis in the cortex and medulla of the kidney, emphysema in the lungs and necrosis in the hepatocytes. On evaluation of the above results, alum was considered to be toxic to Newzealand rabbits at dose rates tried.展开更多
基金Natural Science Foundation of China (No50478103)State Key Project for Small Towns Development of Ministry of Science and Technology of China (No2003BA808A17)
文摘Reactions between humic acid solutions and excessive ClO2 or Cl2 have been investigated. Under various experimental conditions, the removal efficiency of TOC, UV254and A410 from humic acid solutions were examined. The relationship between the removal efficiency and the consumption of ClO2 or Cl2 was discussed. The results showed that the maximum demand of ClO2 was 2.19 mg/mg TOC for the humic acid solution under the experimental conditions, and that of ClO2 was 1.88 mg/mg TOC. The variation tendency of ClO2 consumption was similar to that of Cl2. TOC of humic acid solutions decreased 15.2% and 15.6% after the reaction with ClO2 or Cl2 respectively. Under the experimental conditions, 21.4% of unsaturated bonds and 52.8% of humic acid color were removed by ClO2 in 168 h. As for Cl2, removal efficiency of unsaturated bonds and humic acid color were 16.8% and 41.7% respectively. Larger molecules from humic acid were oxidized to smaller molecules by ClO2 and Cl2. Higher oxidation potential of ClO2 than that of Cl2 was also indicated by variation of UV254/A410 ratios. The similar tendency, that exhibited faster variation in the initial 24 h, existed for all the research factors.
文摘This study was considered to assess the risk of alum which is used in Sudan for drinking water treatment purposes for a long period without toxicity freedom records .Newzealand rabbits were chosen for animal phase trials, divided into 3 groups. One group was the undosed controls. Test groups were given alum at dose rates of 1% and 20% respectively for two groups after an adaptation period. Clinical signs were observed together with postmortem and histopathological examinations. Chemical investigations included enzymatic, metabolic, electrolyte and hematological changes. The test rabbits demonstrated low voice, inappitence, whitish salivation, watery diarrhea and recumbence followed by emphysematous, lungs, electrolyte imbalance, renal dysfunctions, stiff focal inflammation of the empty intestines and congested liver with white spots. The control group was normal .On atomic absorption only the lungs kept residual alum, while the livers washed- out the substance ,may be via bile .Alum -dosed rabbits showed necrosis in the cortex and medulla of the kidney, emphysema in the lungs and necrosis in the hepatocytes. On evaluation of the above results, alum was considered to be toxic to Newzealand rabbits at dose rates tried.
