To compare the treatment effects and the costs of coagulation/Fenton process and Fenton/coagulation process in leachate treatment,fresh and old leachates were respestively treated with these two techniques.The experim...To compare the treatment effects and the costs of coagulation/Fenton process and Fenton/coagulation process in leachate treatment,fresh and old leachates were respestively treated with these two techniques.The experimental results indicate that the highest chemical oxygen demand(COD)removal rate of Fenton reaction on leachate can be acquired under the conditions of pH=3.5,nH2O2/nFe2+=6,mH2O2/mCOD=3,and reaction time=4 h.Polyaluminium chloride(PAC)coagulation has the highest COD removal rate on leachate under the condition of mPAC/mCOD=0.6.Under the optimum reaction conditions,coagulation/Fenton and Fenton/coagulation processes were respestively adopted to treat raw leachate.The data also show that COD removal rate of coagulation/Fenton process on fresh and old leachates are 90.56% and 86.52% respectively and that of Fenton/coagulation process 89.99% and 85.99%,so there is no obvious difference.But the cost of coagulation/Fenton process for leachate treatment is RMB 62.6,lower than that of Fenton/coagulation process.Therefore,coagulation/Fenton process is more optimized than Fenton/coagulation process for leachate treatment.展开更多
Nearly 97% of organic chemicals in Hong Kong leachate could be effectively removed by the UASB(upflow anaerobic sludge blanket) process followed by the fenton coagulation. The COD of leachate was lowered from an avera...Nearly 97% of organic chemicals in Hong Kong leachate could be effectively removed by the UASB(upflow anaerobic sludge blanket) process followed by the fenton coagulation. The COD of leachate was lowered from an average of 12900 mg/L to 1440 mg/L after the UASB treatment, and was further lowered to 394 mg/L after the fenton coagulation. The remaining refractory residues could be further removed by ozonation with the addition of H 2O 2. The ozonation for the supernatant of the fenton coagulation was most effective at pH 7—8, with the addition of 300 mg/L of H 2O 2, and 30 min of reaction. The final effluent contained only 85 mg/L of COD and l0 mg/L of BOD 5. On the other hand, direct ozonation of UASB effluent lowered the COD to 905 mg/L and BOD 5 to l03 mg/L. Ozonation improved the biodegradability of the organic residues, and also converted part of organic\|N in the leachate into NH 3 N and NO - 3\|N.展开更多
Fenton oxidation is a promising water treatment method to degrade organic pollutants. In this study, 30 different organic compounds were selected and their reaction rate constants（k） were determined for the Fenton o...Fenton oxidation is a promising water treatment method to degrade organic pollutants. In this study, 30 different organic compounds were selected and their reaction rate constants（k） were determined for the Fenton oxidation process. Gaussian09 and Material Studio software sets were used to carry out calculations and obtain values of 10 different molecular descriptors for each studied compound. Ferric-oxyhydroxide coagulation experiments were conducted to determine the coagulation percentage. Based upon the adsorption capacity,all of the investigated organic compounds were divided into two groups（Group A and Group B）. The percentage adsorption of organic compounds in Group A was less than 15%（wt./wt.）and that in the Group B was higher than 15%（wt./wt.）. For Group A, removal of the compounds by oxidation was the dominant process while for Group B, removal by both oxidation and coagulation（as a synergistic process） took place. Results showed that the relationship between the rate constants（k values） and the molecular descriptors of Group A was more pronounced than for Group B compounds. For the oxidation-dominated process,EHOMOand Fukui indices（f（0）_x, f（-）_x, f（＋）_x） were the most significant factors. The influence of bond order was more significant for the synergistic process of oxidation and coagulation than for the oxidation-dominated process. The influences of all other molecular descriptors on the synergistic process were weaker than on the oxidation-dominated process.展开更多
基金National Key Project of Water Pollution Control and Treatment Technology,China(No.2008ZX0720700902)
文摘To compare the treatment effects and the costs of coagulation/Fenton process and Fenton/coagulation process in leachate treatment,fresh and old leachates were respestively treated with these two techniques.The experimental results indicate that the highest chemical oxygen demand(COD)removal rate of Fenton reaction on leachate can be acquired under the conditions of pH=3.5,nH2O2/nFe2+=6,mH2O2/mCOD=3,and reaction time=4 h.Polyaluminium chloride(PAC)coagulation has the highest COD removal rate on leachate under the condition of mPAC/mCOD=0.6.Under the optimum reaction conditions,coagulation/Fenton and Fenton/coagulation processes were respestively adopted to treat raw leachate.The data also show that COD removal rate of coagulation/Fenton process on fresh and old leachates are 90.56% and 86.52% respectively and that of Fenton/coagulation process 89.99% and 85.99%,so there is no obvious difference.But the cost of coagulation/Fenton process for leachate treatment is RMB 62.6,lower than that of Fenton/coagulation process.Therefore,coagulation/Fenton process is more optimized than Fenton/coagulation process for leachate treatment.
文摘Nearly 97% of organic chemicals in Hong Kong leachate could be effectively removed by the UASB(upflow anaerobic sludge blanket) process followed by the fenton coagulation. The COD of leachate was lowered from an average of 12900 mg/L to 1440 mg/L after the UASB treatment, and was further lowered to 394 mg/L after the fenton coagulation. The remaining refractory residues could be further removed by ozonation with the addition of H 2O 2. The ozonation for the supernatant of the fenton coagulation was most effective at pH 7—8, with the addition of 300 mg/L of H 2O 2, and 30 min of reaction. The final effluent contained only 85 mg/L of COD and l0 mg/L of BOD 5. On the other hand, direct ozonation of UASB effluent lowered the COD to 905 mg/L and BOD 5 to l03 mg/L. Ozonation improved the biodegradability of the organic residues, and also converted part of organic\|N in the leachate into NH 3 N and NO - 3\|N.
基金supported by the National Natural Science Funds of China (No. NSFC21177083)the Shanghai Municipal Commission of Economy and Informatization Project (No. CXY-2013-52)
文摘Fenton oxidation is a promising water treatment method to degrade organic pollutants. In this study, 30 different organic compounds were selected and their reaction rate constants（k） were determined for the Fenton oxidation process. Gaussian09 and Material Studio software sets were used to carry out calculations and obtain values of 10 different molecular descriptors for each studied compound. Ferric-oxyhydroxide coagulation experiments were conducted to determine the coagulation percentage. Based upon the adsorption capacity,all of the investigated organic compounds were divided into two groups（Group A and Group B）. The percentage adsorption of organic compounds in Group A was less than 15%（wt./wt.）and that in the Group B was higher than 15%（wt./wt.）. For Group A, removal of the compounds by oxidation was the dominant process while for Group B, removal by both oxidation and coagulation（as a synergistic process） took place. Results showed that the relationship between the rate constants（k values） and the molecular descriptors of Group A was more pronounced than for Group B compounds. For the oxidation-dominated process,EHOMOand Fukui indices（f（0）_x, f（-）_x, f（＋）_x） were the most significant factors. The influence of bond order was more significant for the synergistic process of oxidation and coagulation than for the oxidation-dominated process. The influences of all other molecular descriptors on the synergistic process were weaker than on the oxidation-dominated process.
