Optimization of H_2O_2 dosage in microwave-H_2O_2 process for sludge pretreatment with uniform design method

A microwave-H2O2 process for sludge pretreatment exhibited high efficiencies of releasing organics,nitrogen,and phosphorus,but large quantities of H2O2 residues were detected.A uniform design method was thus employed in this study to further optimize H2O2 dosage by investigating effects of pH and H2O2 dosage on the amount of H2O2 residue and releases of organics,nitrogen,and phosphorus.A regression model was established with pH and H2O2 dosage as the independent variables,and H2O2 residue and releases of organics,nitrogen,and phosphorus as the dependent variables.In the optimized microwave-H2O2 process,the pH value of the sludge was firstly adjusted to 11.0,then the sludge was heated to 80°C and H2O2 was dosed at a H2O2:mixed liquor suspended solids(MLSS)ratio of 0.2,and the sludge was finally heated to 100°C by microwave irradiation.Compared to the microwave-H2O2 process without optimization,the H2O2 dosage and the utilization rate of H2O2 in the optimized microwave-H2O2 process were reduced by 80% and greatly improved by 3.87 times,respectively,when the H2O2:MLSS dosage ratio was decreased from 1.0 to 0.2,resulting in nearly the same release rate of soluble chemical oxygen demand in the microwave-H2O2 process without optimization at H2O2:MLSS ratio of 0.5.

Adsorption and biodegradation of three selected endocrine disrupting chemicals in river-based artificial groundwater recharge with reclaimed municipal wastewater

Endocrine disrupting chemical(EDC) pollution in river-based artificial groundwater recharge using reclaimed municipal wastewater poses a potential threat to groundwater-based drinking water supplies in Beijing, China. Lab-scale leaching column experiments simulating recharge were conducted to study the adsorption, biodegradation, and transport characteristics of three selected EDCs: 17β-estradiol(E2), 17α-ethinylestradiol(EE2) and bisphenol A(BPA). The three recharge columns were operated under the conditions of continual sterilization recharge(CSR), continual recharge(CR), and wetting and drying alternative recharge(WDAR). The results showed that the attenuation effect of the EDCs was in the order of WDAR > CR > CSR system and E2 > EE2 > BPA, which followed first-order kinetics. The EDC attenuation rate constants were 0.0783, 0.0505, and 0.0479 m-1 for E2, EE2 and BPA in the CR system, respectively. The removal rates of E2, EE2, and BPA in the CR system were 98%, 96% and 92%, which mainly depended on biodegradation and were affected by water temperature.In the CR system, the concentrations of BPA, EE2, and E2 in soil were 4, 6 and 10 times higher than in the WDAR system, respectively. According to the DGGE fingerprints, the bacterial community in the bottom layer was more diverse than in the upper layer, which was related to the EDC concentrations in the water-soil system. The dominant group was found to be proteobacteria, including Betaproteobacteria and Alphaproteobacteria, suggesting that these microbes might play an important role in EDC degradation.

Referential significance of sulfur isotopes and separation of S species in black shales of Southwest China

The states of S species in black shales are very complex, such as organic sulfur, pyrite sulfur and sulphate sulfur. The mineral microtexture, sulfur content and sulfur isotope can indicate the formation conditions and diagenetic processes of the black shales. The S species are separated perfectly and the relation between the content, mineral microtexture and

Discovery of mega-thick oil sandstone and asphalt in the Jurassic System in the Tula Basin and its significance

The mega_thick oil_bearing sandstone has been discovered in the Jurassic System in the Tula Basin, among which there are asphalt veins in fractures. The crude oil from oil_bearing sandstone and asphalt in the basin is mature, and similar to that of the Jurassic crude oil in the Qaidam Basin in geochemistry. The discovery not only shows that the Tula Basin can generate hydrocarbon and take on great exploration prospects but also has great implications for the oil and gas exploration in the Qaidam Basin.