High-concentration nitrite-containing wastewater that presents extreme toxicity to human health and organisms is difficult to be treated using traditional biological process. In this study, a novel microwave-enhanced ...High-concentration nitrite-containing wastewater that presents extreme toxicity to human health and organisms is difficult to be treated using traditional biological process. In this study, a novel microwave-enhanced chemical reduction process （MECRP） using sulfarninic acid （SA） was proposed as a new manner to treat such type of wastewater. Based on lab-scale experiments, it was shown that 75%-80% nitrite （NO2-） could be removed within time as short as 4 min under 50 W microwave irradiation in pH range 5-10 when molar ratio of SA to nitrite （SA/NO2-） was 0.8. Pilot-scale investigations demonstrated that MECRP was able to achieve nitrite and chemical oxygen demand （COD） removal with efficiency up to 80% and 20%, respectively under operating conditions of SA concentration 80 kg/m3, SA/NO2- ratio 0.8, microwave power 3.4 kW, and stirring time 3 min. Five-day biological oxygen demand （BODs）/COD value of treated effluent after MECRP was increased from 0.05 to 0.36 （by 620%）, which clearly suggested a considerable improvement of biodegradability for subsequent biological treatment. This study provided a demonstration of using microwave irradiation to enhance reaction between SA and nitrite in a short time, in which nitrite in wastewater was completely converted into nitrogen gas without leaving any sludge and secondary pollutants.展开更多
Graft copolymerization of acrylamide onto starch and reaction with mercaptoacetic acid subsequently were studied.The reaction product(St-AM-MCAA) was used in the treatment of wastewater containing low concentration ca...Graft copolymerization of acrylamide onto starch and reaction with mercaptoacetic acid subsequently were studied.The reaction product(St-AM-MCAA) was used in the treatment of wastewater containing low concentration cadmium ion(0.40 mg·L-1) as additive.An investigation was carried out to study the effect of St/AM(mass ratio of starch to acrylamide) on the grafting ratio and grafting efficiency and the content of thiol(SH) group.It was found that the cadmium ion removal percentage by St-AM-MCAA3 reached 89.7% and the residual concentration of cadmium ion in treated water was under 0.10 mg·L-1 in the conditions of pH=8 and additive concentration of 2.0 g·L-1 by selecting a high grafting ratio and thiol content product St-AM-MCAA3 as additive.The ability of St-AM-MCAA3 to remove low concentration wastewater containing cadmium ion was higher than that of St-AM3 by 10%.展开更多
基金supported by the National Natural Science Foundation of China (No.50678045)
文摘High-concentration nitrite-containing wastewater that presents extreme toxicity to human health and organisms is difficult to be treated using traditional biological process. In this study, a novel microwave-enhanced chemical reduction process （MECRP） using sulfarninic acid （SA） was proposed as a new manner to treat such type of wastewater. Based on lab-scale experiments, it was shown that 75%-80% nitrite （NO2-） could be removed within time as short as 4 min under 50 W microwave irradiation in pH range 5-10 when molar ratio of SA to nitrite （SA/NO2-） was 0.8. Pilot-scale investigations demonstrated that MECRP was able to achieve nitrite and chemical oxygen demand （COD） removal with efficiency up to 80% and 20%, respectively under operating conditions of SA concentration 80 kg/m3, SA/NO2- ratio 0.8, microwave power 3.4 kW, and stirring time 3 min. Five-day biological oxygen demand （BODs）/COD value of treated effluent after MECRP was increased from 0.05 to 0.36 （by 620%）, which clearly suggested a considerable improvement of biodegradability for subsequent biological treatment. This study provided a demonstration of using microwave irradiation to enhance reaction between SA and nitrite in a short time, in which nitrite in wastewater was completely converted into nitrogen gas without leaving any sludge and secondary pollutants.
文摘Graft copolymerization of acrylamide onto starch and reaction with mercaptoacetic acid subsequently were studied.The reaction product(St-AM-MCAA) was used in the treatment of wastewater containing low concentration cadmium ion(0.40 mg·L-1) as additive.An investigation was carried out to study the effect of St/AM(mass ratio of starch to acrylamide) on the grafting ratio and grafting efficiency and the content of thiol(SH) group.It was found that the cadmium ion removal percentage by St-AM-MCAA3 reached 89.7% and the residual concentration of cadmium ion in treated water was under 0.10 mg·L-1 in the conditions of pH=8 and additive concentration of 2.0 g·L-1 by selecting a high grafting ratio and thiol content product St-AM-MCAA3 as additive.The ability of St-AM-MCAA3 to remove low concentration wastewater containing cadmium ion was higher than that of St-AM3 by 10%.
