The optimized leaching techniques were studied by technical experiment and neural network optimization for improving indium leaching rate. Firstly, effect of single technical parameter on leaching rate was investigate...The optimized leaching techniques were studied by technical experiment and neural network optimization for improving indium leaching rate. Firstly, effect of single technical parameter on leaching rate was investigated experimentally with other parameters fixed as constants. The results show that increasing residual acidity can improve leaching rate of indium. Increasing the oxidant content can obviously increase leaching rate but the further addition of oxidant could not improve the leaching rate. The enhancement of temperature can improve the leaching rate while the further enhancement of temperature decreases it. Extension leaching time can improve the leaching rate. On this basis, a BPNN model was established to study the effects of multi-parameters on leaching rate. The results show that the relative error is extremely small, thus the BPNN model has a high prediction precision. At last, optimized technical parameters which can yield high leaching rate of 99.5%were obtained by experimental and BPNN studies：residual acidity 50-60 g/L, oxidant addition content 10%, leaching temperature 70 ℃ and leaching time 2 h.展开更多
To improve the efficiency of petrochemical wastewater purification, the relationship between bacterial community structure and pollutants loading/degrading rates in A/O process for petrochemical wastewater treatment w...To improve the efficiency of petrochemical wastewater purification, the relationship between bacterial community structure and pollutants loading/degrading rates in A/O process for petrochemical wastewater treatment was investigated by denaturing gradient gel eleetrophoresis （DGGE） of the 16S rRNA gene fragments amplified by polymerase chain reaction （PCR）. Results show that while the influent COD and NH4^＋ -N concentrations are 425.92 -560 mg/L and 64 - 100 mg/L respectively, the corresponding average concentrations of the effluent are 160 mg/L and 55 mg/L, which are 1. 6 and 3.6 times more than the national standards respectively. It demonstrates that the performance of pollutants removal process is inefficient. The analysis of PCR-DGGE profile indicates that the bacterial community structure of the activated sludge in A/O system is species-rich but unstable, and the highest and the lowest similarity coefficients are 36% and 6. 25% respectively, which shows that remarkable community structure evolution exists in the system. The variation of bacterial community structure and pollutants loading influences the removal efficiency of pollutants obviously, and relatively stable com- munity structure leads to the stable operational performance of biological wastewater treatment system.展开更多
[Objective] The aim was to obtain higher COD removal rate so as to guide the process of citric acid industrial wastewater. [Method] The effects of controllable factors, acidification time, hydraulic retention time, an...[Objective] The aim was to obtain higher COD removal rate so as to guide the process of citric acid industrial wastewater. [Method] The effects of controllable factors, acidification time, hydraulic retention time, and influent COD concentration, in-anaerobic treatment process of citric acid wastewater on COD removal rate were studied and the COD removal rate was optimized by response surface method. [Result] There was no interaction between acidification time and the other two factors. It was showed that hydraulic retention time and influent COD concentration had significant effect on COD removal rate and there was interaction between the two factors. The optimum COD removing process conditions was as follows: acidification time 1.53 h, hydraulic retention time 3.52 h and influent COD concentration 2 698 mg/L. Under the optimized conditions, the COD removal rate was 93.31% and it was much closed to the experimental result, 93.29%. [Conclusion] Using response surface method to optimize the anaerobic treatment of citric acid wastewater can result in optimized achievement.展开更多
基金Project(2012BAE06B01)supported by the National Key Technologies R&D Program of China
文摘The optimized leaching techniques were studied by technical experiment and neural network optimization for improving indium leaching rate. Firstly, effect of single technical parameter on leaching rate was investigated experimentally with other parameters fixed as constants. The results show that increasing residual acidity can improve leaching rate of indium. Increasing the oxidant content can obviously increase leaching rate but the further addition of oxidant could not improve the leaching rate. The enhancement of temperature can improve the leaching rate while the further enhancement of temperature decreases it. Extension leaching time can improve the leaching rate. On this basis, a BPNN model was established to study the effects of multi-parameters on leaching rate. The results show that the relative error is extremely small, thus the BPNN model has a high prediction precision. At last, optimized technical parameters which can yield high leaching rate of 99.5%were obtained by experimental and BPNN studies：residual acidity 50-60 g/L, oxidant addition content 10%, leaching temperature 70 ℃ and leaching time 2 h.
基金Sponsored by the National Basic Research and Development (973) Program of China(Grant No.2004CB185050)
文摘To improve the efficiency of petrochemical wastewater purification, the relationship between bacterial community structure and pollutants loading/degrading rates in A/O process for petrochemical wastewater treatment was investigated by denaturing gradient gel eleetrophoresis （DGGE） of the 16S rRNA gene fragments amplified by polymerase chain reaction （PCR）. Results show that while the influent COD and NH4^＋ -N concentrations are 425.92 -560 mg/L and 64 - 100 mg/L respectively, the corresponding average concentrations of the effluent are 160 mg/L and 55 mg/L, which are 1. 6 and 3.6 times more than the national standards respectively. It demonstrates that the performance of pollutants removal process is inefficient. The analysis of PCR-DGGE profile indicates that the bacterial community structure of the activated sludge in A/O system is species-rich but unstable, and the highest and the lowest similarity coefficients are 36% and 6. 25% respectively, which shows that remarkable community structure evolution exists in the system. The variation of bacterial community structure and pollutants loading influences the removal efficiency of pollutants obviously, and relatively stable com- munity structure leads to the stable operational performance of biological wastewater treatment system.
文摘[Objective] The aim was to obtain higher COD removal rate so as to guide the process of citric acid industrial wastewater. [Method] The effects of controllable factors, acidification time, hydraulic retention time, and influent COD concentration, in-anaerobic treatment process of citric acid wastewater on COD removal rate were studied and the COD removal rate was optimized by response surface method. [Result] There was no interaction between acidification time and the other two factors. It was showed that hydraulic retention time and influent COD concentration had significant effect on COD removal rate and there was interaction between the two factors. The optimum COD removing process conditions was as follows: acidification time 1.53 h, hydraulic retention time 3.52 h and influent COD concentration 2 698 mg/L. Under the optimized conditions, the COD removal rate was 93.31% and it was much closed to the experimental result, 93.29%. [Conclusion] Using response surface method to optimize the anaerobic treatment of citric acid wastewater can result in optimized achievement.
