SBR活性污泥系统对废水中Cu^(2+)去除研究

Study on removal of Cu^(2+)from wastewater by SBR activated sludge system

为探究活性污泥法处理含铜废水的可行性,以活性污泥和模拟含铜废水为研究对象,开展了静态吸附和SBR系统动态去除试验,分别研究了Cu^(2+)静态吸附效果、影响因素、吸附模型和吸附机理,以及Cu^(2+)动态处理效果和系统变化。结果显示,活性污泥静态吸附Cu^(2+)的适宜pH值为4~7,25℃下最大吸附量为41.13 mg/g;准二级动力学模型和Langmuir模型对吸附过程拟合较好,吸附机理主要包括表面有机络合、离子交换和静电吸附;SBR活性污泥系统对不同质量浓度(3 mg/L、5 mg/L、10 mg/L)Cu^(2+)的去除率分别为95%~98.7%、67.8%~76.2%、72.9%~82.4%,化学需氧量(Chemical Oxygen Demand,COD)去除率稳定在90%以上,系统中污泥浓度(Mixed Liquid Suspended Solids,MLSS)和污泥体积指数(Sludge Volume Index,SVI)明显下降;在Cu^(2+)长期作用下,活性污泥系统性能呈现先波动后稳定的趋势,微生物种群结构趋向于单一化。

In order to explore the feasibility of treating copper-containing wastewater by activated sludge process,we took activated sludge and simulated copper-containing wastewater as research objects,and carried out a static adsorption and SBR system dynamic removal experiment.In the static adsorption experiment,the effects of influencing factors on adsorption efficiency were studied,including pH,sludge concentration,adsorption time,initial Cu^(2+)concentration and temperature.Besides,the kinetic model,adsorption isothermal model and mechanism of static adsorption of Cu^(2+)by activated sludge were analyzed.In SBR activated system dynamic removal experiment,treatment efficiency and changes of activated sludge characteristics were studied,including removal efficiency of Cu^(2+)and COD,mixed liquid suspended solids,and sludge volume index.In addition,we analyzed the differences of microbial community structure in activated sludge before and after the action of Cu^(2+).Experimental results show that the suitable pH range of Cu^(2+)adsorption by activated sludge is 4-7.The maximum adsorption capacity is 41.13 mg/g at 25℃,and the increase or decrease of temperature will lead to the decrease of adsorption capacity.The pseudo-second-order kinetic model and Langmuir model fit the adsorption process well,which illustrates that the main adsorption forms are chemical adsorption and monolayer adsorption.The adsorption mechanism mainly includes surface organic complexation,ion exchange and electrostatic adsorption.The removal rates of different mass concentrations of Cu^(2+)(3 mg/L,5 mg/L and 10 mg/L)by SBR activated sludge system were 95%-98.7%,67.8%-76.2%and 72.9%-82.4%respectively.The removal rate of COD could reach more than 90%,and MLSS and SVI decreased significantly in the presence of Cu^(2+).Under the long-term action of Cu^(2+),the performance of the activated sludge system fluctuated first and then stabilized,and the microbial community structure tended to be simple.In general,SBR activated sludge system has achieved good removal efficiency of Cu^(2+),and the research results are of certain reference value for the practical treatment of copper-containing wastewater.