草鱼养殖模拟废水正渗透处理工艺参数优化及膜污染特征研究

Research on key process parameters and membrane pollutant characteristics of forward osmosis treating simulated grass carp farming wastewater

选用蔗糖溶液作为汲取液,草鱼养殖模拟废水为原料液,采用响应面法研究不同汲取液浓度、错流过滤流速和汲取液温度下,正渗透系统原料液COD浓度和平均水通量的变化,研究汲取液浓度、错流过滤流速和汲取液温度相互作用,确定了最优工艺参数,并在最优工艺条件下考察正渗透膜污染特性.结果表明,汲取液浓度和错流过滤流速对系统运行效果影响较大,温度影响次之,正渗透处理草鱼养殖模拟废水最优工艺参数组合为汲取液浓度2mol/L,错流过滤流速18.7cm/s,汲取液温度33.6℃,在此条件下草鱼模拟养殖废水COD浓度变化倍数为2.9,平均水通量为27.4L/(m^(2)·h).正渗透膜表面污染物以蛋白质等有机污染物为主,还有少量的无机盐类物质.

In this study,sucrose solution was used as the draw solution of the forward osmosis system,and the simulated grass carp farming wastewater was used as the feed solution.By using the response surface method,the COD concentration of the feed solution and the average water flux of the system were investigated under different concentrations of draw solution,the flow rate of the cross-flow filtration and temperature of draw solution,consequently,the optimal parameters combination for the maximal values of COD concentration and the average water flux was determined.In addition,the membrane fouling in the forward osmosis system was characterized in this study.Results show that the concentration of the draw solution,the flow rate of the cross-flow filtration and the temperature of the draw solution had significant impacts on the COD concentration of the feed solution and the average water flux of the system,respectively.The concentration of the draw solution and the flow rate of the cross-flow filtration had greater impacts on the forward osmosis system,than the temperature of the draw solution did.The optimal combination of process parameters is as follows:the concentration of the draw solution is 2mol/L,the flow rate of cross-flow filtration is 18.7cm/s,and the temperature of the draw solution is 33.6℃.Under the forementioned optimal combination of process parameters conditions,the COD concentration multiple of the simulated wastewater is 2.9and the average water flux is 27.4L/(m^(2)·h).The characterization of membrane fouling demonstrated that the pollutants attached on the membrane are mainly organic pollutants such as proteins,and inorganic salts are also detected.