电絮凝法处理纺织废水研究

A renovated method on treating textile industrial sewage via electrocoagulation

为了考察铁、铝电极电絮凝法处理纺织废水的效果和影响因素,以铁板和铝板为电极对纺织废水进行了电絮凝处理,考察了初始pH值、电流密度、电絮凝时间对COD去除率、色度去除率、电能消耗及电极损失的影响。结果表明:初始pH值为7时,铁、铝电极电絮凝后最终pH值均有上升,但均未超过8,无需调节pH值;随电流密度增加,COD去除率、色度去除率、电能消耗及电极损失呈上升趋势,电流密度为7.5 mA/cm2时,铁电极的COD去除率可达72%,色度去除率可达89.1%,高于铝电极;电絮凝时间为15 min时,铁电极的COD去除率可达到76%,色度去除度可达90%,高于铝电极,且电能消耗低于铝电极。研究表明,铁电极电絮凝法处理纺织废水具有技术可行性,最佳试验条件为:初始pH值中性,电流密度7.5 mA/cm2,电絮凝时间15 min。

This paper intends to report a renovated method developed by its authors on treating the textile industrial sewage via electrocoagulation. The renovated method is founded on the use of the iron and aluminum electrodes to treat the textile sewage from the textile dyeing factories by way of electrocoagulation to heighten the COD removal efficiency, the chroma removal efficiency, by overcoming the influential factors and applying the best available processing parameters of the said textile sewage. As is known, the initial COD, the chroma and the pH value of the textile sewage referred to as in this paper account for 3 000 mg/L, 500 and 7, respectively. In order to work out the improved method, we have done an investigation of the effects of the initial pH value, the current density, the electrocoagulation time on the removal rate of COD, so as to raise the removal rate of chroma, and reduce the power consumption and electrodes consumption in this paper. The results of our investigation and experiments have shown that, with the condition of initial pH value being 7, it can be expected to increase the final pH value by no more than 8 after electrocoagulation by means of applying the iron and aluminum electrodes. Thus, it can be seen that it would be impossible to adjust the pH value. However, with the increase of the current density, the removal rate of COD, the removal rate of chroma, the power consumption, electrodes consumption tend to increase correspondingly. When the current density is 7.5 mA/cm^2 , the COD removal rate of the iron electrodes can be expected to reach 72%, whereas the chroma removal rate of the iron electrodes can be expected to reach 89.1%, all being higher than those of the aluminum electrodes. When the electrocoagulation time increased to 15 min, the COD removal rate of the iron electrodes can be expected to reach 76%, whereas the chroma removal rate of the iron electrodes is supposed to reach 90%, thus, turning to be all higher than that of the aluminum electrodes. However, if the electrocoagulation time lasts was less than 10 min, the power consumption of iron electrodes tends to be lower than that of the aluminum electrodes. Thus, from the analysis of experimental results it can be concluded that the above said iron electrodes electrocoagulation method we have developed for treating the textile sewage proves technically feasible. The optimalized processing parameters from the tests can be shown as follows： with the use of the iron electrodes, the initial pH value should be neutral, with the current density of 7.5 mA/cm^2 , and the electrocoagulation time of 15 min.