电动力技术除去污泥中重金属的试验研究
发布时间:2018-05-30 02:48
本文选题:污泥 + 电解 ; 参考:《中国矿业大学》2015年硕士论文
【摘要】:剩余污泥的土地利用是目前处理处置污泥的方法中最适合中国国情的一种方法。剩余污泥在土地利用中,本身含有的有毒重金属会对土壤,地下水造成二次污染,通过食物链则会对动植物造成伤害,另一方面污泥中含有大量的矿物元素(氮,磷,钾等)和有机物,这些矿物元素和有机物可以使土壤有肥力,农作物多产。所以去除剩余污泥中的重金属就变得十分有意义。本实验以徐州国祯污水处理厂的剩余污泥为研究对象,在不同的电解质,阴极液种类,阴极液p H,电压梯度,电解时间的条件下,测定实验过程中电流的大小及变化,p H值大小,各区域金属含量,金属去除率以确定实验的最优条件。实验显示,实验过程中的电流变化趋势都是实验一开始迅速升高,达到峰值,然后缓慢下降至于稳定,p H值从阳极向阴极逐渐增大,电解结束后金属Cu富集在阴极附近,Cr(Ⅵ)在阳极附近富集。在其他条件相同的情况下,添加电解质为磷酸二氢钾时,金属的去除率最高,Cu的平均去除率为84.80%,总Cr的去除率为38.80%,Cr(Ⅵ)的去除率为90.86%,阴极液添加缓冲液为醋酸,且维持阴极液的p H为7.5时,金属的去除率最高,Cu的平均去除率为77.15%.,总Cr的去除率为50.80%。电压梯度为2V/cm时,金属的去除率最高,Cu的平均去除率为83.60%,总Cr的去除率为60.94%。电解时间为60小时,金属的去除率最高,Cu的平均去除率为83.60%,总Cr的去除率为60.94%。由此得出最优电解条件为添加电解液为KH2PO4,阴极加入醋酸-醋酸钠缓冲液,维持p H值为7.5,电压梯度为2V/cm,通电时间为60h时。由实验中测的p H值的变化得出,越靠近阳极的区域,p H越低,有利于金属的解析,然后对实验进行了改进,电解30h后移动阳极,缩短阴极和阳极之间的距离,保持电解液,阴极液种类和p H值,电压梯度不变,再电解30h,结果表明Cu的去除率与固定阳极时提高了10%,Zn的去除率提高了24%。由实验得出,在一定范围内,随着施加的电压梯度越大,金属的去除率越高,但是电压梯度过大,容易发生极化现象,氢析出电压反应了产生极化现象时的电压大小,在阴极液中添加有机物庚烷和环己烷后,氢析出电压发生了改变,从1.42v/cm变为0.667v/cm,以Zn的去除率为例,加入有机物电解,去除率由60.94㳠上升到83.70㳠。调节试验过程中的电压,使阴极上始终不产生气泡(即不产生极化现象)的变压条件下实验也可以减轻极化现象,金属Cu的去除率从83.6%提高到89.78%。金属Zn的去除率从60.94%提高到75.36%。
[Abstract]:Land use of excess sludge is one of the most suitable methods for sludge disposal in China. In land use, excess sludge contains toxic heavy metals that cause secondary pollution to soil and groundwater, and damage to plants and animals through the food chain. On the other hand, sludge contains a large amount of mineral elements (nitrogen, phosphorus, phosphorus). Potassium and organic matter, these mineral elements and organic matter can make the soil fertility, crop production. Therefore, the removal of heavy metals in excess sludge becomes very meaningful. In this experiment, the excess sludge of Xuzhou Guozhen sewage treatment Plant was studied under the conditions of different electrolytes, kinds of cathodic solution, cathodic solution pH, voltage gradient, electrolysis time, etc. In order to determine the optimum conditions of the experiment, the magnitude of current and the variation of pH value, the metal content in each region and the metal removal rate were measured in order to determine the optimum conditions of the experiment. The experimental results show that the current variation trend in the experimental process is that the current increases rapidly and reaches the peak value at the beginning of the experiment, and then decreases slowly and the steady pH value increases gradually from the anode to the cathode. After electrolysis the metal Cu is enriched near the cathode and the Cr (鈪,
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