PRB修复垃圾渗滤液污染地下水过程中pH值变化分析

Analysis of pH Value During In-situ Remediation of Leachate-polluted Groundwater with PRB Technique

随着城市化的不断发展,生活垃圾产生量越来越多,因管理不善,导致垃圾渗滤液污染地下水的问题越来越突出,污染地下水的修复研究迫在眉睫。实验模拟地下环境,以被垃圾渗滤液污染地下水为研究对象,分别用沸石、无烟煤、陶粒、活性炭、炉渣、粉煤灰、零价铁作为反应介质,设计了6种地下可渗透反应墙(PRB),分别为反应器1、2、3、4、5和6。分3个阶段对PRB技术治理污染地下水中pH值影响和变化进行模拟研究,分析反应器pH值降低的原因并探讨pH值变化机理。实验结果表明,所有反应器pH值较进口降低,第三阶段出口pH值平均值较进口平均降低0.40;因水解酸化反应存在,产生一定量NH4+和有机酸,造成反应器出水pH值降低和复合填充材料NH4+相对去除率降低,说明PRB技术治理渗滤液污染地下水具有一定可行性,但技术方法有待继续深入研究。

With the continuous development of urbanization, generation of leachate from more and more domestic garbage led to groundwater pollution increasingly significant. So it became more and more extremely urgent to do research on remediation of polluted groundwater. With the purpose of simulating groundwater environment and studying the feasibility and the efficiency of the permeable reactive barrier（PRB） technique in the remediation of leachate-polluted groundwater, six kinds of reaction media, including zeolite, anthracite, ceramisite, activated carbon, slag, flyash and zero valent iron（ZVI）, were used to design six styles of PRB, viz. reactors 1, 2, 3, 4, 5 and 6 respectively. Simulated experiment was conducted through three periods to research influence factors on pH value in sewage treatment by PRB. It was analyzed why pH value was decreased, and the change mechanism of pH was discussed. The experiment results indicated that pH values in all reactors were lower than that in the inlet, and the average value of pH in the outlet of the third period was 0.40 lower than that in the inlet; and that generation of NH＋4 and organic acid, due to the process of hydrolysis reaction,led to the decrease of both pH and relative removal ratio of NH＋4 by composite filling materials. It was difficult to reflect objectively the practical treatment capacity of every filling material by these consequences. So in the treatment of leachate-polluted groundwater, application of PRB technique was feasible to a certain extent, but further research was expected.