污染河流中Cr(Ⅵ)对浅层地下水的影响研究

Influence on shallow ground water by chromium in polluted river

为了研究污染河流中Cr(Ⅵ)对浅层地下水的影响,选用3种天然砂土作为渗透介质进行室内试验,以生活污水模拟污染河水,发现铬在粗砂中第13d发生穿透,此后粗砂对铬的去除率为77%～99%;2种中砂对铬的去除率始终大于91%和96%,铬很难进入地下水。凉水河野外试验表明,凉水河沿岸的1#、2#、3#采样点和煤厂井中Cr(Ⅵ)浓度均不大于地下水中Cr(Ⅵ)的背景浓度,凉水河中的Cr(Ⅵ)对地下水影响较小.还原和沉淀反应是Cr(Ⅵ)去除的主要机理,由于长期污染河流下部渗透介质始终处于厌氧环境,其中富含还原性物质,Cr(Ⅵ)可以通过沉淀反应大部分得以去除,本次试验研究表明污染河流不是地下水铬污染的来源.

In order to study the influence on shallow ground water by Cr（Ⅵ） in polluted fiver, in the lab-scale experiment three kinds of natural sand were chosen as infiltration medium, and polluted rivers were simulated by domestic sewage, it was found that Cr（ Ⅵ ） penetrated on the 13th day and then had a removal ratio of 77% - 99% in coarse sand, over 91% and 96% in two kinds of medium sand. It was difficult for Cr（ Ⅵ ） to enter ground water. In on-site test it was indicated that the concentration of Cr（ Ⅵ ） in 1 # ,2# ,# Sand coal yard well along the bank of Liangshni River was not greater than background concentration in groundwater, so Cr（ Ⅵ ） in Liangshui River had a little influence on ground water. The mechanism of Cr（ Ⅵ ） removal was reducing action and sedimentation. Cr （ Ⅵ ） mainly was transformed to precipitation by reducing action because of abundant reduction agent in the infiltration media, so the tests indicated that polluted river was not the source of Cr（ Ⅵ ） pollution in ground water.