二级污水中6种重金属在回用时的变化

CHANGES OF SIX HEAVY METALS IN THE PROCESS OF SECOND-CLASS WASTEWATER RECOVERY AND USING

研究了城市二级污水中重金属在回用时的变化情况。结果表明 ,二级污水在回用作为循环冷却水补充水的过程中 ,有 6种重金属 ,汞、铅、银、镉、铜、砷含量会发生变化 ,经过石灰处理后 ,汞升高了约 1 80倍 ,银上升了约 2 0倍 ,这种出水补充到循环冷却水系统、浓缩2 .1倍后 ,循环水中汞却了下降了 60 %左右 ,银下降了 80 %左右 ,但铜升高了 9倍 ;二级污水平均污染指数为 0 .0 4 4 ,尚不至于发生因直接回用而产生的重金属污染问题 ,经过石灰处理后 ,平均污染指数为 3.644,循环水平均污染指数为 1 .494这两种水最好不要使用在与人体直接接触的场所。

The present paper has made a series of monitoring observation over the changes of the heavy metal content in the processing of second-class sewage recovery and exploitation. The author's monitoring observation shows that the content of the six heavy metals, Hg, Pb, Ag, Cd, Cu and As, are changeable in the different stages of the processing. After being treated by lime, the content of Hg may rise about 180 times, and Ag, 20 times. After being concentrated by 2.1 times by means of water processing, the content of Hg will decrease 60 percent, and Ag, 80 percent, while Cu, increase 9 times. The average pollution index of the second-class sewage processing is 0.044. Therefore it can be concluded that their existing in the sewage is not likely to lead to heavy metal pollution. The average pollution index after the lime treatment is 3.644 while that after the concentration is 1.494.