粉煤灰对污水处理的效果及其环境影响试验研究

循环流化床燃烧产生的粉煤灰按不同比例与污水充分混合,其对污水中P的去除率可达90%以上;对COD的去除率为45%左右;对NH3-N的去除效果较差,最高不超过11%。由于粉煤灰含有大量钙,可以与粉煤灰中的磷酸盐形成沉淀,故采用循环流化床产生的粉煤灰可以有效处理含P较高的污水。文章研究了粉煤灰中重金属在污染水中释放规律,如Pb、Cd、Cu、Cr及Ni等,由于粉煤灰与污水浸泡后pH值呈碱性,且污水中含有大量有机物质,使反应体系呈还原状态。因此,粉煤灰中的重金属可以稳定存在,粉煤灰在污水中几乎不释放重金属,所以未加任何处理的粉煤灰在浸泡过程中不会对环境产生重金属污染。为此,粉煤灰可用于井下采空区回填,也可用于路基填充等。由于粉煤灰中少量碱性物质溶于水中,可使地下水pH值升高。

Experimental study on coal ash for treating wastewater and its influences to environment

Coal ash from circulation fluidized burning is chosen to mix with wastewater at different proportion. The treating results such as COD, P and NH3-N in wastewater are analyzed. Over 90 percent of phosphor can be removed from wastewater. 45 % of COD can also be wiped off at the same time. NH3-N cannot be removed effectively by the coal ash and no more than 10 percent of it can be removed. Therefore, wastewater with high concentration of phosphor. Because coal ash from circulation fluidized burning can be used to treat some calcium exists in ash, phosphor can sink at the form of calcium phosphate at the surface of ash. The releasing law of heavy metals, such as Pb, Cd, Cu, Cr and Ni in wastewater is also studied in experiment. The wastewater is alkalescence after blending with ash. Reaction system in wastewater shows reducation condition because of mass organic matter. Heavy metals can exist in ash stably. Coal ash without any treatment does not contaminate environment when the ash is used to refill the goaf in coalmines. The ash can also be used for roadbed, pH in groundwater can rise as a result of alkalescence matter from coal ash melting in water.