Experimental Study On The Treatment Of Soil Cr(?) Pollution By Residual Activated Sludge

In recent years,the world economy has been advancing by leaps and bounds.Compared with the past,Chinese economy has taken on a new look.However,with the development,the irrational behavior in the process of mining and smelting heavy metals and the use of heavy metal pesticides have caused serious pollution to the soil.Many scholars have paid close attention to the problem.In this paper,the residual activated sludge conditioner,through which the pH and Eh of soil will change and soil micro environment will be improved.Then by changing the metal valence,precipitation of heavy metals in soil is increased.soil available heavy metals is reduced.As a result,with the nature of the soil structure is changed,reducing the heavy metal leaching toxicity is reduced.In general,in order to select better soil amendments and find better soil environment needed for amendments,4comparative respects are analyzed.Firstly,the drying sludge(WAS1),humic acid(HA)and fresh sludge(WAS2)are used as organic modifier,and the effects of three improved fertility are compared and analyzed.Secondly,the drying sludge(WAS1),humic acid(HA)and fresh sludge(WAS2)were used as organic modifier,and the effects of three treatment effect of soil chromium pollution are compared and analyzed.Thirdly,with Fe(II)as reducing agent,the improvement effect of 0mol Fe(II),0.5molFe(II)and 1.0molFe(II)with drying sludge(WAS1)in soil chromium pollution are compared.Fourthly,different levels of dried sludge(WAS1)for soil chromium pollution effect,in aerobic and anaerobic environment are analyzed.Specific analysis index: soil PE value(pH,Eh),the leaching toxicity of soil liquid soil leaching solution of Cr(VI),Total Cr,Cr(III)),soil Cr(VI),Cr(III).The results show that the best effect of improving the soil acidity and improving soil fertility is fresh activated sludge,followed by drying sludge,and the effect is not obvious is humic acid,namely WAS2>WAS1>HA.In removing soil Cr(VI)and improving the toxicity of soil leach,the best effect is fresh activated sludge,followed by dry activated sludge,namely WAS2 > WAS1 > HA.At the same time,the residual activated sludge(WAS)was more effective than humic acid(HA).Under the participation of Fe(II),the concentration of Cr(VI)in soil solution has better treatment effect than that without auxiliary reducing agent,and 1.0mol>0.5mol is also concerned with Fe(II)input.In the two aspects of improvement of Cr(VI),the aerobic condition is better than anaerobic condition,namely aerobic sludge >anaerobic sludge.In addition to the level of WAS and HA,the higher the level of soil pH and Eh are,the better the toxicity of soil leaching solution and the removal of Cr(VI)from soil is.