Solidification Treatment Experimental Study On The Sewage Sludge Of Urban Sewage Treatment Plant

The final disposition of city sewage sludge is a difficult problem and a challenge which both domestic and abroad have to face. Domestic technology of dealing with sewage sludge is too simple. Moreover, the organics content of sewage sludge which has been discharged is very high. They are easy to get corrupt, have malodor, and they also contain parasitic ovum, pathogenic microorganism, heavy metal and many compounds. So, we can see that the composition of pollution is very complicated, especially for the dealing with heavy metal, which is very difficult to get the standard of sanitary landfill. Heavy metal usually contains the acute or chronic toxicity that can contaminate human body in many ways, which has brought out a series of serious consequence, like environment pollution, etc. So, dispose of sewage sludge problem has become an urgent task.In order to solve the problem of treatment and disposal of sludge in China, this article proposed take native soil as the chemical additive, solidification treatment sludge with the cement the mentality. And has carried out the sludge properties analytical study. The basic geotechnical engineering properties and pollutants stabilization control were assessed to solidified sludge, and the mechanical development of strength of sludge was discussed too. The main contents of the article was shown as follows:(1) Has carried on the detailed experimental analysis and the research to the sludge basic properties. And includes: sludge moisture content determination, specific gravity determination, ph value, Toc, total nitrogen, total phosphorus, loss on ignition determination, chemical constituents determination, heavy metal content, leaching toxicity determination, heat value determination. Through experimental study discovery the moisture content was still very high after sewage treatment plant dehydration, does not perform to further process very difficultly to carry on handling directly. In the sludge the heavy metal content is very high, and leaches the toxicity to surpass the national dangerous reject leaching toxicity emission standard. The direct emissions will cause the harm to the environment. In the sludge the organic content is very high. Does in the sludge the organic content to achieve about equally 40%, the calorific value achieves about 14000kJ/kg, the nitrogen and phosphorus's average content respectively achieves 15mg/g and 1.7mg/g. May use these characteristics fully in resource utilization, changing waste into valuables.(2) Has carried on the cement solidification experiment take native soil as the chemical additive to the sludge. The research discovered that throws alone adds the cement solidification intensity not to be high, and the price is expensive. Increases the ration in the solidification material native soil to be possible to enhance the solidification intensity greatly, and reduces the solidification cost. Incorporation of native soil has a peak value. Incorporation should not surpass this peak value. 7 days is the best solidification stadium. The compatibilization ratio of solidified body is the linear relationship with Incorporation of cement and native soil.(3) Carries on the orthogonal test to the sludge solidification, the research discovered that the influence solidification body compressive strength the factor primary and secondary order is: incorporation of cement→incorporation of native soil→incorporation of sludge. The overall evaluation solidification intensity, the solidification expense and the increase compare and so on questions, determine a superior sludge solidification plan finally: m(sludge): m(cement): m(native soil)= 1: 0.11: 0.27.(4) The leaching rate of zinc and lead that are common and content high in the sludge takes the heavy metal leaching ability target. Studding incorporation of native soil and the cement influences on pollutants stabilization of solidified body and macroscopically physical encapsulation influences on pollutants stabilization of solidified body. Had proven through the research that solidification treatment sludge's technology that take native soil and the cement as the solidifying agent is effective on controlling pollutant of sludge. The sludge solidification level meets the ground project nature requirements at the same time also to beable to satisfy to the pollutant stability control request.