Study On The Reutilization Of Municipal Sewage Sludge

For a long time, the disposal of municipal wastewater treatment sludge is a serious problem of environmental protection. If a large number of sludge generated dispose improperly, it will lead to secondary pollution There are many problems in traditional treatment ways, so it is very urgent to find a good new approach for sludge treatment and disposal.This paper has analyzied the main chemical constituents, element content, heavy metals content of sludge,PFA and clay, condersidering raw material chemical composition and haydite raw material chemical composition request, it is designed to use sludge, PFA and clay as haydite raw materials. Heavy metal content and the leaching concentration of the sludge are not high. However, there are some potential harm.Aiming to the existing problems, the formula of haydite with coal fly ash and sewage sludge based on formula uniform restricted design theory was designed, then used the trefoil rotary kiln to make a test. This paper also studied the relationship between the ratio of haydite composition ingredients and loose bulk density, pellet strength regression equations were obtained by analyzing the test results, the optimal percentage of the dry quality is: fly ash/sludge/clay= 79%, 15.2%, 5.8%, haydite uses 45% dewatered sludge in wet percentage, 15.2% in dry percentage, sludge obvious reduction. Determined by orthogonal experiment find optimum conditions to produce haydite.At the optimal percentage and optimum conditions, the haydites were bured. The results show that bulk density is 600kg/m3, cylinder compressive strength is 2.2MPa, 1hr water absorption is 10.2%, grain shape coefficient is 1.3. Performances all meet the quality requirements. it is effective for sludge resources. The result of haydite identification test for extraction toxicity below extraction toxicity hazardous constituents concentration limits, sludge becomes harmless.Use the self-made haydite as light aggregate configurate light aggregate concrete, adjusting water ratio, sand ratio, PFA mixture quantity, compound the intensity rank CL45, dry apparent density 1660kg/m3 concrete. The concrete can use in the industry and the civil construction, has the very good economic efficiency and wide application prospect. Benefit analysis indicated that, use sludge manufacture haydite, has good economic efficiency, environment benefit and social efficiency, it is a new way for sludge disposal and resources use.