The Study Of The Compost Of Lanzhou Municipal Sewage Sludge

This research emphasizes on four kinds of composting. The first method is adding wheatstraw, corn straw and leaves on urban sewage sludge proportionally for conducting the hightemperature aerobic composting experiment. The second way is mixing dry urban sewagesludge and fresh one with different proportion for conducting high temperature aerobiccomposting experiment. In the third method, corn straw, dry urban sewage sludge and themicrobial bacteria agents are mixed proportionally for high temperature aerobic compostingexperiment. The forth method way is comparing ventilntion with no ventilntion. These studiesstudy the effect of the three different ways on the composting of sewage sludge in Lanzhou,and provide the basis for resource utilization of municipal sludge in Lanzhou. Results are asfollows,1. All three studies of composting can make the urban life sewage sludge reach maturityin natural stacking condition. Adding microbial agents make the pile begin to warm upquickly in the first3d days, and keep the situation of high temperature with longer period.Then The corresponding cooling period is short, so the cycle of composting is shorter. Thetime of keeping the temperature above the50℃is equivalent for choice of corn-wheat strawand dry sludge, however the previous one reaches the50℃in advance. The composting ofadding microbes has the most significant effect on temperature, adding2.5%corn straw and2.5%wheat straw has the less significant effect, then adding dry sludge has the minimalimpact.2. The three studies of composting can cause the water content of composting to decreaseto the degree which is lower than45%, which can achieve the requirements of using sludgecomposting on landscaping. Adding microbes has the most significant effect on water content,the medium effect is adding the dried sludge treatment, the least effect is adding corn strawand wheat straw as materials processing.3. Adding dried sludge, corn straw and wheat straw or fresh sludge can all reduce the allnitrogen loss. The best way of protecting nitrogen is adding corn straw and wheat straw, theInferior way is to adding the dried sludge treatment, the worst one is adding corn straw andwheat straw. Adding microbial agents is not conducive to the nitrogen accumulation, causesnitrogen loss.4. Adding dried sludge, corn straw and wheat straw or fresh sludge can promote thedegradation of organic matter. Adding microbes has the most significant effect on reduction ofsludge, the medium effect is adding the adding corn straw and wheat straw treatment, the Least effect is adding the dried sludge treatment.adding corn straw and wheat straw asmaterials processing.5. Lanzhou urban sludge C/N is6.5,.When adding5%corn straw and wheat straw,it canmake the C/N increase to7~10, but still belongs to the lower C/N sludge compost. Eachcomposting T is closest near to0.6when Adding microbial agents and maturity is highest.Adding the corn straw and wheat straw is higher than adding the dried sludge is relativelylow.6. The three studies of composting can make the content of available phosphorusIncreasing. The largest amplitude of available phosphorus increasing is adding corn and wheatstraw, the larger is adding the microbial agents, then the large is adding the dried sludge.7. The three studies of composting can make the conte nt of available potassiumincreasing. The increasing amplitude of the content of available potassium is not obviousbetween the addition of the dried sludge and microbial agents, but the increasing amplitude isrelatively higher by adding corn and wheat straw.8. Adding microbes have the most significant effect on C/N, it needs the medium effect isadding the dried sludge treatment, the Least effect is adding corn straw and wheat straw asmaterials processing. The three studies of composting can cause the C/N of composting todecrease to the degree which is lower than S during composting10days,19days and48days.9.S+30%DS,S+5%W,S+5%C and S+40%DS+5%C+0.2%A after the composting hasinhibitory substance on germination basically eliminated, the toxicity of corrosion products onthe plants is weak and basically non-toxic; pea seeds are sensitive to various treatments, rapeseeds show a greater resistance. The experiment can be conducted through selection of peaseeds, as a non-hazardous biological index of the four composting way.10. IfWe don’t conduct stack ventilationtreatments, No matter adding the crop straw ormicrobial agents cannot make the treatments up to50℃; If the sludge height is1.2m, whichreduces the heating rate of sludge, but after the temperature up to50℃, The treatment withlarge size has the character with extension of the time in the high temperature.In summary, in the natural state, fresh sludge processing doesn’t reach the standard ofcompost, however, adding corn straw, wheat straw, the dried sludge and microbial agentshave effects on temperature, moisture content, nitrogen, phosphorus and potassium elements,and the effects are different. They all have pros and cons. We can choose the proper way ofsludge composting according to the final requirements of sludge processing.