Effects Of Different Materials Addition Ratio And Turning Ways On The Aerobic Composting Of Sewage Sludge

Sewage sludge contained large amounts of nitrogen,phosphorus,organic matter and trace elements which were necessary in many plants.And the sewage sludge was a good biological resource which can be used as a soil conditioner for agriculture and forestry. The changes of chemical parameters, such as temperature, moisture content, organic matter, pH, total nitrogen, ammonia and nitrate were studied in the composting process. With different materials ratio and the way of artificial turning,the efficiency of aerobic thermophilic composting and compost quality was studied. The research with different materials such as municipal sewage sludge with straw was to provide a theoretical basis which could stack decomposition products. The main results were showed as follows:(l)Sewage sludge mixed with different materials such as mushroom residue and straw were tested to study the aerobic composting process in natural ventilation and artificial heap. The results showed that it could reduce the volume of sludge piles significantly.The numbers of days whose temperature of the four treatments reached more than55℃were8、5、7、8d, respectively. It could satisfy the composting health standard successfully. At the end of the composting, the seed germination indexes of the four treatments were90.8%,87.2%,63.9%,60.4%.Four treatments all reached a degree of maturity. So the piles of A, B added the mushroom residue got better Maturity than the pilesof C, D.(2) The sewage sludge mixed with different materials such as mushroom residue and straw were tested to study the aerobic composting process.The results showed that the total heavy metal of the four compost productions could reach the standard of agricultural use. At the end of the composting, the nitrogen losses of A, B, C, D were15.2%,17.9%,29.2%and27.3%,respectively; the ammonium nitrogenof A, B, C, D were0.4、0.56、0.72and0.82g/kg. So the piles of A, B added mushroom residue got better maturity than the pilesof C, D. (3)The same proportion of mushroom residue and straw was adopted as composting materials. Different ways of turning were adopted. The piles of a, b were turnedas natural temperature changes; thepiles of c, d were turned as fixed frequency. The number of days whose temperature of the four treatments reached more than55℃were8、7、9、10d, respectively. It can satisfy the composting health standard successfully. At the end of the composting, the seed germination indexes of the four treatments were90.8%、63.9%、98.8%、88.9%.Four treatments reached a degree of maturity. The results showed that the total heavy metal of the four compost productions could reach the standard of agricultural use.(4)The same proportion of mushroom residue and straw was adopted as compost materials. Different ways of turning were adopted. At the end of the composting, the nitrogen losses of a, b, c, d were15.2%,29.2%,34.1%,40.8%, respectively. The piles of c, d promoted the decomposition of organic nitrogen and got larger nitrogen losses. The ammonium nitrogenof a, b, c, d was0.44,0.72,0.28and0.61g/kg.The nitrate of a, b, c, d were1.80,1.39g,2.36,1.91g/kg. On the whole, The effect of pre-composting is not obvious at a fixed frequency turning. It is more conducive to pile composting in the end.