Study On Co-composting Of Municipal Solid Waste With Sludge In Qing Dao

With the rapid development of urbanization and the increment of population, quantity of MSW (Municipal Solid Waste)increase rapidly. Composting is one of the main methods of MSW resources treatment. However,during the trial operation of Xiaojianxi Bio-treatment Plant, it was found that the composting product was of low level rotten degree,serious loss of nitrogen and phosphorus,some heavy metals exceeded. It will affect the application scope of MSW composting product. Therefore, on the basis of separate MSW composting, different proportions of MS (Municipal Sludge) were added to improve the physical-chemical properties of the composting materials. In the experiment, the technical and environmental feasibility of MSW co-composting with sludge was tested and discussed.This research contents include the following:1) Determining the mixing ratio;2) Effects of sludge amount on nitrogen transformation and loss;3) Quality evaluation of compost products;4) The plant toxicity of compost products.The main conclusions as follows:Under the MS/MSW ratio=1:6 and 1:4(wet weight ratio),two groups materials can be quickly heat up and meet the standard of GB 7959-87《Sanitary standard for the non-hazardous treatment of night soil》,then aerobic composting is feasible. Addition of sludge is beneficial to the accumulation of ammonium and nitrate content, reducing the nitrogen loss, which is helpful to reserve nitrogen.Addition of sludge is beneficial to improve the degree of stabilization.The results of heavy metals detection, morphological analysis and leaching showed that, Cd and Ni are not detected, Zn and Pb are mainly in the unstable speciation and of high environmental risk,while Cu, Cr and As are mainly in the stable speciation and of low environmental risk.The plant toxicity of co-compost product is low. The leaching solution of the compost has different effects on plant. In the appropriate ratio, the compost is beneficial to palnt growing. The compost of MSW and sludge can be used as soil regulator or fertilizer.In the appropriate ratio,it is feasible to co-composting MSW with sludge. Addition of sludge is beneficial to reserve nitrogen and increase rotten degree. The compost product is beneficial to palnt growing. It is feasible to co-composting MSW with sludge in technology and environmental risk.