The Study Of Making Compound Fertilizer From Municipal Sewage Sludge

Sewage sludge has a high content of nitrogen, phosphor, kalium and many trace elements. At the same time, it also has some injurants in it, such as organic substances that are difficult to digest, heavy metals and microbes that cause diseases. So if it is not disposed appropriately, there will be a serious waste of resource in company with environmental pollution. Because routine disposal ways such as burying and burn may cause pollution and cost a lot of money, they can't be used in China. In this paper, the author has studied the possibility of making compound fertilizer from sewage sludge. First, some additives such as coal ash, sawdust and composting are added to the sludge to adjust indexes such as water ratio, volatile content, C/N, and so on. Then through main ferment (10 days) and secondary ferment (20 days) the mixture material is converted to composting product. In the end, by adding some inorganic fertilizers to the composting, we can gain qualitative compound fertilizer. The adding ratio is composting: carbamide: calcium superphosphate: potassium chloride=1:0.31:0.28:0.15.