Sludge is different from other solid wastes in that it has the following main characteristics:
1. The water content is high, as much as 70% or more. This part of the water is difficult to burn, transportation costs are high, and the stacking area is large. Direct landfill will cause the landfill to be scrapped in advance.
2. The content of microorganisms and pathogens is high. If it is directly applied or discarded without treatment, it may contaminate the food chain.
3. The stench pollutes the environment and emits greenhouse gases into the atmosphere (20 times that of carbon dioxide).
4. Ultra-fine powder, there is a greater danger during thermal drying and processing.
5. Containing heavy metals, if not controlled application, it may pollute the land and cause irreversible degradation of cultivated land;
At present, the harm of sludge is still unknown, and it is often taken illegally, causing excessive accumulation of heavy metals in the land, soil compaction, and inadvertent pollution and destruction of human living environment and food. The European Community classifies sewage plants and waterworks sludge as "special garbage" (not "hazardous garbage"), which must be properly handled by qualified companies in accordance with prescribed procedures and must not be disposed of.
ccount the nitrifying bacteria.