Is sewage sludge simply treated by drying, incinerating, or landfilling?
Sewage sludge is a microbial mass. Each microbe has cells, and each microbe cell is covered in a strong cell wall (cell membrane). The ability to break down these cell walls becomes a crucial point for effective sludge treatment. Conventional methods such as strong acid/alkali, high temperature and pressure, or ozone treatment do not break microbe cells effectively. Therefore, the conventional dewatering process tends to simply use a dewater device. Cell cytoplasm isn’t release just by spin-drying without breaking cell walls. This is like pressing down a soft balloon; balloon rubber just stretches out, but the barrier remains intact. This simple dewatering process is likely to cut down only about 20% of the excess sludge’s water content.
What if we incinerate or landfill such high water content material? The impact to the surrounding environment can be enormous. In China, any final disposal must meet a requirement of reduction down to 60% or less. However, with current technologies, there is no such device to reduce water content below 60%.
This explains how important and urgent the issue of sludge treatment is. Organizations and groups around the world have been working toward solutions, but a breakthrough technology is not yet available.
WEF Institute of Technology Inc.
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