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Question
Explain how sludge is treated.
Solution
- In the clarifier (or sedimentation tank), sludge settles at the bottom and is collected using a scraper. It is then moved to a separate tank known as the digester, where it is digested by anaerobic microorganisms.
- The biogas created during the process can be utilized for fuel or to generate electricity. The clarified water from the sedimentation tank is pumped into the aeration tank. In the aeration tank, suspended microorganisms sink to the bottom as activated sludge.
- The activated sludge is approximately 97% water. Water is removed using sand-drying beds or machinery. Dried sludge is utilized as manure, reintroducing organic matter and nutrients into the soil.
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