Answer: Uses of sewage after processing: (1) biogas (methane) as fuel, (2) sludge as manure/fertiliser, (3) treated water for irrigation and gardens, (4) treated water for industrial use and cleaning.
In sewage treatment, microbes break down organic matter. Anaerobic digestion of sludge gives biogas, the digested sludge is a good manure, and the cleaned water can be reused for farming, gardens, industry or flushing, or released safely into rivers.