Question

Do the byproducts of wastewater treatment plants have any commercial value? [2 MARKS]

Answer 1

Naming: 1 Mark
Reasoning out: 1 Mark

By-products of wastewater treatment are sludge and biogas.Now,sludge is produced when solids waste like faeces settle at the bottom of tank during sedimentation when this sludge is .decomposed by the anaerobic bacteria, biogas is produced.
Sludge contains nitrogen, phosphorus and organic matter and is used as agricultural manue. Biogas is low cost energy utilised by homes. Hence both have high commercial utility.