Solution:Concept- Sewage pollution must be treated before being released into water bodies. Primary, secondary, and tertiary treatments are applied to sewage. Screening, sedimentation, and flotation are carried out during primary treatment.
By treating sewage sludge, proper solid waste management, organic farming practices, and proper agricultural land management all aid in the avoidance of soil erosion.
Microorganisms break down organic compounds via the trickling filter or by oxidizing sludge during secondary treatment. Turbidity is eliminated during tertiary treatment. Secondary therapy is a biological procedure as a result.
Hence, the correct answer is option 2.