Question

What is the cost-benefit relationship regarding sewage treatment as a strategy to fight water pollution?

Answer 1

The non-treated sewage can pollute the rivers, ponds and the sea. After pollution, rivers, ponds and sea usually contain pathogens of some disease. It is much cheaper to treat the sewage and keep the water reservoirs (rivers, ponds, sea etc) pollution free. For any population, diseases have much higher cost in comparison with the sewage treatment.

One of the most fruitful and economically beneficial steps of sewage treatment is aerobic treatment. In this process, water reservoirs contain much oxygen for aerobic bacteria as they can decompose the organic material of the sewage.