Question

There are certain processes in relation to a sewage treatment. Pick up the correct set.

Answer 1

Primary treatment is the first treatment that is used to remove the particles that are suspended and floating in the sewage. It includes screening to trap the particles. The method of sedimentation is used when the particles are removed and settled by gravity. Primary treatment is usually the first stage of wastewater treatment.

Secondary treatment removes the dissolved organic matter. This is achieved by microbes which can consume and degrade the organic matter converting it to carbon dioxide, water, and energy for their own growth and reproduction. There are certain chemicals can be used which can help in concentration and sedimentation. This helps to reduce the amount of BOD of the sewage water.

The tertiary treatment process is the modification of a conventional secondary treatment plant to remove additional phosphorus and nitrogen. There is the use of precipitants and flocculants which help in the removal of the wastes.

Generally, gelatinous precipitants are used for the removal of the particles.

Activated sludge refers to floc of microorganisms that are used in the process to break down organic matter into carbon dioxide, water, and other inorganic compounds. Some microbes grow in the water forming mass or flocs and help in the clearing of the water.