ABSTRACT
A sewage treatment plant consists of multiple treatment systems, such as preliminary, primary, secondary, and tertiary treatment. In the process of treating wastewater, each of these treatment phases plays an important part. The many treatment units that are a part of primary treatment are the topic of discussion in this chapter. When wastewater enters a sewage treatment plant, the first step of treatment is called primary treatment. Screens, grit chambers, and sedimentation are the most frequently used treatment units. Wastewater contains rags, sticks, and heavy inorganic grit, which may cause maintenance and operational problems. They are removed in the screens and grit chamber. After screening and grit removal, the primary constituents of the wastewater are organic and inorganic suspended and dissolved matter. The primary sedimentation tank is used to remove inorganic and organic suspended solids. They help to reduce the organic load of the secondary treatment units. In this chapter, the fundamental concepts of primary treatment units and their design have been described in detail.
