Wastewater collection is necessary to the health of a society. This process transports wastewater from where it is generated to where it is treated. Manholes are collection points for sewage and storm water and are gravity operated. PVC, ABS, cast iron, galvanized metal, and concrete are some of the materials used for pipes and manholes. Each material has an advantage.
Cast iron is strong mechanically.
PVC and ABS resist acids and bases. ABS is much more resistant than PVC for solvents. Concrete is economical and is easily deteriorated. For any substantial reaction to occur, thorough mixing of components must take place. In sewage treatment, the microorganisms must be dispersed evenly through out the raw wastewater in order for BOD removal to occur.