Centralized wastewater treatment plants are designed to treat sewage from small villages with 1000 population equivalent (PE). If the biological reactors are combined, the number can be increased up to about 200 000 PE. The units are intended for anything from factories to small towns. Biological wastewater is treated and purified to the required level which can then be reused or discharged into open water bodies or the soil.

Wastewater treatment plants consist of two or more parallel-connected treatment lines with the biological reactors and sludge tank in one compact unit and have additional building structures and machinery such as pump station, mechanical pretreatment, sludge management, tertiary treatment, instrumentation, and controller.

Serves 1 000 population equivalent. The number can be increased to 200 000 by combining multiple biological reactors.