An activated sludge process refers to a multi-chamber reactor wastewater treatment unit to produce a high-quality effluent. Flocs of microorganism are suspended and mixed with wastewater in an aerated tank. As microorganism grow, they degrade organics and remove nutrients from the sludge and transform it to water, gas, energy and new cell material. To maintain aerobic conditions and to keep the activated sludge suspended, a continuous and well-timed supply of oxygen is required. An activated sludge unit is normally combined to a primary and tertiary treatment unit.