Wastewater treatment begins with an equalization tank to stabilize flowrate and wastewater
characteristics. If the wastewater temperature is high, a cooling tower may be used before equalization tank. Primary treatment units such as clarifier, CAF, or DAF are then used to remove suspended solids, oil and grease, and other separable impurities.
For high organic wastewater, UASB can be applied as an anaerobic treatment stage to reduce COD and BOD load. It is commonly followed by aerobic treatment, such as Acticontact Tank and Aeration Tank, to further polish the effluent. After aerobic treatment, a clarifier can be used for biomass separation in a conventional system; however, if MBR is applied, the membrane performs the solid-liquid separation, producing clearer effluent and making it a good pretreatment when the treated water will be recycled.
Sludge generated from the treatment process is collected and dewatered using equipment such as a screw press or filter press to reduce its volume and improve handling, transportation, and disposal.