Process Intensification of Municipal Wastewater Treatment by Aerobic Granular Sludge Systems

Present wastewater treatment plants, like activated sludge systems, have the disadvantage of a large area requirement. Moreover these processes have to deal with a large number of conversion processes (COD-oxidation, ammonium oxidation, nitrate reduction, biological phosphate removal etc.) Traditionally, flocculated sludge with low settling velocities is applied, which leads to a low hydraulic load on the settling tanks. Therefore, large settling tanks are needed to separate clean effluent from the organisms. Besides large settling tanks, separate tanks are needed to accommodate the different treatment processes. Conventional processes need many steps for nitrogen, COD and phosphate removal, with large recycle flows and a high total hydraulic retention time. Surplus sludge from a municipal wastewater plant needs different steps to dewater (e.g. thickening and filterpressing) before it can be processed.