The Wastewater Treatment division of Tirta Wisesa treats industrial and commercial waste (such as domestic sewage waste) to the current regulation or better. These wastewater are usually treated for solids removal using conventional clarification and further treatment may involve biological oxygen demand (BOD) removal using biological methods or other hazardous contaminants by setting/absorption. More efficient systems using membrane bio reactors are becoming more and more commonly used because of the law sludge production and higher quality effluent. With new types of membranes. It is now possible to recycle some of the water for reuse. Similar to the water treatment systems, Tirta Wisesa also manufactures and assembles all these systems.