The Hitachi Aqua-Tech conventional sewage treatment system is a biological / chemical plant for the treatment of domestic sewage. The following processes are involved:

• Anaerobic sludge digestion to reduce and stabilise concentrated organic solids
• Attached culture anaerobic and aerobic treatment to remove the organic and biological nutrients from the wastewater
• Settling, where treated water flows from the aeration tank into the sedimentation tank. Here, the activated sludge is allowed to settle down and recycled
• Chlorination to disinfect and reduce the number of microorganisms in the treated water before discharge

Membrane Bio-reactor (MBR) is a process that combines a membrane ultra / micro filtration process and activated sludge process.

The MBR process is used in place of the secondary sedimentation tank and sand filter used for tertiary treatment in the conventional activated sludge process.