This is a conventional process to treat the hospital wastewater. In this process the wastewater is treated in open tank called aeration tank and air is supplied either through fixed / floating surface aerator or air blower to provide oxygen for the aerobic microbes. Around 12-15 hour hydraulic retention time is provided for the treatment of wastewater. The microorganisms utilize the oxygen in the air and convert the organic matter into stabilized, low-energy compounds such as NO3, SO4, and CO3 and synthesize new bacterial cells. The overflow carried to the adjacent clarification system contains active microbes and is required to be recycled back to aeration tank to maintain specified critical performance rating parameter like MLSS and F/M ratio.