Activated sludge required for the biological treatments to be either brought from a Sewage Treatment plant or from industries employing activated sludge process for the treatment of their wastewater , Alternatively , an active biomass can be generated from cow dung or raw sewage.

If cow dung is used as the primary source for build-up grass and paper which are normally found in the cow dung has to be removed by providing necessary screening facilities. After transferring into the aeration tank it has to be aerated for about 72 hours before introducing the wastewater. To start with about 2000 mg/l of suspended solids shall be available in the aeration tank.

When fresh cow dung is added , around 12 tons per day of cow dung will he requires to build up biomass in each aeration tank until MLSS reaches to desire level.

Micro nutrient shall be provided by addition of 50 kg/day Urea and 50 kg/day DAP to the each aeration tank during biomass development however this quantity may be changed as per level of ammoniacal nitrogen and phosphate in the aeration tank.

Jeggary shall be added at 20 kg/day to the aeration tank. Jeggary shall be required during biomass development stage.

The biomass generated has to be acclimatized to the wastewater to avoid the exposure of the microorganisms present in the sludge to the concentrated wastewater . Generally , a limited quantity of the wastewater is introduced into the aeration tank in batches of short duration. The quantity is gradually increased by increasing the duration of batches till 100% wastewater feed is achieved within a period or three to four weeks. The suspended solids concentration in the aeration tank indicated as mixed Liquor Suspended Solids (MLSS) is analyzed everyday to monitor the growth of biomass.

About 10 kg/day of DAP and 10 kg/day of Urea is added in the each Aeration tank during acclimatization. However this addition quantity shall be changed as per ammonical nitrogen and phosphate concentrations of mixed liquor.