The moving aerated media process used is a compact development of the traditional biological process and provides a more effective and complete means of reducing the loads.
1. Raw sewage gravitates to the unit where it is received in the primary settlement zone. Here, gross solids and other social debris settle to the bottom of the tank where they remain until the tank requires desludging. Settled sewage is displaced from primary zone and enters the first of two sequential moving aerated media reactors.
2. Media and liquid circulation in each zone is achieved through the use of a compressor and diffuser, which introduces fresh air into each compartment. The liquor is constantly re-circulated and contacts the moving media and as it does so, it is purified by the microorganisms (biomass) growing on the surface of the media and within the moving liquor. Excess growth of biomass is shed as solid particles into the liquor.
3. The final settlement tank is where humus solids settle to form sludge. At preset intervals, portions of the sludge and liquor are returned to the primary tank for additional treatment.
4. Final effluent is displaced from the final settlement tank. With regulator approval, it is suitable for discharge to a watercourse or drainage field.