The Process

Once the MANTAIR packaged plant is installed, sewage entering the plant will discharge into the Aeration/Mixing Zone. Air is supplied to this zone via an aerator contained within a draught tube. Large and heavy solids are deposited in the Primary Settlement Zone. The aeration and mixing encourages the growth of aerobic micro-organisms which degrade the sewage.

The contents of this zone, where the micro-organisms are maintained in suspension, is referred to as the 'mixed liquor'. As further flows enter the tank, part of the mixed liquor is displaced into the Final Settlement Zone. Here the micro-organisms separate and form a thin sludge. This is continuously returned to the aeration/mixing zone, thus maintaining the levels of micro-organisms in the mixed liquor.

The liquid which remains in the upper part of final settlement zone is the treated effluent which is discharged from the plant via the Final Effluent Airlift.

The final effluent airlift controls the rate of discharge from the plant and prevents any shock hydraulic loads from upsetting the treatment process. The use of an airlift enables the MANTAIR packaged plant to discharge the effluent at a higher level than the tank inlet.

Specification

MANTAIR packaged plants are designed to treat domestic sewage and to achieve a final effluent standard of 20mg/lt B.O.D. and 30mg/lt Suspended Solids.

The MANTAIR system is designed in accordance with BS 6297:1983.