Use of Surface aerators in the reduction of BOD is an age old technique. Different designs of surface aerators have been used to improve the aeration of effluent and thereby reduction of BOD and COD.

The types used can be broadly classified as Fixed Type Surface Aerators and Floating Surface Aerators. Fixed type aerators are fixed to RCC structures and connected with operational platforms. Floating type aerators are mounted on platoons that keep the aerators floating. The location of the aerator can be changed by a link arrangement.

The surface aerators churn the effluent and bring it in contact with atmospheric air as the aeration process. This process poses the limitation of installation of large ponds and large numbers of surface aerators to improve the aeration efficiency. The disadvantage being a high capital cost in building basins, a high operating cost in terms of power consumption and high maintenance cost in terms of periodic cleaning of settled sludge at the bottom of the basin.

Paramount Limited make surface aerator is fixed slow speed type.

The oxygen transfer capacity of the unit shall range from 2.0 kg/kW/hr to 2.1 kg/kW/hr and the minimum ripple velocity at the farthest point would be 0.3 m/sec. The dissipation power will cause the whole mass to remain in the homogeneous condition.

Paramount make surface aerator comprises of:-

Impeller: The aerator impeller is provided with radial self cleaning blades, designed to give optimum oxygen transfer into liquid. The turbulence created by the impeller is sufficient to keep the sludge in suspension at the farthest point. The impeller is normally of mild steel construction (stainless steel impellers are also made) with a tubular shaft designed for required torsional capacity .The wetted parts are suitable for withstanding the corrosive condition of the effluent. The impeller has a self cleaning built in feature, which requires absolutely no maintenance of the impeller since no rags and other solids can get caught within the impeller vanes. The impeller is balanced statically.

Tubular shaft: It is of mild steel pipe (heavy duty) having concentrically machined flanges to connect gear box and motor assembly through rigid heavy duty coupling.

Drive unit: The aerator is driven by a motor of suitable rating. The speed is reduced from the motor speed to the aerator speed by a suitable reduction gear box having worm/helical gears. The speed of the aerator and the diameter of the impeller are so selected that aerator will have the optimum oxygen transfer capacity. The motor is of reputed make suitable for outdoor duties. The reducer bearings and gears are oil lubricated and weather protected.

Our range of manufacturing covers 3.0 HP, 5 HP, 10 HP, 12.5 HP, 15 HP, 20 HP, 25 HP, 30 HP, 40 HP, 50 HP, 60 HP, 75 HP and 100 HP fixed type surface aerators.

Adjusting studs: The depth of submergence can be adjusted by the adjusting studs. It is necessary to maintain the water level to avoid overloading of aerator drive.

Cascade Aerators

Aeration brings water and air in close contact by exposing drops or thin sheets of water to the air or by introducing small bubbles of air (the smaller the bubble, the better) and letting them rise through the water. The scrubbing process caused by the turbulence of aeration physically removes dissolved gases from solution and allows them to escape into the surrounding air.

A cascade aerator (one of the oldest and most common aerators) consists of a series of steps that the water flows over (similar to a flowing stream). In all cascade aerators, aeration is accomplished in the splash zones. Cascade aerators can be used to oxidize iron and to partially reduce dissolved gases.