Around 15-20% of Dissolved air floatation effluent is recycled. The recycled flow is mixed with unpressurized main stream prior to letting it inside floatation tank. This process is mainly used to treat industrial wastes.

The pressure is calculated by this formula A/S = 1.3 S_a (fP-1)/S_a. Then P= p+101.35/101.35. p= 302 kPa.

Surfactants and finely divided solids increase stability of emulsion. An emulsion is a heterogeneous system that consists of at least one immiscible liquid intimately dispersed in anor liquid in form of droplets, whose diameter generally exceeds 0.1 microns.

The separation zone loading rate for a conventional dissolved air floatation process considered is 6-18 m/h. In case of high rate dissolved air floatation process it is considered as 20-40 m/h. It is higher in case of high rate air floatation process.

One specific application is as pre-treatment stage for effluent entering membrane filters. Lamella clarifiers are considered to be one of best options for pre-treatment ahead of membrane filters.

The top bridge takes three minutes to rotate around rim. Millions of air bubbles in DAF tank float solid particles upwards forming a sludge blanket.

By using a soak pit, Evapo-transpiration mound or leach field, effluent of septic tank must be dispersed or transported to anor treatment technology via a solids-free sewer, simplified sewer or solids-free sewer.

The flow per plate is calculated as rise rate multiplied by per area of plate. Then total flow is divided by flow per plate. The answer obtained equals to number of plate required. In this case no: of plates = 120/ (0.9 m³/m²/h x 1.8 m²)=75

The mixture of methane and carbon-dioxide of an anaerobic digestion is called biogas. Over time, anaerobic bacteria and micro-organisms start to digest settled sludge anaerobically, transforming it into CO₂ and CH₄ and some heat.

The retention time for circular and lamella clarifiers is 1-2 hours and retention time for rectangular clarifiers and floc blanket is 2-3 hours.