The recycle ratio considered while designing dissolved air floatation process is 6-12. This holds good for conventional type dissolved air floatation process. This is also true in case of high rate dissolved air floatation process.

The length of lamella clarifiers is 1-2 m with a plate or tube spacing of 50 mm. The minimum plate pitch is 7? and typical loading rate is 5-10 m/h.

Lamella clarifiers can be used in a range of industries including mining and metal finishing, as well as used to treat groundwater, industrial process water and backwash from sand filters.

The typical A/S ratios encountered in a Dissolved air floatation method is 0.005-0.06. Floatation depends on solid loading rate and particle rise velocity. It also depends on concentration of particulate matter and quantity of air used.

The bentonite has a charge of 70-90 meq/gram. After it is treated with quaternary amine, some 30-40 meq/gram remain, resulting in organo clay also removing small amounts of common heavy metals such as lead, copper, cadmium and nickel.

The hydraulic loading rate considered for a high rate of dissolved air floatation is 10-30 m/h. The mixing intensity is considered as 50-100 sec^-1. Usually, basin depth is considered 2.5-4.5 m.

Wastewater is treated by bacteria that live in septic tank. The longer water is held in tank, better treatment. Crowded households may produce large quantities of grey water from constant use of washing machine, shower and bath.

A maximum feed water concentration of 1000 mg/L of grease and 3000 mg/L of solids can be handled by lamella clarifiers. Treated water has a turbidity of around 1-2 NTU.

The scum formed in tanks floats over top. Over time, solids that settle to bottom are degraded anaerobically.

The oil load is calculated as Flow rate x oil present. It is expressed as Kg/h. The oil load is expressed as Flow rate x oil present = 90 x 50 / 1000= 4.5 Kg/h. The density of oil = 0.9 gm/cc. Therefore oil skimmer required is 4.5/0.9 = 5 LPH.