capacity and high efficiency dissolved air flotation

Introduction
DAF:An Advanced Wastewater Treatment
dissolved air flotation system is an advanced wastewater treatment used mostly in the industrial sector in the country to treat wastewater algae,organics,oil and grease.It is very efficient for the reduction of Chemical Oxygen Demand(COD)present in fat,grease,oil,biological Sludge,coloured organic matter, and colloidal material.
It is also excellent for removing oil and grease from industrial wastewater,as mentioned.
DAF has been used for treating drinking water clarification and treatment and is a common method of choice in drinking water treatment systems.
though,it is typically used in a wide range of industrial applications to comply and maintain environmental compliance.
Dissolved Air Flotation:Theory
What the DAF process does is to separate suspended contaminant particles from liquids,like oil and grease,by bringing them to the surface of the liquid.These light particles are thus easily removed using physical methods.
DAF also facilitates efficient wastewater and process water treatment through flotation with microbubbles.
The incoming wastewater into a DAF system usually requires pre-treatment.Chemical coagulant(s)and/or flocculant(s)are usually added and the adjustment of pH may may also be necessary to ensure optimum operating conditions for DAF.
Types of DAF
There are three types of DAF.
These are vacuum flotation,microflotation,and pressure flotation.
All work on a similar system,with minor variations.
Of these pressure flotation is the most important and widely used in water and wastewater treatments today.
Pressure Flotation
Flotation is an extremely critical part of wastewater treatment.
In pressure flotation what happens is that air is dissolved in water under high pressure and released at atmospheric pressure through a nozzle or needle valve to produce small air bubbles.
These air bubbles then make the lighter contaminants and suspended matter in the wastewater float on to the surface of the water in the flotation tank, and these can easily be removed by a skimming device.
This is the reason,Dissolved Air Flotation is widely used in treating the industrial wastewater effluents from pterochemicals,oil refineries,and chemical plants where the effluent is made of lighter solids.
General water treatments also use DAF for removing colour and organic particles like algae.
Induced gas flotation,a process similar to pressure flotation,is also used for wastewater treatment fairly widely.Froth flotation is also commonly used in the processing of mineral ores.
DAF- Process Description
Flotation Tank- For introducing Bubbles
The flotation tank is divided into two zones:the front zone,where the contact of the dissolved contaminants happen with the flocculants that are introduced to trap them.It is also called the reaction zone.
The other zone is the separation zone.A‘baffle’is fixed between the two to control flow.
Small air bubbles are introduced into the contactor reaction zone.This part of the flotation tank is actually designed to form bubble–floc agglomerates.
The bubble size is absolutely critical to form agglomerates.
In DAF,small bubbles are required to achieve an actionable solid–liquid separation.Infact,a bubble size in the range of 50–100μm is the most suitable for the DAF process.
If the bubbles are larger,they may create turbulence in the flotation tank and,simultaneously,decrease the surface area of the particle-bubble attachment.
To obtain the preferred bubble size,air is dissolved in a saturator under pressure delicately.
The pressure controls the total amount of air introduced into the contact zone at any given time.
Once the bubbles and contaminant particles come into contact through trapping,adhesion,or absorption process in the contact zone,the bubble–floc aggregates move on to the separation zone so that the process water can be clarified.
Separation Zone

This zone is designed to facilitate the rising of the bubble–floc aggregates to the surface of the flotation tank and float as a thick layer of sludge so it can be withdrawn.
The clarified and treated water/wastewater is withdrawn from the bottom of the separation tank.
This process makes the bubble-floc aggregates that do not reach the surface are swept out with the clarified water and these are then re-directed to another flotation tank for separation.

DAF Process
(A)The effluent enters the flotation tank clarification chamber
(B)Tiny air bubbles are released from diffuser nozzles into this chamber pre effluent entry
(C)These micro-bubbles attach to the solid contaminants or chemical flocculants.This causes the impurities like oil and grease to float to the surface and these are then trapped and removed using a mechanical skimmer
(D1)The skimmer consists of a series of paddles or flights in the flotation tank.These skim just below the surface of the flotation tank removing the floated sludge containing contaminants into a separate trough for recovery.
The clarified water flows to the bottom of the flotation clarifying chamber and then to an effluent control weir for separation and collection
(D2)The sinking solids are collected in the hopper and these are then removed via a manual or automated valve
(E)The final treated and clarified effluent gets discharged into a sewage drain or for further treatment,as required
Advantages of DAF Application in Treating Wastewater

Sewage Treatment Equipment

Rotary drumfilter

Dissolved air flotation machine sewage

High-efficiency Horizontal Dissolved Air Flotation

Horizontal Dissolved Air Flotation Machine Sewage

Flow Fine Grille

Sewage treatment equipment

Rotary drumfilter

Dissolved air flotation machine sewage

High-efficiency Horizontal Dissolved Air Flotation

Horizontal Dissolved Air Flotation Machine Sewage

Flow Fine Grille