Primary Treatment

Primary Treatments

Clarifiers – HRSCC (High Rate Solid Contact Clarifier)
DAF (Disolved Air Floatation)
Lamella packs

(A) Clarifier

A clarifier is generally used to remove solid particulates or suspended solids from liquid for clarification and (or) thickening.Use of clarifier reduces the turbidity, removes colour, colloidal particles and solids from water before fed into downstream process. In conventional clarification process, there are 4 stages,such as Coagulation, Flash Mixing, Flocculation and Clarifications.

HRSCC (HIGH RATE SOLID CONTACT CLARIFIER)

Accelerated Clarifier is a high rate treating clarifier, which produces treated water of highest quality with minimum time, space and chemicals. In AC chemicals and large quantities of recalculating sludge’s are thoroughly mixed and are retained in close contact with each other for a prolonged period of time in the draft and cone sections of the solids clarifier. The intimate contact between the effluents, coagulant, polymer and previously formed sludge causes the chemical reactions to proceed at rapid rate with minimum use of chemicals. Furthermore, by contacting the water with the great volumes of sludge in circulation, maximum clarification of the water can be obtained by the adsorptive properties of the sludge or floccules which is formed.This type of clarifier increases settling efficiency due to the increased surface area. Also smaller area is required for installation of such types.

(B) DAF System

DAF is an excellent solution for clarifying water with high levels of low-density solids and algae that cannot be removed efficiently with sedimentation. Dissolved air flotation (DAF) is a proven and effective physical /chemical technology for treating a variety of industrial and municipal process and wastewater streams. DAF systems are commonly used for the removal of oils & greases and suspended solids to meet a variety of treatment goals including:

Pretreatment to meet sewer discharge limits
Pretreatment to reduce loading on downstream biological treatment systems
Polishing of biological treatment effluent
Thickening of biosolids
Product recovery and reuse

The DAF systems are designed to remove suspended solids (TSS), Biochemical Oxygen Demand (BOD), and oils and greases (O&G) from a wastewater stream. Contaminants are removed through the use of a dissolved air-in-water solution produced by injecting air under pressure into a recycle stream of clarified DAF effluent. This recycle stream is then combined and mixed with incoming wastewater in an internal contact chamber where the dissolved air comes out of solution in the form of micron-sized bubbles that attach to the contaminants. The bubbles and contaminants rise to the surface and form a floating bed of material that is removed by a surface skimmer into an internal hopper for further handling. Advantages of DAF System Uses small tanks high rise velocity permits usage of small tanks to handle variable solid loading. DAF can provide high float concentration & can remove low density particles which would require long settling periods.

(C) Lamella Clarifiers Systems

Lamella Clarifier system is to be used for surface water treatment along with pre-Coagulation and Flocculation system for removal of TSS, Colour, Algae etc.

This lamella Settler will provide large projected surface area in a limited space than conventional settler. The flocculated water sludge enters into lamella pack system and clear water move upwards and sludge will be settled down on packs and move downwards due to gravity, then removed from bottom of the tank intermittently

Lamella Clarifiers Advantages

The main advantage of lamella clarifiers over other clarifying systems is the large effective settling area caused by the use of inclined plates, which improves the operating conditions of the clarifiers in a number of ways.

Operation within an enclosed space also allows for a better control of operating temperature and pressure conditions.

Lamella clarifiers also offer a simple design without requiring the use of chemicals. They are therefore able to act as pre-treatment for delicate membrane processes, where necessary flocculants may be added to promote efficiency.