Pressure Sand Filters [ Multigrade Sand Filters]

These filters are the most popular method for removal of turbidity from water. The Pressure Sand Filter consists of a multiple layer of sand with a variety in size and specific gravity. These Filters are designed to remove turbidity and suspended particles present in the feed water with minimum pressure drop. These Filters are custom designed to suit the process requirement. These filters are offered in Mild Steel, FRP or SS construction with face piping and associated Valves.

Construction

The Pressure sand filter consists of a pressure vessel either vertical or horizontal, with a set of frontal pipe work and valves, graded silica quartz sand supported by layers of graded under bed consisting of pebbles and gravels, a top distributor to distribute the incoming water uniformly throughout the cross section of the filter, and an under drain system to uniformly collect the filtered water.

Process

Raw water flows down wards through the filter bed and as the suspended matter, which is treated by addition of a coagulant like alum or poly electrolyte, is retained on the sand surface and between the sand grains immediately below the surface. There is steady rise in the loss of head over a period of time and the flow reduces once the pressure drop across the filter is excessive.

The filter is then taken out of service and cleaning of the filter media is effected by flow reversal also called as backwash. To assist in cleaning the bed, the backwash operation is sometimes preceded by air scouring by way of agitation through the under drain system. The air scouring agitates the sand with a scrubbing action, which loosens the intercepted particles. The filter is now ready to be put back into service.

We Offer the following Range of Pressure Sand Filters:

• FRP Pressure Sand Filters up to 2000 mm Diameter
• Vertical MS Pressure Sand Filters up to 5000 mm Diameter
• Horizontal MS Pressure Sand Filters up to 4000 mm Diameter

Pressure Sand Filter - Salient Features:

• Efficient Turbidity Removal
• MOC - FRP, MSRL, MSEP & SS
• Standard and effective multi grade sand media.
• Low Pressure drop across the vessel
• Optional Air scouring available.
• Manual, Semi Automatic & Automatic Options

Covalence EnviroTech offers Chemical handling and Dosing Systems for dosing Coagulants like Lime. Ferrous Sulfate, PAC, Alum and Feed Conditioning chemicals like Anti-scalant, Antioxidant, Membrane cleaners etc. Dosing systems are Skid mounted, compact and rugged, engineered to handle and work efficiently under highly corrosive and varying conditions.

The areas of application include

• Raw Water Treatment
• Waste Water Treatment
• Reverse Osmosis
• Ultra Filtration
• Cooling Water Treatment
• Boiler Feed Treatment

Typical Dosing systems consist of Metering type pumps with varied material of construction to suit the chemical handling. All Dosing Systems can be upgraded to a high level of automation for link up to a localized PLC or client's DCS as required.
Pre-engineered designs conform to International safety norms with respective to spillage and containment.