Sand Filter
Sand Filter
(OP)
Please give me some information of the function and principle of sand filter. It's very urgent for me. I will feel very appreciated if you can give me any suggestion and information!
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RE: Sand Filter
Sand filters are used to remove suspended solids and debris out of water. (primarily) It's a cheaper option to do so. The top fine silica bed does the filtration action, while the increasing sized media do the support work. You have to backwash it when the pressure drop across the filter bed exceeds the manufacturer specification. (generally kg/sq.cm)
Regards,
Truth: Even the hardest of the problems will have atleast one simple solution. Mine may not be one.
RE: Sand Filter
Consider the sand filter as just another porous media. You have some control over the average pore size and pore length and head loss by the sand gradation, particle uniformity coefficient and depth of sand.
Sand filters are cheap. The sand may be completely or partially confined via a fabric and or a vessel.
As Quark stated, sand filters are usually intermittantly backwashed (forcing a semi-batch type operation) and wasting some fluid as backwash.
As Quark stated, these filter's are commonly used to filter water. We civil engineers use them in swimming pools, septic tank drain fields, polishing WWTP effluent (for tertiary treatment, use dual media - sand & activated charcoal for lagoon effluent polishing just sand), sludge drying beds, stormwater treatment ponds effluent filtration , etc...
The filters are usually design based on Darcy's Law. Q = K * I * A. with Q = flow of filtrate, K = tranmissivity of the sand in units of length per time. I = vertical drop divided by the length of the flow (dimensionless) and A is the cross sectional flow area. K's are available from the manufacturer of the sand. K may be divided by the safety factor.
RE: Sand Filter
Have fun...
RE: Sand Filter
Is there a formula?
Dollarbill