Rapid Sand Filter - Advantages and Disadvantages

Advantages and Disadvantages

Rapid sand filters are typically designed as part of multi-stage treatment systems used by large municipalities. These systems are complex and expensive to operate and maintain, and therefore less suitable for small communities and developing nations.

Advantages include:

• Much higher flow rate than a slow sand filter; about 150 to 200 million gallons of water per acre per day
• Requires relatively small land area
• Less sensitive to changes in raw water quality, e.g. turbidity
• Requires less quantity of sand

Disadvantages include:

• Large pore size will not without coagulant or flocculent remove pathogens like Crytosporidium smaller than 20 microns
• Requires greater maintenance than a slow sand filter. For this reason, it is not usually classed as an "appropriate technology," as the term is applied in less-developed countries.
• Generally ineffective against taste and odor problems.
• Produces large volumes of sludge for disposal.
• Requires ongoing investment in costly flocculation reagents.
• Treatment of raw water with chemicals is essential.
• Skilled supervision is essential.
• Cost of maintenance is higher.
• It cannot remove bacteria.