Utilize carbon adsorption to remove chlorine, sediment, VOCs and SOCs from water.
Activated carbon (AC) filtration has been used for many years to solve water problems. Activated carbon quickly and effectively removes chlorine and many other contaminants from water. Carbon filters are most effective at removing chlorine, sediment, SOCs and volatile organic compounds (VOCs) from water. They are not effective at removing minerals, salts, and dissolved inorganic compounds. Carbon filters are usually apart of a more robust water filtration system. Untreated chlorine can cause irreversible oxidation to RO system membranes.
How carbon water filters work.
The 30-inch (770 mm) deep bed of a standard activated carbon media filter can operate at 10 gpm/ft2 (25 m/hr) or more. Synthetic organic chemicals (SOC) include all man-made organics, some of which are volatile organic compounds (VOC). Activated carbon can substantially reduce many VOCs such as benzene, trichlorethane and carbon tetrachloride. Activated carbon also removes SOCs such as Alachlor, EDB and toluene. The EPA is establishing limits for these chemicals in public drinking water supplies.
Before recommending treatment, water suspected of containing any of these and other substances must be analyzed to determine their concentrations and whether they exceed EPA standards. Equipment capable of providing empty bed contact tiem (EBCT) of 10 to 15 minutes is usually required to achieve sufficient contaminant reduction. That can require a large carbon volume, possible in two or more filters installed in series.
Activated carbon beds compact with use so they many need occasional backwashing. In general, however, backwash carbon when the pressure difference between the filter inlet and outlet increases by 5 – 10 psi (34 to 68 kPa) from the beginning of the filtration cycle. When operation a carbon filter on turbid water supplies, remove suspended particles with a depth filter before treating it with activated carbon. A carbon filter typically backwashes at 10 gpm/ft2 (25 m/hr) for about 10 minutes, followed by a 5 minutes downflow rinse.
Over a period of several months to two years, the carbon’s adsorption capacity diminishes. The exhausted carbon bed should be replaced with fresh carbon. The old carbon should be hauled to an approved disposal facility.