Pfaffenbach Water Conditioning

Hydrogen sulfide (rotten egg smell) is present in some water, and is very objectionable. The sulfide in drinking water exists either as hydrogen sulfide, or, bisulfate. The use of catalytic carbon is commonly used in treatment as it combines absorption of activated carbon with enhanced catalytic function. In home water treatment, promotion of oxidation of sulfide with dissolved oxygen is accomplished.

In water where dissolved oxygen is less than 4 parts per million, the level is increased by injecting air, ozone, or, peroxide. Catalytic carbon facilitates the breakdown to form the required dissolved oxygen. Catalytic carbon requires a minimum of "empty bed contact time" of 3 minutes to contain the mass transfer zone, but, a contact time of 5 minutes is preferred for more efficient operation.

Back washing of catalytic carbon is critical in removal of precipitated, or, filtered matter. Catalytic carbon is backwashed at 10 gallons per minute per square foot. This expands the mineral bed about 40 percent, dependent upon water temperature and carbon particle size. A gravel  support bed with gravel size of 1/16 by 1/8 inch provides adequate distribution throughout during back washing. In water with hugh sulfide, pre-treated water is recommended for backwash purposes.

Most often where there is hydrogen sulfide, there also is the presence of iron. The use of catalytic carbon is also effective in iron removal as it has an oxidation-reduction reaction converting ferric (red water) iron in dissolved oxygen, as red water iron is insoluble and will precipitate from solution, thereby, easily filtered out by the carbon. If using catalytic carbon for hydrogen sulfide, with presence of iron, the filter bed must be increased by an additional amount of filtering media, and backwashing times.