Biological filters are commonly employed for the oxidation of carbonaceous and nitrogenous material without the need for expensive power driven machinery. Most filters are circular because this shape accommodates simple rotating distributors that are designed to evenly distribute effluent over the filter surface by the reaction of discharge from the distribution arms. The Lektratek rotary distributor comprises of a stationary inner column and a rotating outer distribution tank to which two, four or six distribution arms are attached. The distribution tank is completely open thus preventing the accumulation of corrosive gases.

Country South Africa