South African Advances in Nutrient Removal

The prime emphasis in South African wastewater treatment works was on phosphorus removal with nitrogen removed mostly to prevent the detrimental effects of nitrate in enhanced biological phosphorus removal. Developments in nutrient removal process technology are described including: sidestream fermentation processes to generate volatile fatty acids, enhancing phosphorus removal; the Johannesburg modification of the Badenpho process (JHB); the University Cape Town (UCT) and modified UCT processes; chemical polishing to meet low phosphorus requirements by adding chemicals directly to the anaerobic zone; nitrogen removal in the aerobic zone; and treatment of solids sidestreams. Unlike the U.S.A., new treatment options frequently received full-scale testing at local operating facilities. Testing of the 3-stage UCT process (a sequence of anaerobic, anoxic, aeration and clarifier), the modified UCT process (a sequence of anaerobic, anoxic, anoxic, aeration and clarifier) and the JHB process (a 4-stage sequence of anoxic, anaerobic, anoxic and anaerobic treatments) to optimize phosphorus removal and reduce the need for supplemental chemicals are discussed.