Many small communities across the U.S. and around the globe are struggling to meet more stringent nitrification of ammonia requirements on a tighter budget. When a South African community could not meet its state requirements and struggled with a failing rotor disc system, the town’s officials found an energy saving, affordable solution that met their unique needs and met all their new permit regulations.
The town of Op Die Berg is located in the Witzenberg Municipality, nestled in the Koue Bokkeveld mountain range that lies southeast of Citrusdal in the Western Cape Province of South Africa. The region is mountainous, with beautiful isolated peaks that average 6,000 ft high, but also has broad, fertile valleys that are home to some of the country's finest vineyards.
The town’s wastewater treatment facility consists of hand-rake screen pretreatment followed by an oxidation ditch for aeration and denitrification. The wastewater is then pumped up to a dortman tank which operates as a clarifier. Sludge is sent to drying beds and effluent to a nearby river.
The seasonal influent wastewater flow varies throughout the year from an average of 0.053 million gal per day (mgd) to a maximum of 0.132 mgd. A 20-hp disc aerator was used in the oxidation ditch but was not providing sufficient aeration. A second 20-hp disc aerator was out of operation. Bearings had failed once again and the gearbox needed replacement.
“The plant was not meeting the state’s requirements of ammonia removal through nitrification,” said Nathan Jacobs, town engineer for the Witzenberg Municipality. “Also, no denitrification was taking place for the removal of nitrate.”