Control of the growth of Microthrix parvicella by using an aerobic selector – results of pilot and full scale plant operation

A two-stage wastewater treatment plant experiences in bulking sludge problems in winter, correlating with Microthix parvicella abundance. Pilot and full-scale studies of the use of an aerobic selector to control M. parvicella had little success, probably resulting from long chain fatty acid retention in foam at the tank surface. Initial pilot studies with reduced foam retention showed better results.