Low dissolved oxygen sludge bulking in sequencing batch reactors

Abstract

In this paper, the effect of aeration rate on sludge bulking in sequencing batch reactors is considered. Cycles of 8 h, including 6 h aeration period, were applied. Raw wastewater with chemical oxygen demand equal 350 ± 20 mg/l was prepared using dried confectionery milk and tap water. Standard oxygen transfer efficiency equation in test condition was defined as y = 1.24981ln(x) + 13.86231. In low aeration rates that dissolved oxygen concentration cannot arise up to 2 mg/l during aeration period, low dissolved oxygen bulking occurred. Microthrix Parvicella was dominant filamentous micro‐organism. Bulking disappeared rapidly in 3–5 days when aeration rate increased.