The seed sludge was obtained from the aeration tank of a local sewage treatment plant.
The initial sludge concentration in the experimental oxidation ditch was 2.6 g/L, and it was operated at a sludge retention time of 20 days.
During this trial, the mixed liquor suspended solids (MLSS) in the experimental oxidation ditch remained at a concentration of 2.3-4.3 g/L, and the loading rates of COD, NH4 + -N, TN and TP were 96-179, 21-40,30-55 and 3-6 mg/(g MLSS.day),respectively.