The organic-loading rate and the nitrogen-loading rate were 0.065–0.075kg BOD 5/kg MLSS?d and 0.019–0.031 kg TKN/kg MLSS?d,respectively. The settling ability of the sludge throughout the experimental periods was generally better, with the sludge volume index (SVI) between 97 and 129 and the settling velocity(SV) of 35–40%.