RETRACTED: Effects of Organic Loading Rate on the Formation and the Phosphorus Removal of Granular Sludge (Retracted Article)

In this study the influence of Organic Loading Rate (OLR) on the formation and phosphorus removal efficiency of granular sludge was investigated in an Sequencing Batch Reactor (SBR). The SBR was operated as an alternating anaerobic-aerobic cycle, and the Dissolved Oxygen (DO) concentration in the period of aerobic feast time in an SBR-cycle was maintained 1 similar to 2mg/L, the low DO concentration was obtained by reducing the air flow rate. Experiment results showed that, the sludge in the SBR was the mixture of a majority of activated sludge floc and a small quantity of round-shaped granular at the OLR of 0.482 similar to 0.986kgCOD/(m(3).d); granulation was accelerated at the early time of the OLR of 2.218 similar to 2.263kgCOD/(m(3).d), while the morphology of granules changed to an irregular shape on the end of the OLR of 2.218 similar to 2.263kgCOD/(m(3).d); then the OLR decreased to 1.113 similar to 1.182kgCOD/(m(3).d), the mature granules was cultivated successfully at this OLR, due to the combination effects of the low DO and the OLR. The OLR had also influence on efficiency of phosphorus removal, when the OLR was elevated to 2.218 similar to 2.263kgCOD/(m(3).d), competition between GAOs and PAOs was triggered. Which led to efficiency of phosphorus removal declined, and could not recovered even if the OLR was decreased to 1.113 similar to 1.182 kgCOD/(m(3).d). (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Organizers of 2011 International Conference on Energy and Environmental Science.