Control of sludge settleability and nitrogen removal under low dissolved oxygen condition

• Published in: Frontiers of Environmental Science & Engineering 2012-12, Vol.6 (6), p.884-891
• Main Authors: Peng, Zhaoxu, Peng, Yongzhen, Yu, Zhenbo, Liu, Xuliang, Li, Xiaoling, Wang, Randeng
• Format: Article
• Language: English
• Subjects: Activated sludge; Activated sludge process; Aeration; Anaerobic conditions; Bacteria; Batch reactors; Bulking sludge; Cycle time; denitrification; Dissolved oxygen; Domestic wastewater; Earth and Environmental Science; energy; Energy consumption; Environment; Filamentous bacteria; limited filamentous bulking; Municipal wastewater; Nitrification; nitrogen; Nitrogen removal; Reactors; Research Article; Sequencing batch reactor; simultaneous nitrification denitrification; Sludge; sludge settleability; Sludge volume index; Wastewater; Wastewater treatment; 不稳定状态; 丝状菌污泥膨胀; 低溶解氧; 同步硝化反硝化; 序批式反应器; 控制; 曝气时间; 污泥沉降
• ISSN: 2095-2201; 2095-221X; 1673-7520
• DOI: 10.1007/s11783-012-0408-9

Low dissolved oxygen （DO） is an energy- saving condition in activated sludge process. To investi- gate the possible application of limited filamentous bulking （LFB） in sequencing batch reactor （SBR）, two lab-scale SBRs were used to treat synthetic domestic wastewater and real municipal wastewater, respectively. The results showed that prolonging low DO aeration duration and setting pre-anoxic （anaerobic） phase were effective strategies to induce and inhibit filamentous sludge bulking, respectively. According to the sludge settleability, LFB could be maintained steadily by adjusting operation patterns. Filamentous bacteria content and sludge volume index （SVI） were likely correlated. SVI fluctuated dramatically within a few cycles when around 200 mL-g~, where altering operation pattern could change sludge settleability in spite of the unstable status of activated sludge system. Energy consumption by aeration reduced under low DO LFB condition, whereas the nitrification performance deteriorated. However, short-cut nitrification and simultaneous nitrification denitrification （SND） were prone to take place under such conditions. When the cycle time kept constant, the anoxic （anaerobic） to aerobic time ratio was determining factor to the SND efficiency. Similarity keeping aerobic time as constant, the variation trends of SND efficiency and specific SND rate were uniform. SBR is a promising reactor to apply the LFB process in practice.