Effect of polymer ferric sulfate on EPS in A2/O system

An A
²
/O system was built up to simulate Luchun wastewater treatment plant in Wuxi. Polymer ferric sulfate (PFS) was added into the system at the end of aeration tank to enhance phosphorus removal. When the dosage of PFS was 2.99 mg Fe/L, the average total phosphorus (TP) in the effluent was 0.24 mg/L, which met the discharge standard for municipal wastewater treatment plant, class A (GB18918-2002). Activated sludge extracellular polymer substances(EPS) in the A
²
/O system were analyzed in the experiment. The results showed that, the gross of EPS varied little after PFS addition. But the ratio of albumen and polysaccharide was declining. When the dosage of PFS increased, the concentration of total phosphorus of EPS in the aeration tank increased, while it increased slightly during the whole anaerobic-anoxic-aerobic cycle. The concentration of Fe
³⁺
in the EPS increased, as well as the concentration of TP in EPS in the secondary settling tank.