Abstract: The pilot-scale experimental apparatus and the procedure of the
chemical and biological flocculation process to verify the feasibility in
treating Shanghai municipal sewage were introduced in this paper. In addition,
the biological function of the process was discussed. The results of optimal
running showed that in the reaction tank, the concentration of mixed liquor
suspended solid (MLSS) was 2 g/L, hydraulic retention time (HRT) was 35 min,
dosage of liquid polyaluminium chloride (PAC) was 60 mg/L, and the
concentration of polyacrylamide (PAM) was 0.5 mg/L. The effluent average
concentrations of COD_{cr}, TP, SS and
BOD_5 were 50 mg/L, 0.62 mg/L, 18 mg/L, and 17 mg/L,
respectively. These were better than the designed demand. In addition, the
existence of biological degradation in this system was proven by several
methods. The removal efficiencies of the chemical and biological flocculation
process were 20% higher than that of the chemical flocculation process above at
the same coagulant dosage. The treatment process under different situations was
evaluated on a pilot-scale experiment, and the results provided magnificent
parameters and optimal condition for future operation of the plant.
Keywords: chemical and biological flocculation process, municipal water, biological function
