Abstract:

Aluminum sulfate （AS） and polyacrylamide （PAM） were used as the flocculants to remove phosphorus from the influent of Unit B in an adsorption-biodegradation （AB） process in laboratory scale. Then, the influences of flocculant dosage on the removals of total phosphorus （TP）, chemical oxygen demand （COD）, ammonia nitrogen （NH4^＋ -N） and turbidity were analyzed, and the optimal dosage was determined. Finally, the relationship between the chemically-enhanced process and the biological process in terms of total phosphorus, COD, NH4^＋ -N and turbidity removals were evaluated. The results indicate that （ 1 ） the compound of AS and PAM is effective in removing the TP in the influent of Unit B; （2） with the addition of 9. 5 mg/L AS （calculated with Al₂O₃ ） and 0. 05 mg/L PAM, the average removal efficieneies （REs） of TP, COD, NH4^＋ -N and turbidity respectively reach 89. 2% , 37. 7%, 2. 41% and 71.6% ; （3） when adding AS and PAM, the REs of TP, COD and turbidity in the aeration process all increase except for the RE of NH4^＋ -N ; and （4） although the postpose flocculation process is more effective in removing TP, COD and turbidity than the simultaneous one, the latter is more suitable for the chemically-enhanced phosphorus removal with AB process because the former needs additional sedimentation equipment.

Key words: wastewater, flocculation, chemically-enhanced phosphorus removal, adsorption, biodegradation