Biological sludge reduction and enhanced nutrient removal in a pilot-scale system with 2-Step sludge alkaline fermentation and A2O process

doi:10.1016/j.biortech.2010.12.051- Bioresourse Technology (2010)
Yongqing Gao, Yongzhen Peng, Jingyu Zhang, Shuying Wang, Jianhua Guo and Liu Ye

Abstract

To enhance nutrient removal performance and reduce disposal amount of waste activated sludge (WAS), a pilot-scale continuous system consisting of a 2-step sludge alkaline fermentation process and an A²O reactor was proposed. The feasibility of WAS reducing and resourcing by alkaline fermentation was investigated. Volatile fatty acids (VFA) yield was higher under alkaline condition than that under acidic condition. Through 2-step alkaline fermentation, substantial VFA was accumulated, and then elutriated out continuously from an up-flow column by domestic wastewater. The results showed that 38.2% of sludge was hydrolyzed, 19.7% was finally acidified into VFA, and as high as 42.1% of WAS was reduced. Moreover, after introducing the fermentation liquids with higher proportion of acetic acid and propionic acid into the A²O reactor, the total nitrogen and phosphorus removal efficiencies reached to 80.1% and 90.0%, respectively. Sludge reduction and enhanced nutrient removal could be achieved simultaneously in the proposed system.

Key words: Waste activated sludge; Alkaline fermentation; Sludge reduction; Volatile fatty acids; Biological nutrient removal; Sludge resource