Evaluating the Full-Scale Impacts of Densified Activated Sludge on Disinfection Efficacy

Water resource recovery facilities (WRRFs) around the world are continuously faced with more stringent nutrient limits, population growth, limited footprint for process upgrades and increasing financial pressures. Two decades ago, biomass densifications and granulation approaches emerged as a serious alternative for WRRFs in need of fast, cost-effective and compact solutions to settleability challenges. Despite the many studies exploring advantages in densified activated sludge systems (DAS) compared to conventional activated sludge systems (CAS), many questions remain with regards to DAS impacts on microbial communities generally and fecal indicator bacteria (FIB) specifically. The main objective of this research is to provide a more conclusive and detailed understanding of the differences in FIB (E. coli) removal and disinfection kinetics in CAS and DAS trains in three full-scale, municipal WRRFs in North America.