Polymer demand varies considerably for different digestion processes as well as the same digestion processes at different locations and the reasons for these differences are not known. The objectives of this research were to develop a mechanistic understanding for these differences. The differences were hypothesized to depend on both the amount of charge in a sludge sample and the characteristics of the polymer. The first phase of the research was aimed at establishing the component of the sludge that creates the polymer demand and the second phase was aimed at understanding the interactions...

The sudden increase in indicator bacteria, including fecal coliforms (FCs) and E. coli, was evaluated at several full-scale facilities, in addition to the increase measured during cake storage. The results showed that the sudden increase was a statistically verifiable occurrence at some facilities, but not all, as was the additional increases measured during cake storage. The sudden increase and growth were much more prevalent in processes that utilized centrifuge dewatering compared to belt filter press dewatering. The sudden increase appears to be a result of the reactivation of...