Does Polymer Have an Effect on Bacterial Regrowth in Anaerobically Digested Biosolids?

Recently more attention is being given to the regrowth of bacteria in treated biosolids. It has been found that in many anaerobically treated biosolids, bacterial regrowth occurs between digestion and the point in which the biosolids are disposed of or used for land application. This experiment examines the possible effect of polymer usage on bacterial regrowth in anaerobically digested biosolids. In order to examine this possible effect, a control sample, a sample with newly-reconstituted polymer, and a sample with pre-constituted polymer (several days old) were compared for their effects on bacterial regrowth using an MPN test. Each sample was 300mL, and a weight ratio of 1mg: 185kg, assuming 2% solids, was used to add polymer to all of the samples, excluding the controls. These samples were then compared at 0, 1, and 2 days of incubation. As a whole, the MPN values increased with one and two days of incubation at room temperature. However it was also found that the control samples had a higher MPN than the samples treated with the old and new polymer after one and two days of incubation, which suggests that polymer does not have an effect on the increase of fecal coliforms in biosolids.