Bioaugmentation for polyacrylamide degradation in a sequencing batch reactor and contact oxidation reactor

In the present study, one PAM degrading bacterial strain, originally named HWBI, was isolated from an activated sludge sample and used as an exogenous bacteria for bioaugmentation. The strain was primarily identified as Bacillus cereus. One contact oxidation reactor (COR) and one sequencing batch reactor (SBR) were bioaugmented with the HWBI, respectively, and the performance of the bioaugmented systems for PAM removal were investigated under long term operation. Results showed that for the COR augmented with HWBI, 70% of PAM was removed at the end of the 7th day after a single inoculation, and the removal efficiency remained at approximately 70% in the following 45 days after a single inoculation. For the SBR augmented with HWBI, 70% of PAM was removed at the end of the first operation cycle, and the removal remained at approximately 70% in the following eight cycles after a single inoculation. The results indicate that HWBI is an efficient exogenous bacteria for bioaugmentation for PAM removal. Although the COR and SBR were both appropriate reactors that may be used for treatment of PAM using bioaugmentation, the COR was found to be a more time-efficient method compared to the SBR. A molecular screening technique, terminal restriction fragment length polymorphism (T-RFLP), was applied to track the supplemented bacterial strain and to evaluate the effects of bioaugmentation on the microbial communities and to investigate the optimal bioaugmentation strategy.