Effect of chemical and physical parameters on a pulp mill biotreatment bacterial community

The bacterial community composition in an activated sludge plant treatment from a bleached kraft pulp mill was monitored over a period of 209 days. Using DGGE and terminal-Restriction Fragment Length Polymorphism (t-RFLP) analysis we generated community DNA fingerprints over the time period. Both methods produce fingerprints that can be used to monitor stability in the system and generate fragments that can be associated with bacterial taxa. Chemical and physical parameters were also collected during that same time frame. We found a number of significant correlations with influent variables such as temperature, chemical oxygen demand (COD), Biochemical oxygen demand (BOD) and chloroform concentrations suggesting that these were the most likely parameters to influence the bacterial community structure. In addition several taxa correlated to important performance indicators such as COD/BOD removals and SVI. Multivariate analysis also confirmed the strong links between taxa variation and temperature, nutrient loads, chloroform and also one class of filaments. Establishing the identity of these taxa and their ecological preferences will greatly enhance our understanding and management of biological treatment systems.