Anaerobic treatability and biogas production potential of selected in-mill streams.

Biochemical methane potential assays (BMP assays) were performed to study the potential of anaerobic treatment of in-mill wastewaters. The assay results indicated that condensate and the BCTMP effluent, which are currently treated with the anaerobic internal circulation reactors, were the best streams for anaerobic treatment because of their relatively high degradability (>80%) and initial rates of biogas production. The softwood dewatering process stream was the worst with the lowest degradability (~30%). The hardwood stream was more degradable than the softwood stream from the same process. Biogas production was found to be additive and predictable in blended samples. In addition, degradability was found to be negatively correlated to the concentration of dehydroabietic acid and tannin-lignin compounds. The anaerobic treatment of the suitable streams has great potential value with significantly reduced sludge production and energy savings.