| Abstract | We conducted a laboratory scale feasibility study on the anaerobic treatment of spent pulping liquor effluent in upflow anaerobic sludge bed reactors. Tests showed that, in spite of high levels of sodiuk and lignin in the liquor, up to 80% of CODs can be successfully removed at a specific removal rate of 0.22 g and 0.57 g COD g⁻¹ VSS d⁻¹ for mesophilic and thermophilic conditions, respectively. Throughout the experiment, lignin accumulation occurred in the mesophilic, but not in the thermophilic reactor. Lignin measurements confirmed that up to 59% of lignin was degraded under thermophilic conditions. Higher activity of thermophilic biomass coupled with higher solubility, and therefore bioavailability of lignin under thermophilic conditions, contributed to the observed lignin removal. |
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