Anaerobic Toxicity of Resin Acids in Chemithermomechanical Pulp Wastewater

Resin acids are present in a number of wood processing wastewaters. These wastewaters are being treated anaerobically although, at present, little is known about the effects that resin acids have on anaerobic bacteria or of their fate in an anaerobic environment. Andersson and Welander ¹ reported an abietic acid/oleic acid mixture to be inhibitory at 1,178 mg/L. However Köster and Cramer ² reported inhibition to 50% of control activity by oleic acid at 1,235 mg/L which left some doubt as to the effect of abietic acid. Field et al. ³ found 50% of control activity for an abietic acid concentration of 114 mg/L. McFarlane and Clark ⁴ reported that resin acids are degraded in an upflow anaerobic sludge blanket (UASB) reactor with the exception of dehydroabietic acid. It was also concluded by the same authors that anaerobic bacteria could acclimatize to high levels of dehydroabietic acid.