Anaerobic toxicity of resin acids in chemithermomechanical pulp wastewater.

Abstract

In this study anaerobic toxicity assays were used to quantify the relative toxicity of resin acids to the total toxicity in bleached chemithermomechanical wastewater. Fiber toxicity was also compared to raw bleached chemithermomechanical wastewater toxicity. Resin acids were found to be toxic to anaerobic bacteria but were not found to be responsible for all the toxicity in the wastewater. Toxicity associated with the fiber is soluble in methanol. The bulk of the fiber which is not methanol soluble exhibits no toxicity. Transfer of information obtained from batch modified anaerobic toxicity assays to continuous anaerobic treatment systems was also evaluated. Modified anaerobic toxicity assay data was compared to continuous toxicity assays using an upflow anaerobic sludge bed reactor. The continuous reactor was relatively unaffected by acute or chronic exposure to resin acids at concentrations that invoked inhibition in bath tests. Inferences from these tests indicated that batch modified anaerobic toxicity assay results may be unreliable when applied to continuous systems. (Abstract shortened by UMI.)