Anaerobic biodegradability and toxicity of wastewaters from chlorine and total chlorine-free bleaching of eucalyptus kraft pulps

摘要: Abstract Chlorine bleaching effluents are problematic for anaerobic wastewater treatment due to their high methanogenic toxicity and low biodegradability. Presently, alternative processes being introduced, such as elemental chlorine-free (ECF) total (TCF) bleaching. The biodegradability of ECF TCF from oxygen-delignified eucalyptus Kraft pulp were compared with those different chlorine sequences. sequences had similar toxicities, 50% inhibiting concentrations (50%IC) 0.65–1.48 g-COD/litre. Only the effluent was distinctly less toxic, a 50%IC 2.3 fact that not toxic than bleaching, well residual TCF, indicate other substances aside organohalogens contribute in effluents. Literature data is presented suggesting wood resin compounds released by alkaline extraction stages might be important inhibitory all processes. Oxygen-delignified found highly biodegradable. When tested at subtoxic concentrations, COD anaerobically degraded 67 75%, respectively. In both cases, methane production accounted most removed. Therefore, process also enhances small extent.