Treatment of kraft condensates in a feedback-controlled sequencing batch reactor

A feedback-controlled sequencing batch reactor was used to treat kraft accumulator and evaporator condensates. The control strategy used the level of dissolved oxygen to terminate the oxidation phase and commence the settling phase of each cycle. The duration of the oxidation phase was automatically adjusted to achieve 100% removal of methanol, the major carbon source in the condensates. While the treatment rate varied substantially in response to influent variability, the overall level of treatment remained constant, averaging 88+/-5% and 64+/-2% COD removal for the accumulator and evaporator condensates, respectively. Generally over 90% of the reduced sulfur compounds were removed, apparently almost completely by stripping. Metal ion addition was found to be necessary to support biological growth in accumulator condensate. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.