Dechlorination and detoxification of bleach plant effluent by Phanerochaete chrysosporium

Dechlorination, detoxification, and decolorization of the first alkaline extraction stage (Ep) effluent from a pulp mill bleach plant were studied during fungal treatment. The original Ep effluent and Ep effluent fractionated by ultrafiltration were treated with the white-rot fungus Phanerochaete chrysosporium under agitated conditions. The fungus was grown from spores for 4 d. Decolorization was observed 2 d after the addition of fresh media containing reduced levels of nitrogen and carbon. After 2–3 d reaction time detoxification, dechlorination and decolorization were evaluated. Color removal was most effective in the MW > 10 000 (HMW) fraction. Toxicity as measured by the MICROTOX bioassay, increased in both the HMW and MW 1000–10000 (MMW) fraction after fungal treatment. Molecular weight decreased during fungal treatment, which may have caused the increase in toxicity. The amount of chlorinated organic compounds, as measured by adsorbable organic halide analysis (AOX), decreased in each fraction.