Effect of Chemical Spills on Treatment System Microorganisms, 1997 Environmental Conference Proceedings

Microorganisms in biological treatment systems are susceptible to the effects of toxic substances released to mill sewers. This study evaluated the potential impact on an activated sludge system of chemicals used by a newsprint mill. Information from mill staff and chemical suppliers was used to identity twenty-three mill chemicals that may have the potential to impact the mill’s biological effluent treatment system. Dye tracers were used to evaluate the time of travel between potential spill points in the mill and the activated sludge treatment system. Travel times were found to be very short, averaging 10 minutes from the spill discharge point to the bypass point located before the primary clarifier, making diversion of spills prior to the clarifier very difficult. Bio-sludge was then exposed to each chemical at the estimated worst-case and realistic spill concentrations to assess the effect, if any, on sludge viability. Four chemicals were shown to moderately reduce sludge viability. The data suggested that, although treatment efficiency may be reduced, none of the chemicals were likely to completely kill the treatment system. Improvements to containment and handling practices for these chemicals were implemented.