A novel bioreactor system for the destruction of volatile organic compounds

The biological treatment of waste-waters containing 1,2-dichloroethane (DCE) in conventional bioreactors results in air-stripping of DCE. In the present work, a novel bioreactor system intended to overcome this problem has been developed for the treatment of a synthetically concocted DCE-containing waste-water (1000 mg DCE l^–1). The operation of a conventional air-lift bioreactor at a waste-water flow rate of 0.24 l h^–1 led to 33% of the DCE supplied to the reactor being lost to the exit gas stream. The use of the novel enclosed system, operated with a recycling O₂ sparge instead of air, resulted in negligible air-stripping at the same waste-water flow rate. A control system was implemented to add O₂ as required to maintain the pressure of the recycle gas stream, and a scrubber removed the CO₂ produced. Over 99% of DCE supplied was biodegraded during operation of this system, and virtually all carbon entering the system was evolved as CO₂. Correspondence to: A. G. Livingston Correspondence to: A. G. Livingston