As a result of increasing industrial activity and stricter application of environmental standards, pressure is being brought on Industries to improve the quality of their effluents. To achieve these goals, cost-efficient and high-performance wastewater treatment processes are needed. Recently, tests were completed on the treatment of ground wood, TMP and de-inking process effluents at the Daishowa, Quebec, pulp and paper mill. The biological treatment used was a fixed-film process known as the “Biocarbone” process. These tests demonstrated conclusively the high effectiveness of the Biocarbone process at COD loads of up to 10 kg/m3.day. This represents a major savings of space when compared to conventional waste activated sludge processes with COD loads of 2-3 kg/m3.day. The object of the test was to verify BOD5 levels, TSS removal and toxicity levels with respect to existing environmental standards. At all times and for all conditions tested, the Biocarbone process met the accepted standards of 5 kg/t of BOD5, 8 kg/t of TSS, and total removal of toxicity on a monthly basis