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The performance of a membrane bioreactor treating wastewater from a metal transformation industry was compared with the ultrafiltration system at the mill. Toxicity analysis using the microtox and algal tests on the untreated and treated effluents from both systems showed a 130 fold reduction in toxicity due to the ultrafiltration step and a further 10 fold reduction due to the biological step. This resulted in a biomass which must be disposed of as a hazardous waste. In comparison with the present situation, the overall quantity of hazardous waste was reduced by a factor of 3 due to the combination of the bioreactor and the ultrafilters.

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

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Deviations from design expectations appear to stem from views which assume that a unique response should result from a given set of operating conditions. The results of this study showed that two systems operating at equal organic loads or F/M ratios and at the same SRT do not necessarily give equal responses. This deviation was linked to the manner in which the HRT and influent COD are manipulated to obtain a constant or uniform load, and to subtle interactions between influent COD, HRT and SRT on the biomass and effluent responses. Increases of up to 200% in influent COD from one steady level to the next did not significantly influence the effluent VSS concentration while an effect on filtered COD was observed for increases as low as 20%. Effluent TKN and filtered COD correlated strongly with the operating MLVSS while phosphorus residual depended on the operating SRT and the organic load removed. These results point to the inadequacy of traditional models to predict effluent quality and point to the need to consider these effects when developing simulation techniques or computer assisted expert systems for the control of waste treatment plants.