Since the development of the UASB process in the 1970s this process has been widely applied for the treatment of industrial effluents. Effluents from alcohol producing industries are mostly highly polluted and therefore in principle very suitable for anaerobic treatment. Distilleries use different kinds of raw materials such as sugar cane juice, sugar cane molasses, sugar beet molasses, wine or corn for the production of alcohol. The use of different materials and the different processes applied, result in a wide variety of effluents produced. The process conditions under which good results of the anaerobic process are obtained depend heavily on the type of distillery effluent being treated. The choice of the right set of process parameters for every type of distillery effluent has shown to be of crucial importance for the anaerobic process. Experience of anaerobic treatment on effluents from different alcohol-producing industries over a long term period are discussed. Special attention is given to the treatment of effluents from sugar cane based distilleries with very high COD concentration of 60 000 to 160 000 mg COD 1−1. Despite expected toxicity problems arising from the high concentrations of COD, sulfide and salts, anaerobic treatment with the UASB process proved to be successful in treating distillery effluent.

To test the feasibility of anaerobic treatment of an effluent from a chemical factory producing intermediates for synthetic fibres, test work with a 45 l UASB pilot plant was conducted. Following its successful operation, a full-scale anaerobic effluent treatment plant including a 400 m3 combined pre-acidification tank and a 990 m3 Biopaq®-UASB reactor was constructed. The results of the pilot plant and the full-scale anaerobic treatment plant have been compared, similarities and differences in performance are presented and evaluated. COD removal efficiencies above 80% and BOD efficiencies in excess of 85% achieved in the pilot trial were confirmed by the full-scale installation. Overall process design as well as operational data from the pilot trial and the full-scale plant is presented. Despite the differences in configuration, operational results of the full-scale plant are comparable to the results obtained from the pilot plant study making such a pilot plant a useful tool for the process design of an full-scale anaerobic effluent treatment plant.

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Results of a 19 m3 demonstration plant studies are summarized. The plant is located at Sturgeon Falls at a NSSC mill and hardboard plant owned by MacMillan Bloedel. The mill discharges 6300 m3/day of waste effluent containing 50 tonnes of BOD and 127 tonnes of COD. Lab scale testing (1983) and an 18 month 1.4 m3 reactor volume pilot plant study (1985) were completed confirming treatability of the wastewater and suitability of the Upflow Anaerobic Sludge Blanket (UASB) technology among others to successfully treat the mill wastewater. Discharged effluent contains spent sulphite liquor and primary clarifier effluent. As required, the 1.4 m3 Biopaq System successfully achieved BOD reductions in excess of 75 percent at loadings greater than 10 kg COD/m3.d. As a consequence of this and because of economic considerations, the Biopaq System of Paques-Lavalin was selected for on site demonstration during a 12 months period. This period started in spring 1986. Erection of a full-scale plant is planned to take place in 1988. The purpose of the on site demonstration study is to confirm wastewater treatability, optimize design loading rates and confirm granular sludge growth. To achieve the objectives and simulate full-scale operating conditions the MacMillan Bloedel pilot plant has been automated and is controlled via a microprocessor incorporating a customized software program. Start-up performance results and operation at incremental loadings under steady state conditions are presented together with the experience gained during extreme variations in mill effluent quality and flow. Preliminary study results from the first 10 months disclose that a BOD removal efficiency of 80 percent or better is achieved at weekly average loadings of 15 kg COD/m3.d, and the process offers strong resilience to daily swings in wastewater quality. The results also show a net accumulation of granular sludge. The practical application of this technology from a mill operating perspective is discussed, and the layout for a full-scale installation with projected capital and operating costs is provided. Most of the contents of this paper was presented at the Tappi 1987 Environmental Conference (Prong etal, 1987). This paper presents the latest results.