Development of Thermophilic Treatment of Wastewater by Anaerobic UASB Reactor

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A laboratory-scale UASB reactor was operated 236 day by feeding with an alcohol distilllery waste, in order to investigate the granulation mechanism and microbial structure of retained sludge consortium under thermophilic conditions (55ﾟC). The reactor was inoculated with mesophilically-grows granulated sludge harvested from an UASB reactor receiving a carbohydrate (mainly juice) waste water.As a result of establishment of well-settleable, high-activity granuled sludge, the reactor allowed ultimately a volumetric organic loading of 30kgCOD/m^3/day, corresponding to HRT of 4.8 hours for influent strength of 9000mgCOD/l, with a COD removal efficiency of around 85%. The maximum sludge loading achieved was 0.92gCOD/gVSS/day.Methanogenic activities of the retained sludge increased finally up to 4.4 times for acetate, 4.6 times for propionate, and 3.5 times for hydrogen as large as those of the seed sludge (mesophilically granular sludge). Low values of the propionate-fed methanogenic activity compared to other trophic groups, indicate that the propionate breakdown is mostly subject to be a rate-limiting step in thermophilic methane fermentation process.