Abstract:
The purpose of this experimental study was to determine the optimum operating conditions for treating distillery waste in a thermophilic UASB system. The studied UASB reactor was made from stainless steel with 34.7 litre (working volume), 172 cm. in height and 15 cm. inside diameter, with a water jacket to maintain the reactor temperature at 55ºc. The studied waste was distillery slops containing of high contents of organic (113,280 mg.COD/1) and toxic substances K⁺= 10,000 mg./l. Na⁺= 5,000 mg./l. SO₄²⁻=5,525 mg./l.). From the experimental results, it was concluded that the optimum organic loadings were 5.2 and 7.1 kg.COD/m3d. for maximum COD removal and maximum biogas production, respectively. Under maximum organic loading of 10.1 kg.COD/m.3d., the UASB system yielded 0.225 m.3/kg.COD removed, 0.099 m.3/kg.COD applied or 1.003 m.3/m.3d. The biogas produced contained 39% carbon dioxide and 61% of methane and other gases. At this maximum COD loading, the studied system yielded a COD removal of 44%. By comparison with the full-scale UASB operated at 30ºC., which had a maximum COD loading of 3-4 kg.COD/m.3d., it could be concluded that the thermophilic UASB provided better treatment for distillery waste than the UASB system operated at ambient temperature.