The sulfate-reducing bacterium, Desulfovibrio desulfuricans, was grown in sulfate-enriched liquid manure from industrial pig farming. The contribution of the COD/SO4 ratio (which varied from 0.4 to 3.1) to the efficiency and rate of GOD removal was investigated. The highest efficiency of organic substances degradation (81.2 to 84.5%) was achieved with a COD/SO4 ratio ranging between 0.4 and 0.8. The reduction reaction ran at the fastest rate when the COD/SO4 ratio fell within 0.8 and 1.3.