Sulphate removal in acidogenic phase anaerobic digestion

Abstract

The acidogenic phase of a two stage anaerobic digestion process using distillery molasses slops effluent with high sulfate concentrations (4.2–5.1 gl‐1) was investigated. Sulfate removal was studied at pH 5.4, 5.8, 6.2, 6.6 and in a stirred reactor (CSTR) and in an upflow fixed film fixed bed reactor operated at 22 h, 1.2 days retention time. The biological sulfate removal increased with pH and so did the acetic acid production from the fermentative and sulfate reducing bacteria. For the same pH and hydraulic retention time more efficient sulfate removal was obtained in the fixed film reactor than in the CSTR.