Anaerobic Digestion and In situ Electrohydrolysis of Dairy Bio-sludge

A novel treatment method based on anaerobic digestion and in-situ electrohydrolysis of dairy bio-sludge was investigated in this article. The electrohydrolysis was carried out inside the anaerobic reactor using graphite anode and stainless steel cathode. The electrons released by the graphite anode combines with the proton released due to electrohydrolysis of fatty acids which resulted in the formation of hydrogen gas. The experiments were conducted using a DC power source under continuous and intermittent mode of input voltage ranging from 0.5 to 2.5 V for varying influent volatile solids concentration at a pH 5.3 +/- 0.2. The results favored intermittent mode of input voltage rather than continuous supply. For an influent total solid concentration of 7% (64,120 mg/L VS), intermittent input voltage of 2 V, and a hydraulic retention time of 15 days resulted in a volatile solids and soluble COD removal efficiency of 83 and 74%, while the cumulative gas generation was 1,051 L with a hydrogen content of 72%.