Biohydrogen production from co-digestion of cow manure and waste milk under thermophilic temperature

Biohydrogen production from co-digestion of cow manure (M) and waste milk (WM), milk from mastitis cows treated with cefazolin, was evaluated in a 3 × 5 factorial design. Organic loading of 20, 40 and 60 g volatile solid (VS) L−1 were tested at temperature of 55 °C using M:WM (VS/VS) 70:30, 50:50, 30:70, 10:90 and 0:100. Hydrogen production increased with organic loading and M:WM to a maximum of 59.5 mL g−1 VS fed at 40 g VS L−1 in M:WM 70:30. Butyrate was the main volatile fatty acid (VFA) accumulated in M:WM 50:50, 30:70 and 10:90. Overall reduction of more than 90% of cefazolin resistant bacteria was observed in all the treatments. The reduction was higher at 40 and 60 than 20 g VS L−1 (P < 0.05). Inclusion of waste milk enhances hydrogen production from cow manure and could offer added benefit of waste milk treatment and disposal.