Improving hydrogen recovery from anaerobic co-digestion of algae and food waste by high-pressure homogenisation pre-treatment

Lake algae can be digested anaerobically to produce hydrogen (H2), but the efficiency of actual processes is limited. Improving the hydrogen yield could be done by hydrolysis and tuning nutrients. Here, we pre-treated Taihu lake algae by high-pressure homogenisation; then, this product was co-digested with food waste for hydrogen recovery. Results showed that the average particle size of algae decreased to 65.48 μm after 60 MPa pre-treatment, which is 43.09% smaller than that the control. The disintegration degree rose from 1.54% to 23.13%, and the soluble chemical oxygen demand rose from 3.21 g/L to 11.20 g/L in wet algae after 100 MPa pre-treatment. The maximum hydrogen yield was 39.87 mL per g of volatile solids. The pre-treatment effect on hydrogen generation performance was not significant when the pressure exceeded 60 MPa. Overall, we observed that high-pressure homogenisation is a fast and efficient method for algae pre-treatment, thus promoting anaerobic co-digestion of wet algae and food waste for hydrogen bio-recovery.