Comparative Study on Hydrogen Production Characteristics of Pre-treated Swine Wastewater in ASBR Process
Swine wastewater, a high-strength organic effluent, offers a viable substrate for anaerobic biohydrogen production, aligning with clean energy recovery. This study compared hydrogen production in three anaerobic sequencing batch reactors (ASBRs) treating: raw wastewater (R1), supernatant after MAP (magnesium ammonium phosphate) precipitation for nitrogen and phosphorus recovery (R2), and the same supernatant with anaerobic sludge heat-treated at 75°C for 0.5 h (R3). Without pH adjustment, hydrogen production in R1 remained below 0.50 mmol/(kg·d). At an influent COD of 1800 mg/L, R2 and R3 achieved hydrogen production rates of 48.17 and 71.44 mmol/(kg·d), respectively. At COD 2400 mg/L, methane concentrations in R1, R2, and R3 were 10.8%, 14.2%, and 9.1%, respectively, indicating MAP pretreatment enhanced both hydrogen and methane production. As COD increased, R1's methane concentration rose to 14.6%, while average COD removal efficiencies for R1, R2, and R3 were 78.9%, 70.8%, and 52.5%, respectively. Under pH adjustment, all reactors peaked at pH 4.0, with hydrogen production rates of 0.10, 7.74, and 8.83 mol/(kg·d) for R1, R2, and R3, respectively. These findings demonstrate that MAP pretreatment combined with sludge heat treatment significantly enhances biohydrogen production, offering a promising strategy for swine wastewater valorization.