Comparative Study on Hydrogen Production Characteristics of Pre-treated Swine Wastewater in ASBR Process

• • MAP precipitation pretreatment elevated hydrogen production from <0.50 mmol/(kg·d) in raw wastewater to 48.17 mmol/(kg·d) at COD 1800 mg/L, a >96-fold increase, enabling energy recovery from high-strength organic waste. • • Co-treatment of MAP supernatant with sludge heat-treated at 75°C for 0.5 h further boosted hydrogen production to 71.44 mmol/(kg·d), a 48% improvement over MAP alone, demonstrating effective enrichment of hydrogen-producing bacteria. • • At pH 4.0, maximum hydrogen production rates reached 0.10, 7.74, and 8.83 mol/(kg·d) for raw, MAP-pretreated, and co-treated reactors, respectively, underscoring pH as a critical operational parameter for process optimization. • • MAP pretreatment increased methane concentration to 14.2% at COD 2400 mg/L versus 10.8% in raw wastewater, indicating enhanced overall anaerobic digestion efficiency, though COD removal was inversely affected (78.9% > 70.8% > 52.5%), likely due to accumulation of volatile fatty acids.