Synergetic pretreatment of algal biomass through H₂O₂ induced microwave in acidic condition for biohydrogen production

The objective of the present study is to improve the biohydrogen production from marine macroalgae (Ulva reticulate)by acidic - hydrogen peroxide (H₂O₂)induced microwave (AHMW)pretreatment. Higher soluble chemical oxygen demand (SCOD)release of 1450 mg/L and its liquefaction rate of 30.2% was achieved in microwave (MW)pretreatment with treatment time period of 15 mins. Varying concentration of H₂O₂ from 0.003 to 0.03 g/g TS were used in the optimal microwave power (40%)to enhance the organic release in H₂O₂ induced microwave pretreatment (HMW). Maximum liquefaction of 33.9% was obtained at the H₂O₂ concentration of 0.024 g /g TS. The combined HMW pretreatment under acidic (pH 4–6.5)show synergistic effect on organic release. At optimal pH 5, AHMW pretreatment shows the SCOD release of 1850 mg/L with its liquefaction of 38.5% at time of 10 min. Therefore, AHMW pretreatment significantly reduce the treatment time and increase liquefaction when compared to MW and HMW. The maximum biohydrogen production was observed as 92.5 mL H₂/g COD in AHMW pretreatment.