Abstract
Environmental pollution due to the consumption of non-renewable energy lead the search for alternative eco-friendly renewable fuel. The study details the biohydrogen production efficiency by potential macroalgal (Ulva reticulata) biomass improved by a disperser combined with calcium hypochlorite pretreatment technology. Calcium hypochlorite was added to decrease the surface energy of the medium induced by sole disperser pretreatment. Optimum condition for algal disperser treatment was 10,000 rpm with 30 min as dispersion time. The specific energy spent for the disintegration of the macroalgal biomass was 1231.58 kJ/kg TS. COD solubilization rate of 11.79% was attained with mechanical pretreatment whereas increased to 20.23% with combined pretreatment. Combination of disperser with calcium hypochlorite significantly reduced the specific energy input spent to 500 kJ/kg TS. The amount of organic materials such as carbohydrates, proteins and lipids released were 680 mg/L, 283 mg/L and 136 mg/L respectively. Thus, the combinative pretreatment with disperser rotor speed (10,000 rpm) for pretreatment time (12 min) and calcium hypochlorite dosage (0.1 g/g) derived as optimum condition for effective solubilization of macroalgal biomass. Biohydrogen production potential was maximum in the macroalgae pretreated with both disperser and calcium hypochlorite recorded highest yield (54.6 mL H2/g COD) compared to the macroalgae pretreated with disperser alone (31.7 mL H2/g COD) and untreated macroalgae (11.5 mL H2/g COD).
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•Disperser combined with calcium hypochlorite on macroalgae to produce biohydrogen.•Optimal condition of disperser at 10,000 rpm and Ca(OCl)₂ dose of 0.1 g/g for 12 min.•Specific energy input reduced to 500 kJ/kg TS to achieve 20% solubilization.•Maximum biohydrogen production of 54.6 mL H2/gCOD was recorded.