Low temperature coupled with mechanical liquefaction of seaweed for energy and economically efficient anaerobic digestion

This current work was focused on energy and economically efficient biogas production from seaweed (marine macroalgae) using low-temperature coupled mechanical pretreatment (LTMP). Low temperature pretreatment (LTP) was performed at 50–90 °C for varying periods, from 0 to 60 min. Maximum soluble chemical oxygen demand (SCOD) of 1040 mg/L with 13 % liquefaction was obtained at 80 °C in 30 min for the LTP process. Disperser was introduced in the LTP optimum conditions for performing LTMP by varying 6000–14,000 rpm in 30 min. Maximum liquefaction of 17 % was obtained with SCOD release of 1360 mg/L at 15 min in LTMP with energy usage of 21,889 kJ/kg TS. This coupled process promotes biomass liquefaction and reduces the treatment time. The biogas production of 238 mL/g COD was produced from the LTMP substrate, which is high compared to control (untreated) and LTP samples. LTMP was an effective pretreatment with 0.9 and $105.25/ton as energy ratio and net profit, respectively. [Display omitted] •Low-temperature coupled mechanical pretreatment (LTMP) improves the seaweed biomass liquefaction and biogas production.•LTMP enhances the liquefaction of about 17 % with the organic's release of 1360 mg/L.•Biogas production of 238 mL/g COD has achieved in LTMP samples.•LTMP is an energetic efficient process with the energy ratio of about 0.9.