Sustainable enhancement of biogas and methane yield of macroalgae biomass using different pretreatment techniques: A mini-review

Abstract

Macroalgae can be grown without the use of fertilizer, fresh water, or arable land. These qualities support its use for biofuel production because it frees up land for other traditional energy sources and food crops. It has been investigated as biogas feedstock to substitute for fossil fuels burning with attendant effects on the ecosystem. The microstructural arrangement of macroalgae biomass is restricting their conversion to biogas. Therefore, application of pretreatment before anaerobic digestion is needed to enhance their availability to microbial degradation and subsequent increase in biogas yield. Pretreatment application for substrate catalysis is vital to recovering eco-friendly and economical energy from macroalgae. This study summarizes the state of the art of various pretreatment methods employed to enhance macroalgae biomass's anaerobic digestion process. These methods were categorized as thermal, biological, chemical, nanoparticle additives, mechanical, and combined. Merits and challenges associated with each of these methods were also considered. The study shows that all the pretreatment methods considered can improve the biogas yield if the appropriate method is selected based on the type of macroalgae species. Pilot-scale studies that will assist in assessing their feasibility on the full-scale implementation are still missing.