Harvesting and pretreatment techniques of aquatic macrophytes and macroalgae for production of biofuels

Aquatic plants are promising green energy feedstocks owing to their high rate of growth, photosynthesis, and CO2-fixing efficiency. They possess a paramount advantage of non-competitiveness with food crops over the first or second generation biofuel feedstocks. Specifically, low lignin content and higher concentrations of polysaccharides make these plants very attractive for biogas and liquid biofuel production. However, a regular supply of biomass is a limitation that can be overcome by employing harvesting techniques with sustainable measures, which ensure rapid regrowth of biomass for the next cycle. Harvesting of both aquatic macrophytes (weeds) as well as macroalgae is achieved by either manual or mechanical means. Following regular supply through effective harvesting, biofuel production can be further restricted due to their complex structural make-up. In order to improve the biofuel production, various pretreatment methods have been explored to disrupt the complex structure of aquatic weeds and macroalgae, thereby increasing the breakdown of biomass material more readily. This review examines traditional and modern techniques for biofuel production using aquatic weeds and macroalgae. It also discusses recent advancements in the harvesting and pretreatment techniques that improve overall efficiency. Choosing an effective pretreatment method can greatly influence biofuel recovery and production.