Aquatic weed as a biorefinery resource for biofuels and value-added products: Challenges and recent advancements

Aquatic weeds have posed a challenge in their containment to halt its spread worldwide. When removed from the water systems, huge capital and human resources are diverted for its safe management and disposal. When used as a potential resource, the aquatic weeds can be profitable and beneficial. The contents of carbohydrate, protein and lipids make aquatic weed a potential feedstock in production of biofuels. Lignin and sugar component of aquatic weed could be utilized in production of bio-oil, combustible gases and heat energy using thermochemical methods. The sugar portion could be subjected to fermentation to produce bio-ethanol, bio-methanol and bio-butanol. The lipid fraction of the aquatic week could be utilized to produce biodiesel. Bio-methane and bio-hydrogen could also be developed from the biomass of aquatic weed by biological processes. A large-scale production of aquatic weed will be feasible with innovative and cost-effective methods for harvesting, drying, transportation of the aquatic weed to processing sites and conversion to respective biofuels. Process intensification (viz. Microwave and sonication) during pretreatment steps could fasten the decomposition of biomass of aquatic weed.A biorefinery approach where the aquatic biomass could yield biofuel, fertilizer, industrially useful chemicals and remediate the wastewater is ought to make the overall process economical, sustainable and environment friendly. The value-added products (enzymes and polymers) derived from the biomass of the aquatic weeds could strengthen the commerciality of the process. Aquatic macrophytes could further be used in food source for animals, fish, and humans; in paper making and in medicinal applications.