**6. Conclusions**

Lignocellulosic biomass has a huge potential for biogas production, which would be a sustainable alternative for nonrenewable fossil fuels. Upon optimization of lignocellulosic biomass delignification, high rate of biomethanation would be a possible feasible solution to fill previous research gaps without using costly fermentable sugars from food sources. Most importantly, having a clearer understanding on biomass characteristics before and after pretreatment will provide information about storage of delignified feedstock, which is key point for saving renewable biomass in order to meet energy demand of future generation before it gets exploited like fossil fuels. Later, presenting the CO2 biocapture by selective algal strain could reduce cost associated with conventional chemical CO2 scrubbing technologies and could be a breakthrough with potential applications. In addition, algal flocculant chitosan can be extracted from shrimp waste, which will be cost-effective for harvesting and dewatering of algal biomass by means of circular bioeconomy. It is most important to achieve ~100% harvesting of microalgal biomass with chitosan under optimal physiochemical parameters associated with flocculation approach. Polysaccharides and oils recovered from dewatered algae can adapt as lightweight, waterproof biodegradable plastic material, and organic fertilizer to enrich crop yield. However, more research on anaerobic digestion of lignocellulosic biomass coupled with algal systems could be useful to commercialize biogas production from widely produced low-cost substrate, and cultivation of algae in parallel for CO2 mitigation results in top-value chemical generation with home-grown technology.

*Biogas - Recent Advances and Integrated Approaches*
