Environmental Impact Assessment and Process Upscaling for Sustainable Production of Cellulose Nanofibre, a Biopolymer Derived from Lignocellulosic Biomass

Abstract

As an agricultural waste, rice straw has a requisite quality for conversion to nanocellulose; however, the environmental and technical feasibility of the processes available has not been assessed at commercial scale. Therefore, in the present work commercialization and environmental impacts of the cellulose nanofibre (CNF) production from rice straw were evaluated by scaling up the laboratory-scale process to the pilot scale level. Life cycle assessment (LCA) of the laboratory scale process showed the maximum impact of electricity (161 kg CO₂ eq) and sodium hydroxide (7.82 kg CO₂ eq) on global warming potential; though, the overall impacts got reduced approximately three times (~51 kg CO₂ eq for electricity) with the scale-up of the process. When compared with the reported literature both the scales of production were found to have lesser environmental impacts. Further, the techno-economic feasibility of the process was evaluated at different plant capacities for the optimum minimum selling price (MSP) of CNF. At the plant capacity of 15 kg/day, the MSP of CNF was calculated as $16,537.36/tonne dropped to $14,944.87 and $14,590.98/tonne with the increased batch capacity of 30 kg/day and 45 kg/day, respectively. Through sensitivity analysis, the MSP of CNF was observed to be highly sensitive to the cost of capital investment and chemicals cost. In addition, analysis of the uncertainty associated with the identified cost drivers reflects the scope for inherited risks, as determined by the Monte-Carlo simulation method. This study established an environmentally and economically sustainable process for commercialisation of nanocellulose production from agricultural waste at a minimum cost of production.