Implementing circular economy concept by converting cassava pulp and wastewater to biogas for sustainable production in starch industry

Abstract

Adoption of the circular economy concept to utilize wastes and by-products from the cassava starch industry for biogas production has been considered a viable option. The annual generation of wastewater and cassava pulp in Thailand is reported to be approximately 21 million m3 and 9.5 Mt, respectively. This research therefore aimed to analyze the key drivers and challenges in implementing the circular economy concept in the cassava starch industry in order to generate higher demand for biogas systems, increase the energy security and resource efficiency, and combat the environmental problems associated with cassava wastes. The following three scenarios were analyzed in this study: (1) a factory without integrated biogas system, (2) a factory with integrated biogas installation using wastewater as a raw material, and (3) a factory with biogas system using both wastewater and cassava pulp as raw materials. The assessment of economic feasibility, resource efficiency, water recovery, land use, and global warming potential was performed to compare different scenarios. This study found that Scenario 3 generated the highest net present value and the shortest payback period of 6.14 million USD and 4.37 yr, respectively, for the 10-yr operational period. Moreover, Scenario 3 had the highest resource efficiency and water recovery with the lowest land use (1.89 × 105 m2 at 5 × 105 kg of starch d− 1) and the lowest global warming potential (0.14 kg CO2eq kg− 1 of starch). © 2021, The Author(s).