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).
Highlights
Application of the circular economy (CE) concept to wastes and by-products from the cassava starch production process (CSPP) can lead to sustainable development, higher economic profit and more efficient resource usage through waste minimization, as well as environmental benefits [1, 2]
A systematic methodology to use wastewater and cassava pulp for biogas production in the starch industry was proposed in order to compare the benefits of CE concept implementation in the CSPP using cassava pulp and wastewater for biogas generation among different scenarios
Analysis of water consumption and wastewater generation For each 1000 kg of cassava starch produced, the water consumption in the CSPP was in the range of 9.8 to 62.1 m3
Summary
Application of the circular economy (CE) concept to wastes and by-products from the cassava starch production process (CSPP) can lead to sustainable development, higher economic profit and more efficient resource usage through waste minimization, as well as environmental benefits [1, 2]. Wastes from the CSPP typically consist of 600 kg of rhizomes, 170 kg of sand, 100 kg Lerdlattaporn et al Sustainable Environment Research (2021) 31:20 of cassava peels, 2500 kg of wet pulp, 8.4 m3 of wastewater, and 4.0 kg of low-grade starch [5]. The remaining wastewater from the CSPP is used to produce biogas to generate heat or electricity, which can be used in the manufacturing process with surplus electricity being sold to the grid. In 2019, Thailand produced approximately 260.7 million Nm3 of biogas from native starch wastewater from 62 biogas plants [5]
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