Industrial ecology approach for biodiesel industry in Thailand

Abstract

Due to the Thai government policy to promote use of biodiesel as an alternative for diesel fuel since 2005, the biodiesel production capacity has been continuously increased. Its production process largely consumes both water and energy and also generates wastes and by-product. The objectives of this research were to study waste management in the biodiesel industry and to propose waste management options based on industrial ecology concept, which includes in-plant clean technology and external waste exchange, in order to improve the environmental performance of the industry. Five biodiesel factories that represented for 1-large, 3-medium, and 1-small scale factory were selected to study their production processes, natural resources consumption, wastes generation, and environmental impacts. The waste management options were proposed and analyzed with respect to technical, economic, and environmental considerations. The results from the survey showed that 1 m3 of biodiesel consumes 900 kg of feeding oil, 160 kg of methanol, 10 kg of catalyst, and 0.47 cb.m. of water. Its production process also generates 140 kg of crude glycerin as by-product, 8 kg of spent bleaching earth, and 0.47 cb.m. of wastewater. The appropriate options are reusing the last methyl ester washing water as the first washing water, purifying crude glycerin as pharmaceutical grade, reusing crude glycerin as raw material of other industries such as biomethanol and propylene glycol, and reusing spent bleaching earth in industrial or agricultural sectors. Generated wastewater can be used to produce biogas which is alternative energy for electricity generation