Multivariate optimisation study and life cycle assessment of microwave-induced pyrolysis of horse manure for waste valorisation and management

Abstract

The increasing amount of waste generated globally due to industrialisation and economic activities require a proper and efficient waste management route. Turning waste to energy via pyrolysis pathway is a promising solution to reduce the amount of waste while generating useful end products. In the present study, microwave pyrolysis of horse manure for the production of bio-fuels and bio-chemicals is conducted and optimised using a lab-scale reactor. Pyrolytic products derived from optimised parameters show that the energy density of bio-char increased by 38.7% with a surface area of 799.57 m2g-1. The bio-oil was found to be enriched with phenolic content while the gaseous product contained high syngas proportion (67.17 vol%). A life cycle assessment (LCA) on the microwave pyrolysis of horse manure for a modelled pyrolysis plant located in Peninsula Malaysia has been conducted to evaluate the energy consumption, operation cost and environmental impact of each unit processes involved. Processing of horse manure via microwave-induced pyrolysis is demonstrated to be more advantageous as compared to the conventional pyrolysis of swine manure from the aspects of higher conversion efficiency, lower energy consumption and reduced environmental risk. Overall, the LCA of horse manure on microwave pyrolysis shows positive environmental impact as compared to other biowaste treatment methods such as composting and incineration.