Microwave pyrolysis for valorisation of horse manure biowaste

• Published in: Energy conversion and management 2020-09, Vol.220, p.113074, Article 113074
• Main Authors: Mong, Guo Ren, Chong, Cheng Tung, Ng, Jo-Han, Chong, William Woei Fong, Lam, Su Shiung, Ong, Hwai Chyuan, Ani, Farid Nasir
• Format: Article
• Language: English
• Subjects: Biofuels; Biomass; Biowaste; Calorific value; Carrier gases; Catalysts; Charcoal; Clean energy; Energy; Energy balance; Flow rates; Flow velocity; Fossil fuels; Gas flow; Horse manure; Horses; Manures; Microwave pyrolysis; Phenolic compounds; Phenols; Pyrolysis; Raw materials; Reaction mechanisms; Renewable energy; Sustainability; Synthesis gas; Thermal decomposition
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2020.113074

•Pyrolysis temperature and catalyst loading increase gas yield but lower char yield.•Biochar heating value increases with temperature and catalyst loading.•HHV of 35.5 MJ/kg is recorded for biochar with high surface to pore volume ratio.•Microwave pyrolysis of horse manure produce up to 73.1 vol% of syngas component.•Phenolic compounds constitute the dominant group in bio-oil products.•Lowest energy deficit is achieved at 350–450 °C and even HM:AC ratio. Biomass-based feedstock is an attractive alternative to fossil fuel due to its sustainability and potential as a clean energy source. The present work focuses on the valorisation of horse manure biowaste to produce bioenergy via microwave-assisted pyrolysis technique. The thermal decomposition process is conducted by considering the effects of pyrolysis temperature, catalyst loading and carrier gas flow rate on the yield and quality of end products. The pyrolysed gaseous product contains up to 73.1 vol% of syngas components. The solid biochar obtained contains a heating value of 35.5 MJ/kg with high surface to pore volume ratio. The relatively high specific energy contents of gaseous products and biochar indicate their potential as biofuels. The liquid product is found to contain oxygenated phenolic compound of up to 79.4 wt%. In spite of an overall energy deficit achieved when comparing the total energy of end products with the feedstock, the energy balance analysis indicates the optimum production parameters. The least energy deficit is achieved at the reactive conditions of 350–450 °C and manure-to-catalyst ratio of 1:1. A reaction mechanism pathway for the pyrolysis of horse manure is presented to show the production route for bioenergy and valuable chemicals.