Abstract
Food waste generated from restaurants or food stalls needs to be processed correctly to minimise environmental pollution problems. One of the promising methods is pyrolysis process using low-power microwave energy reactor that can convert it into bio-oil. This process is strongly associated with the thermal heating process in a microwave reactor normally indicated by the reaction temperature, heating rate and the thermal efficiency. This work studies the thermal characteristics of microwave reactor during pyrolysis of food waste. A modified domestic microwave oven with a maximum output power of 418 W was used as the experimental reactor in this study. The samples with different moisture content (MC) of 11% and 24% were examined under various microwave power of 257 W, 362 W and 418 W for 1 h. The results showed that the thermal characteristics of microwave were influenced by the microwave powers and moisture contents of the food waste. High microwave power and low MC provide high reaction temperature, heating rate and thermal efficiency. Under investigated conditions, the optimum result was obtained at microwave power of 418 W and MC of 11% in which final temperature, heating rate and thermal efficiency of the pyrolysis process were 757°C, 12.1°C min–1 and 53%, respectively. These results indicated that the modified microwave reactor is capable for pyrolysis of food waste even at relatively low microwave power
Highlights
Billions of tons of waste, municipal solid waste (MSW) are generated annually worldwide
Teflon and copper pipes with a size of 9.5 mm inner diameter were used for transporting volatile substance from refractory reactor to liquid collector generated during pyrolysis process
In order to evaluate the effect of microwave power on the thermal characteristics of microwave reactor consisting of temperature profile, heating rate and thermal efficiency, a series of studies were performed
Summary
Billions of tons of waste, municipal solid waste (MSW) are generated annually worldwide. Because of its high carbohydrate and lipid content, food waste contains more hydrogen and its H/C ratio is much higher than that of other biomasses.[3] These materials can be converted into other forms of energy including gaseous, biodiesel, bioethanol, bio-oil, etc.[4,5,6,7] Pyrolysis has been known as one of the effective methods for biomass processing In this method, the biomass is thermally processed in the absence of air to produce products such as char, oil, combustible gases and valuable chemicals.[8] So far, conventional heating sources such as electric and gas heater is the most used system by the researchers for biomass pyrolysis. Studies on MSW and food waste pyrolysis using microwave reactor have been reported.[8,11] In general, the main used parameters for assessing the yield of products obtained from microwave processing of waste include microwave power, addition of absorber and catalyst, as well as moisture content of the material. With the aim to obtain optimal conditions and achievable technical performance, several parameters including microwave power, irradiation time and moisture content (MC) of food waste were studied
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