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.

A preliminary study of thermolysis for producing liquid oil from electrical and electronic wastes (e-waste) has been carried out. Various efforts have been made to improve thermolysis process in order to obtain higher yield of liquid oil. The research aims to investigate the effect of temperature and types of e-waste on the yield of liquid oil. A domestic microwave oven was modified and used to produce liquid oil. It was connected with standard condensation unit with water circulating system. Three types of e-waste samples (computer or laptop case, hand phone case and electrical cables/wires) were employed. About 150 g of each samples was thermolysed at 350°C, 400°C and 450°C under nitrogen flow of 0.3 LPM using activated carbon as an absorber and a microwave power of 900 W. The samples were characterised using TGA and ultimate analyser whereas heating value of the optimum liquid product was analysed using bomb calorimeter. This study showed that thermolysis temperature and type of e-waste affect yield of liquid oil. Maximum yields of liquid oil were obtained at 450°C for hand phone case, 400°C for computer case and at 350°C for electrical cables. Among the e-waste studied, hand phone case provided the highest liquid oil yield of 56.2 wt%.

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