Experimental Investigation on the Treatment of Mixed Market Waste by a Novel Rotary Air Dryer

Abstract

In the present study, the market wastes were treated and made as fine briquettes by using a portable rotary dryer. For the experimental purpose, a portable rotary dryer was designed and developed to determine the drying conditions of market waste. A U-type electric air heater of 1000 W were installed in the heating unit along with solar parabolic dish collector. The input parameters for the experiments are drying temperature (120 °C), rotation of dryer (3 rpm), air velocity (5 m/s), initial residue temperature (30 °C) and residue bulk density (200–250 kg/m3). Mixed market wastes are in the proportions such as: Briquette 1: watermelon lund 40% + drumstick pods 10% + beans pods 30% + drumstick peels 20%, briquette 2: watermelon lund 30% + drumstick pods 30% + beans pods 20% + drumstick peels 20%. The final product resulted in fiber form, which can be compacted to an even size of fuel briquettes which can be directly used for commercial and domestic heating. The performance of rotary dryer was analyzed based on inner rotary drum depth position (z = 0 m, z = 0.25 m, z = 0.5 m) and drying time (up to 150 min). The performance parameters like variation in moisture ratio, drying temperature, dry air humidity and air temperature were investigated in the present study. Residence time required for drying the mixed market waste up to milling moisture content (< 20%) in the developed dryer takes 150 min, while the sun drying takes 12–14 h generally. Calorific value of the fuel briquettes produced in the study is determined as 16.2–17.8 MJ/kg. The developed rotary air dryer provides a promising alternative to landfilling because of its low cost of construction, easy operation, green energy utilization and portability.