PYROLYSIS PROCESS STUDIES FOR POST CONSUMER POLYETHENE WASTE CONVERSION AND UPGRADING OF THE PYROLYSIS OIL

Abstract

Pyrolysis is a waste to energy conversion technology that operates in oxygen free environments. Pyrolysis can be applied in the sustainable management of plastic wastes through conversion to liquid and gas fuels which are chemically similar to fossil fuels. This study was carried out to implement a suitable and cost-effective recycling technology that will help solve severe pollution problems resulting from poor management of waste plastics in urban and rural set-ups in Kenya. The paper aims to conduct pyrolysis process studies for post-consumer polyethene waste conversion and characterization of the resultant liquid products. This was conducted in a locally assembled pyrolysis reactor at temperatures ranging between 200 to 350 °C for periods 1 to 2 hours. Low Density Polythene (LDPE), High Density polythene (HDPE) and Polypropylene (PP) were used in the experiments. Plastic waste materials were collected from the open dumpsites, washed, sun-dried, sorted out according to resin codes, sliced and pelletized into small pieces of dimensions of 2 mm. The samples were feed in the preheated reactor for conversion and the liquid collected in glass jars. Fractionation was conducted to partition the crude into petrol at 150 oC and diesel at 350 oC. HDPE, LDPE and PP produced 720±1.64, 696.07±1.67 and 602.08±2.01 ml of crude oil for 1 kg of wastes respectively. Diesel yield was 72%, 70% and 60% for HDPE, LDPE and PP respectively while petrol was 6%, 8% and 6% respectively. HDPE, LDPE and PP produced 1 %, 5 % and 1 % of solid residue respectively. The results showed that over 90% conversion of plastic waste into fuel products is achievable through pyrolysis process.