Food waste and the plastic covers used for packing medical items are big sources of land pollution. In this study food waste has been converted into biogas. This biogas is used as a heating agent to crack the non-recyclable waste plastic covers, made up of LDPE, into liquid hydrocarbons in a reactor using lignite fly ash as catalyst. The cat/pol ratio used in this work is 0.1. This cracked vapour is condensed in air and water cooled condensers to separate high and low boiling liquid hydrocarbons. In this work, 25 kg of food waste is converted into 4.5m3 of biogas. This biogas is used as fuel for cracking 0.5 kg of plastic made of LDPE using 50 g catalyst. The conversion of waste plastic into hydrocarbons is 100%. The amount of biogas consumed was 2.5m3. The waste plastic oil (WPO) obtained after the cracking was 266 g (53.2%). The amount of gasses hydrocarbon is 234 g (46.8%). The amounts of low and high boiling fractions were 24.8% and 28.4%, respectively. The physical and chemical properties of these fractions have been determined.