Processing household plastics for recycling – A review

Throughout the household, there are numerous different applications where plastics such as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS) and polyvinyl chloride (PVC) serve a purpose in a superior manner compared to other natural resources. The recycling of these plastics is getting huge attention due to meteoric growth of use which led to significant landfills throughout the world. This research investigates the processes for recycling such as sorting, cleaning, degradation, and reprocessing of household plastics based on the information available in the literature. It was found that the sorting processes including flotation separation, magnetic density separation, melt filtration and spectrometry separation all offer significant potential in various positions along the recycling plant. The magnetic density separation is most efficient and environmentally friendly but relatively expensive separation method. Whilst the cleaning processes are very straightforward where different caustic agents and/or temperature are used with water. These cause thermo-mechanical degradation due shearing, high temperature and cleaning processes. The degraded recycled plastics cannot replace the virgin plastics but those can be reprocessed by blending with the virgin plastics and filler reinforcements to improve the properties. Significant improvement in separation and cleaning process is required to minimise degradation during those processes.