Australia currently produces more than 40 Mt of organic waste each year, including food and garden organics (20%) and biosolids (10%). All organic wastes can be recycled for beneficial reuse, including for soil productivity, although only about half of these materials are reused. Organic waste reuse forms an important part of Australia’s expanding circular economy, although this needs to consider not only social and economic benefits but also minimising potential environmental impacts. The source and nature organic wastes means they often contain contaminants that may enter the environment following reuse. One such contaminant of emerging concern are plastics, which are widespread in many environmental compartments due to their common use in modern societies.
An overview of our research on plastics in various organic wastes will be given here. This will include methodology developed for the analysis of microplastics in complex organic matrices such as biosolids using a microscope combined with Fourier Transform Infrared Spectroscopy (FT-IR) for relatively rapid and reliable quantification and characterisation of microplastics. Additionally, we have assessed how plastics present in waste streams can affect the fate of other contaminants, including trace metal and organic contaminants, also present in waste streams. Also, a summary of terrestrial organism effects assessments of plastics in organic wastes will be given, for both commonly used, poorly degradable plastics and plastics designed to degrade within organic wastes i.e. compostable plastics.
This will help to identify where future research may be required for plastics in organic waste materials, especially as their reuse is anticipated to continually increase in the near future.