Resource recovery is being encouraged by regulators in Australia. This has led to proposals for reuse of a wide range of different types of organic wastes. Such wastes include biosolids and composts but also organic wastes from general kerbside garbage or food waste.
Such wastes contain a wide range of chemicals so careful assessment of the characteristics of these materials, any processing methods and how they are applied (application rates, number of rounds of application) is needed to ensure sustainability of this rapidly growing industry.
Detailed risk assessments have been undertaken for a range of different waste types. These calculations have used standard methods but have required reviews of the literature to determine appropriate values for a wide range of parameters including chemical characteristics, uptake factors into fruits, vegetables, crops and livestock.
Criteria to determine if materials are of acceptable quality for resource recovery were back calculated to give an acceptable risk as defined in national guidance in Australia.
The approaches have been applied to a range of waste types and groups of chemicals. Regulators have made use of the assessments to set policy and to make regulatory decisions for specific sites.
The approaches will be presented along with the challenges which include variability of chemical concentrations in the wastes and obtaining robust values for critical parameters.