The ISWA Working Group on Biological Treatment of Waste released the “Practitioner’s Guide to Preventing and Managing Contaminants in Organic Waste Recycling
Authored by Dr Jane Gilbert and Dr Marco Ricci-Jürgensen, this ISWA guide provides background information and case studies about the different types of contaminants (physical, chemical and biological) that can enter organic waste streams intended for recycling, their potential impacts and the ways in which they can be prevented or removed.
Its section on managing contaminants provides a contaminant management hierarchy, contaminant removal costs, health and safety considerations, and a subsection about HACCP and its relevance. Preventing contamination is prioritised and its section on this covers collection schemes, public awareness initiatives, product bans and restrictions and differential gate fees. The topic of removing or eliminating physical contaminants is split into: physical contaminants, separation techniques and associated factors; chemical (organic and inorganic) contaminants; biological contaminants; and an appendix provides practical examples of contaminant removal at four organics recycling facilities, outlining specific steps that eliminate or divert contaminants from the main process flow. ‘As contaminants threatens to impair recycling processes and reduce product quality, it is essential that they be prevented and removed effectively’, says ISWA.
Therefore, they call for; investment in R&D to improve contaminant removal techniques whilst minimising organic matter dragged out with contaminants, contracts that set maximum contamination levels and specify a variable gate fee depending on the level of contamination in the load received, prioritised organic waste collection schemes that enable identification of contaminated loads and feeding this back to individual waste producers, and investment in regular information campaigns aimed at raising citizens’ awareness of the importance of maximising the quality of organic waste for recycling.