Скачать или смотреть 2021 MSWC Session 7-Jean MacRae, University of Maine

2021 MAINE SUSTAINABILITY & WATER CONFERENCE - 4/1/2021

Session 7 - What contaminants are in our food waste, and can it be safely recycled to circularize the food system?

Jean D. MacRae
University of Maine Department of Civil and Environmental Engineering

A circular food system would reduce the energy intensity of our agricultural system and reduce our reliance on dwindling phosphorus reserves. Diverting food waste from landfill also reduces methane and leachate production, and can stimulate new economic opportunities producing heat, electricity and useful soil conditioners (compost and digestate) from food scraps. While these efforts are positive, we need to be careful to ensure the new pathways don’t introduce new contamination risks into our food system. We measured physical, chemical and biological contaminants in source-separated food waste samples from three states and six source types. We found that heavy metals were rarely detected and when they were, they were below the most stringent global standards for application to soils, so this was not an issue of concern. Halogenated organics were measured using the “bulk” EOX method, which has a high detection limit, but encompasses all of these potentially bioaccumulative pollutants. They were detected in 14% of our samples. A subset of samples were also tested for PFAS. Over half of these contained PFBA, despite removal of visible physical contaminants prior to processing the food waste. The presence of these chemicals in compost or digestate could represent a risk to the system. Another finding of concern was the near-universal detection of tetracycline and penicillin resistance genes (ARGs) in the samples. Most ARGs are located on mobile genetic elements that can be transferred among microbes, and their prevalence in the environment has increased with the use of antibiotics in agriculture, so they are viewed as a risk to infection control therapies. Assessing the risk of these contaminants to a circular food system depends on their fate during treatment, and additional sources during preprocessing.

For more information about the 2021 Maine Sustainability & Water Conference, go to https://umaine.edu/mitchellcenter/202....