Top: Graphic courtesy Compost Research & Education Foundation

Composting facility operators can be challenged by compost overs that are contaminated, especially with plastic. Unlike clean screened overs — which typically are recycled back into the beginning of the composting process as an inoculant — contaminated overs require additional materials handling in order to utilize them. They also can occupy valuable space at the composting site and be a source of pile fires if not carefully managed. A Compost Research & Education Foundation webinar on March 6, 2025, “The Compost Overs Challenge: Is Biochar An Answer,” explores solutions to this challenge. The speakers, Tim O’Neill, ECS, David Drinkard, Qualterra, and Brendan Harrison, Lawrence Berkeley National Lab, will cover the pluses and minuses of using contaminated overs to make biochar, and discuss the use of biochar in the composting process. Harrison will also cover how biochar could influence greenhouse gas and air pollutant emissions during composting and explain desirable characteristics of biochar for cocomposting.