A community composting initiative to valorise kitchen biowaste in a Catalan Primary School: Process performance, greenhouse gases and VOC emission analysis.

Composting is a wide-spread technology that allows the stabilisation of many types of organic waste and the subsequent obtention of an organic amendment with valuable fertilising properties for agriculture. In parallel of large-scale composting plants, decentralised composting systems, including house and community composting, have gained interest in recent years as a strategy to manage waste locally and avoid the need of waste collection and transportation in traditional centralised composting systems. In this study, a community composting system consisting of four 1 m³ modules was installed in a primary school and operated for over 130 days treating the biowaste generated in the kitchen and using pruning waste as a bulking agent. The respiration activity of the initial mixture and the final compost was analysed using dynamic DRI (0.6 and 0.3 g O₂ kg^− 1 OM h^− 1, respectively) and static AT4 (21.4 and 6.2 g O₂ kg^− 1 OM, respectively) methods, and the compost produced was characterised. The emission factors for methane (CH₄), nitrous oxide (N₂O), greenhouse gases (GHG, including CH₄ and N₂O) and total volatile organic compounds (VOC) were estimated to be 0.10, 0.14, 41.01 and 1.43 g kg^− 1 VS, respectively. The main VOC and VOC families emitted during the process were also characterised. These values are one of the few emission factors of community composting systems reported in the literature and can be used as a basis to demonstrate the value and efficiency of decentralised composting systems as an environmentally friendly alternative or complement to regular centralised composting facilities.