Comprehensive performance and critical components of odours at food waste composting plants

The current government policy toward food waste management encourages composting for resource recovery. Malodourous emissions from these composting plants impact on ambient air quality and health. This study used olfactometry, gas chromatography- mass spectrometry (GC-MS) and gas detector tubes to evaluate the ambient air at three of the largest food waste composting plants in Taiwan. Ambient air inside the plants, at exhaust outlets and plant boundaries was examined to determine the comprehensive odour performance, critical components, and odour elimination efficiencies of various odour control engineering. Analytical results identified 29 compounds, including ammonia, amines, acetic acid, and multiple volatile organic compounds (VOCs) (hydrocarbons, ketones, esters, terpenes and s-compounds) in the odour from food waste composting plants. Concentrations of six components - ammonia (1,263±3 μg/m ³), amines (5,911±14 μg/m³), dimethyl sulfide (759 μg/m³), acetic acid (612 μg/m³), ethyl benzene (11±10 μg/m³), and p-Cymene (67±11 μg/m ³) - exceeded human olfactory thresholds. Ammonia, amines, dimethyl sulfide and acetic acid accounted for most odours compared to numerous VOCs. A biotrickling filter was better at eliminating the concentrations of odour, NH₃, amines, S-compound and VOCs than a chemical scrubber and biofilters. All levels measured by olfactometry at the boundaries of food waste composting plants (range, 74-115 Odour Concentration (OC)) exceeded Taiwan's EPA standard of 50 OC. This study indicated that the malodour problem continues to be a significant problem for food waste recovery.