This study investigates odour removal of pilot-scale biofilters treating volatile organic compounds (VOCs) produced during composting of organic fraction of municipal solid wastes (OFMSW). Four biofilters, containing non-biodegradable zeolite, biodegradable coir fibre, and the mixture of both materials, with and without inoculum, were set up onsite to treat the exhaust gases from a local composting facility. Odour-removal efficiencies of the biofilters were monitored by sensory concentration measurement using olfactometry and analytical measurement using gas chromatography-mass spectrometry (GC-MS) on three occasions, at start-up, 3 months and 9 months of operation.
At feeding rate of 1 L/L/min and feed concentration of 9,000-10,000 OU, odour removal efficiencies of the biofilters were over 90% right from start up through to 9-month period of monitoring. Inoculation of biofilter was found to be beneficial but not essential. Based on detailed analysis of odour compounds using GC-MS, zeolite biofilter was effective in adsorbing polar compounds (such as alcohol and volatile acids) while coir biofilter was found to be particularly effective in capturing non-polar VOCs, such as monoterpenes (the main component in the feed stream). The combination of coir and zeolite complemented one another providing very effective removal of both polar and non-polar volatile compounds
