Odorous gases are emitted when palm oil mill effluent is treated via anaerobic digestion. Although odour is a nuisance rather than hazardous most of the times, sensory annoyance complaints provoked local authority to seek feasible mitigation. The Department of Environment (DOE) under the jurisdiction of the Air Division has proposed an odour emission limit of 12 000 OUm-3 for Malaysian palm oil mills recently which was found unachievable during previous survey. The objective of this article is to establish the odour concentration (OUm-3) at residential locations close to a palm oil mill and identify ammonia (NH3) and hydrogen sulphide (H2S) gas concentration in odour samples collected from anaerobic ponds. The odour sampling and assessment were performed according to MS 1963:2007 Air Quality – determination of odour concentration by dynamic olfactometry with enhanced VDI3940 Grid Method. Experimental results showed that odour concentrations at residential locations are often dominated by local odour sources such as chicken farms. Odour emission levels at all surveyed residential areas identified as palm oil mills origin were well below 10 OUm-3 most of the times although high level up to 108.4 OUm-3 were observed occasionally due to wind factor. H2S content ranges from 15.9 ppm to 103.9 ppm and NH3 content ranges from 4.1 ppm to 16.6 ppm.
Keywords: odour nuisance, olfactometry, European reference odour mass, ANAEROBIC DIGESTION
*Malaysian Palm Oil Board (MPOB), 6, Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia. E-mail: email@example.com