Ampang Jajar Transfer Station (AJTS) in Pulau Pinang, Malaysia receives wastes from North and Central Seberang Perai, which are consolidated at AJTS before final disposal at Pulau Burung Sanitary Landfill located 40 km south. AJTS is located in an industrial area with the closest residences, Flat Ampang Jajar, about 300 m away. Efforts have been in place to manage odour nuisance by spraying solutions of Effective Microorganism (EM) and Lysol at the operation area of the AJTS. This study was conducted with the objective of verifying the effectiveness of EM and Lysol in odour control and their suitable spraying frequency. Solid wastes taken from AJTS were characterised in the laboratory for solids and moisture content, while its leachate was analysed for chemical oxygen demand (COD) and volatile fatty acids. A portion of the collected sample was also tested for odour concentration with and without EM and Lysol application. Laboratory analysis indicated that AJTS waste is highly degradable with 72% moisture content and 76% volatile solids, thus susceptible to odour production during decomposition. Acetic, butyric and propionic acid were present at concentrations of 3618 ppm, 581 ppm and 549 ppm respectively, higher than their respective odour threshold detection value of 0.21 ppm, 0.001 ppm and 0.16 ppm. The sour and rancid smell attributed with the waste sample is contributed partly by the VFA content. AJTS sample in laboratory conditions was treated more effectively by Lysol (57% odour reduction) compared to EM (24% odour reduction). Lysol reduces malodour by masking the unpleasant “sour garbage” odour with a “soapy” scent instead, leading to a perceived “mildly unpleasant” (–1) hedonic tone. The current spraying of Lysol twice every 6 h at the AJTS is sufficient to manage odour to acceptable
levels for 7 h after spray.