DOAS (Differential Optical Absorbance Spectrometry) has been designated as one of the instrumental analyses for the continuous and real time measurement of ammonia and styrene under the newly established Korean Offensive Odor Prevention Law. However, cases of odor monitoring using DOAS are very limited, as questions have been raised relating to its reliability, mainly for ambient monitoring. This paper primarily focused on the advantages and limitations of DOAS for the measurements of ammonia and styrene, with a review of the theoretical and field intercomparison studies, to address its suitability, particularly for odor monitoring purposes. However, this instrumental technique was found to be useful for real time continuous measurements of concentrations over a few ppbv, for both ammonia and styrene, and was also found to be sensitive enough for odor monitoring purposes over vast multi industrial complex regions.

Recently, a bioactive foam reactor (BFR) using a surfactant and suspended microorganisms has been suggested as an suitable alternative to conventional packed-bed biofilters. This study was conducted to demonstrate the feasibility of applying the BFR using styrene as a model compound and investigate the effect of the gas residence time on mass transfer and biodegradation rates. At a gas residence time of 40 seconds, the BFR achieved high styrene removal efficiencies greater than 80%, but the biodegradation rate controlled the overall efficiency as the styrene inlet concentration increased. Meanwhile, at a gas residence time of 20 seconds, the change of the styrene removal efficiency was less sensitive to the inlet styrene concentration, indicating the BFR system was operated under the mass transfer limited condition. Therefore, the mass transfer rate needs to balance with the biodegradation rate in the BFR system, and the foam stability had a significant effect on the mass transfer. In the BFR, the maximum elimination capacity was found to be 117 g/㎥/hr, which was higher than those reported in the literature. This finding indicates that the BFR can be an efficient method for the treatment of various VOCs and expand an application range of biological processes.