A comparative study was conducted for differentiating between attached and suspended growth, represented by a lab-scale biotrickling filter and bio-scrubber under anoxic conditions, respectively. However, malodorous ethane-thiol gas (ET) that was categorized as one of the volatile organic sulfur compounds (VOSCs) was studied using a variety of settings and parameters. In contrast, NO3- can be used as an electron acceptor in the bioconversion of ET gas to elemental sulfur and/or sulfate when no oxygen is available. Empty bed residence times (EBRTs), gas to liquid ratios (G/Ls) (40, 60, 80, 100, 150), and inlet concentrations (150, 300, 800, and 1500 mg/m3) were all investigated in relation to ET removal efficiency (RE) (30, 60, 90, and 120 s). While the G/L ratio of 80 resulted in efficient ET removal (more than 90.8% for 150 mg/m3 of inlet concentration), it could only achieve the extrac-tion of 80.6% for 1500 mg/m3 of inlet concentration at a fixed EBRT of 60 s. These results were based on the performance of a lab-scale anoxic biotrickling filter. Even though mass transfer constraints and poor solubility of ET were factors, the performance of the biotrickling filter under anoxic settings was superior to that of the bio-scrubber and improved the low oxidation rates of ET.