A biological oxidizer is a device that uses micro-organisms to treat wastewater and the volatile organic compounds produced by commercial and industrial operations. Biological oxidation devices convert biodegradable organic compounds into carbon dioxide and water. This is a natural occurring process which differs from traditional chemical and thermal oxidizing agents and methods. Some of the more commonly used micro-organisms are heterotrophic bacteria, which play an important role in biological degradation processes. Generally, these micro-organisms are rod shaped and facultative. Biological oxidizers provide a stable environment which allows bacteria to naturally oxidize and stabilize a large number of organics in a more efficient manner. Some of the emissions that may be treated biologically include: heterocyclic compounds (such as quinoline or pyridine); polyaromatic hydrocarbons (PAHs); pharmaceutical substances; polychlorinated biphenyls; hydrocarbons (oil); benzene, toluene, ethylbenzene, and xylene (BETEX); methyl ethyl ketone (MEK); some metals. The prompt removal of a wide range of wastes and pollutants from the environment is the foremost requisite leading to minimal negative environmental impact and sustainability. Microorganisms offer excellent anabolic and catabolic adaptability to degrade and produce stabilized organic matters from contaminants. Microbiology is providing significant views of regulatory metabolic pathways as well as effectiveness to adaption and biological degradation in our changing environment. Biological destruction mechanism of hazardous air pollutants Micro-organisms are utilized in biological remediation to control industrial and commercial vapor effluents. When utilizing biological oxidation systems for the remediation emissions, the off gases or vapors are passed through a packed bed having a thin biological film at the surface. The micro-organisms are immobilized into the thin biological film, as the vapor passes over the film they become attached and are oxidized or stabilized. The biological film accomplishes the degradation process, as the biological sump water is reprocessed over the biomedia it creates additional biological growth and as the film increases so does the biological oxidizers efficiency. Large surface area and footprint were once required to treat waste water vapor and industrial plant emissions, with the advent of advanced biological oxidation equipment a smaller footprint is required. The footprint will typically occupy the same space as conventional thermal oxidizers. Biological controls Excessive formation of the biological film may lead to certain problems such as sloughing, it is an important factor to maintain optimum biological film. Maintaining the biological film is accomplished by proper moisture content. For this purpose the humidity of the air is adjusted within the