Biofiltration technology was experimented with in the 1950s in the United States and Europe, but was largely ignored in the United States while being successfully commercialized in Western Europe. Hundreds of biofilters (quite possibly nearing 1,000) are currently in operation in western Europe, while North America has fewer than 75. Applications vary, but have often been on odorous emission sources in Europe, where population density and proximity to residences created nuisance situations. Biofilters proved more than adequate to handle these odor applications, were lower in capital cost and more cost effective in operation and maintenance than conventional thermal oxidizers or chemical scrubbers. Europe was also less concerned with general control of VOCs, as ground level ozone was not a major issue. European countries did not require strict VOC control to the levels often mandated by the U.S. EPA. Therefore, the use of biofilters in Europe moved forward because they solved the odor problems, were not as costly as other controls (capital and operational), and generally did not have to meet exacting emission removal efficiencies that had been or were proposed in the United States.
In North America, the demands of relatively high (often exceeding 95% destruction efficiency, or “Dre”) removal efficiency regulations created difficulties for the use of biofilters as Best Available Control Technology (BACT) and Maximum Achievable Control Technology (MACT). Industries could not afford to chance a relatively unproven biological system for their main pollution-control device, as the established thermal oxidizers and chemical scrubbers gave them security from non-compliance with regulations, and their own emission limits and air-pollution control permits. In addition, the laws and regulations previously established for various industry emissions were not enacted with biofilter systems in mind. Energy was abundant and inexpensive, so conventional (available) thermal and chemical technologies were the only consideration. Control of the volatile organics was paramount, and the fact that thermal oxidizers produced additional NOx and considerable additional amounts of CO2 and some CO from the combustion of fossil fuels was not a significant issue.