The development and spread of mechanical biological treatment (MBT) and composting plants is often hindered by the problems and concerns arising froth emission bad odors. Several technologies are now available to process exhausted air originated from these or similar plants. Exhausted air emissions contain a large amount of organic compounds. most of them in very low concentrations. This determines the advantage in using biological abatement systems (biofilters) instead of physical-chemical treatments. This article describes the operative results obtained in two Italian waste treatment plants, one in Albano, near Rome, and the other in the "ex-Maserati area" of Milan, including (i) the analysis of operational parameters as temperature, pH, humidity, loss of pressure of the biofilter affecting the biofiltration efficiency, for both chemical parameters and odorous compound concentration; measured by means of odor panel evaluation technique and (ii) the efficiency of the biofiltration system for several compounds present in air emissions, analyzing organic substances by means of gas chromatography/mass spectrometry. The two plants used similar biofiltration systems except for the material used as biofilter bed. A bioscrubber pretreatment of the air flow coining froth the aerobic reactor was tested in the Albano plant for the purpose of reducing the odor concentration of the most impacting flow going to the biofilter.
