Toluene removal by biofiltration:: Influence of the nitrogen concentration on operational parameters

The study presented in this paper dealt with the operation of a laboratory-scale upflow biofilter, packed with compost-based filter material. The airborne contaminant studied was toluene, maintained at a constant inlet concentration of 1.7 g(.)m(-3). The input air was conveyed upward through the filter column at a flow rate of 1 m(3.)h(-1). The objective of this work was the study of the impact of increasing concentrations of nitrogen contained in the nutrients solution and, hence, the establishment of a new correlation between this parameter and the overall degradation performance. Depending on the nitrogen concentration employed, two biodegradation regimes have been identified. Over the optimal range of nitrogen concentrations [2.0-8.0 g of (NL-1)-L-.], the maximum level of elimination capacity achieved was similar or equal to 100 g(.)m(-3.)h(-1). This value is in line with theoretical considerations that suggest that an optimal nitrogen concentration of similar or equal to2.6 g of (NL-1)-L-. is required to achieve the same performance (100 g(.)m(-3.)h(-1)).