778 Research Article Received: 7 October 2011 Revised: 23 January 2012 Accepted: 24 January 2012 Published online in Wiley Online Library: 1 March 2012 (wileyonlinelibrary.com) DOI 10.1002/jctb.3762 Influence of the inlet load, EBRT and mineral medium addition on spore emission by Fusarium solani in the fungal biofiltration of hydrophobic VOCs † Alberto Vergara-Fern ´ andez, a∗ Sergio Hern ´ andez, b Ra ´ ul Mu ˜ noz c and Sergio Revah d Abstract BACKGROUND: The effect of the inlet n-pentane load (IL), empty bed residence time (EBRT) and mineral medium (MM) addition on spore emission and elimination capacity (EC) was evaluated using the fungus Fusarium solani in a vermiculite-based biofilter. RESULTS: When the process was operated at an EBRT of 3.7 min and an IL of 100 g m −3 reactor h −1 , the weekly addition of MM from 6.8 to 13.6 mL MM L −1 vermiculite resulted in fluctuacting dynamics of ECs and spore emission. When varying the n-pentane IL from 25 to 875 g m −3 reactor h −1 , a maximum EC of 110 g m −3 reactor h −1 associated with a spore emission of 1.8 × 10 4 CFU m −3 air was recorded. The critical inlet load for 90% n-pentane removal was 50 g m −3 reactor h −1 with spore emission 4.5 × 10 3 CFU m −3 air . Finally, when the EBRT was decreased from 3.7 to 2.1 min at a constant n-pentane IL of 50 g m −3 reactor h −1 the EC decreased by 110%. CONCLUSIONS: The results show a poor performance of the n-pentane biofiltration system at high IL and low EBRT, which was further confirmed by the low final biomass concentrations in the biofilter (62 mg biomass g −1 vermiculite ). c  2012 Society of Chemical Industry Keywords: hydrophobic VOCs; spore emission; Fusarium solani; fungal biofiltration INTRODUCTION The elimination of volatile organic compounds (VOCs) using fungal biofilters has been studied by several authors 1,2,3 because of its advantages over bacterial biofilters. 4–6 Fungal biofilters have the ability to degrade a large number of VOCs, resistance to low humidity and pH, 7,8 the capacity to colonize empty space with aerial hyphae increasing the transport area and can penetrate the solid support favoring the availability of nutrients. 4 Fungal biofilters also have some disadvantages including the potential emission of spores. 9–11 Studies on the emission of microorganisms from biofilters have included the evaluation of both bacteria and fungi. Ot- tengraf and Konings 12 reported the emission of microorganisms (10 3 –10 4 CFU m −3 air ) from biofilters during VOCs treatment. Like- wise, Zilli et al. 13 monitored the emission rate of airborne bacteria during benzene biofiltration in biofilters packed with peat and sieved sugarcane bagasse, and operated with different micro- bial cultures (allochthonous and autochthonous bacteria). The airborne bacteria concentration in the outlet of these biofilters ranged from 1.0 to 4.0 × 10 3 CFU m −3 air , which was slightly higher than in the ambient air. Sanchez-Monedero et al. 14 evaluated the performance of biofiltration as a method to control spore emis- sion from Aspergillus fumigatus and found that the concentration after the biofilter was lower than 1.2 × 10 3 CFU m −3 air . Despite the relevance of spore and bacteria emissions from biofiltration facili- ties, little research has been devoted to this issue. Therefore, more research is needed to understand and control the mechanisms of spore emission from biofilters. In this context, the nutrient (mineral medium, MM) content of the packing materials and its bioavailability play an important ∗ Correspondence to: Alberto Vergara-Fern´ andez, Centro de Energ´ ıasRenovables y Calidad Ambiental, Escuela de Ingenieria de Procesos Industriales, Facultad de Ingenier´ ıa, Universidad Cat´ olica de Temuco, Rudecindo Ortega 02950, Campus Norte, Casilla 15-D, Temuco, Chile. E-mail: avergara@uctemuco.cl † Presented at the IVth International Conference on Biotechniques for Air Pollution Control (Biotechniques-2011). a Centro de Energ´ ı as Renovables y Calidad Ambiental, Escuela de Ingenieria de Procesos Industriales, Facultad de Ingenier´ ıa, Universidad Cat´ olica de Temuco, Casilla 15-D, Temuco, Chile b Departamento de Ingenier´ ıa de Procesos e Hidr´ aulica (IPH), Universidad Aut´ onoma Metropolitana-Iztapalapa, M´ exico D.F., M´ exico c Departamento de Ingenier´ ıa Qu´ ımica y Tecnolog´ ıa del Medio Ambiente. Universidad de Valladolid, 47011 Valladolid, Spain d Departamento de Procesos y Tecnolog´ ıa, Universidad Aut´ onoma Metropolitana-Cuajimalpa, M´ exico D.F., M´ exico J Chem Technol Biotechnol 2012; 87: 778–784 www.soci.org c  2012 Society of Chemical Industry