Improving hexane removal by enhancing fungal development in a microbial consortium biofilter

Abstract

The removal of hydrophobic pollutants in biofilters is often limited by gas liquid mass transfer to the biotic aqueous phase where biodegradation occurs. It has been proposed that the use of fungi may improve their removal efficiency. To confirm this, the uptake of hexane vapors was investigated in 2.6-L perlite-packed biofilters, inoculated with a mixed culture containing bacteria and fungi, which were operated under neutral or acid conditions. For a hexane inlet load of around 140 g.m-3.h-1, elimination capacities (EC) of 60 and 100 g.m-3.h-1 were respectively reached with the neutral and acid systems. Increasing the inlet hexane load showed that the maximum EC obtained in the acid biofilter (150 g.m-3.h-1) was twice greater than in the neutral filter. The addition of bacterial inhibitors had no significant effect on EC in the acid system. The biomass in the acid biofilter was 187 mg.g-1 (dry perlite) without an important pressure drop (26.5 mm of water.m-1reactor). The greater efficiency obtained with the acid biofilter can be related to the hydrophobic aerial hyphae which are in direct contact with the gas and can absorb the hydrophobic compounds faster than the flat bacterial biofilms. Two fungi were isolated from the acid biofilter and were identified as Cladosporium and Fusarium spp. Hexane EC of 40 g.m-3.h-1 for Cladosporium sp. and 50 g.m-3.h-1 for Fusarium sp. were obtained in short time experiments in small biofilters (0.230 L). A biomass content around 30 mg.g-1 (dry perlite) showed the potential for hexane biofiltration of the strains.

Biofiltration of gasoline and diesel aliphatic hydrocarbons

“…Cladosporium degraded both aromatic hydrocarbons (Weber et al, 1995;Kennes and Veiga, 2004) and C 6 -C 19 n-alkanes (Cofone et al, 1973;Arriaga and Revah, 2005a). Paecilomyces variotii and Paecilomyces variotii formerly classified as Scedosporium apiospermum degraded toluene (García-Peña et al, 2001;Aizpuru et al, 2005).…”

Start-up and performance characteristics of a trickle bed reactor degrading toluene

“…In the following 32 days of operation, the system was loaded by the air flow rate with a constant toluene inlet concentration of 100 mg.m -3 (Fig. 3) (Morales et al, 1998), compost (Delhomenie et al, 2003, vermiculite (Ortiz et al, 2003), perlite (Arriaga and Revah, 2005), activated carbon (Li et al, 2002 . Therefore, an EBRT of 35s was the optimal value for this system, with respect to sufficient air cleaning at a good elimination capacity of 7.5 g C .m…”

Aislamiento e identificación de levaduras degradadoras de hidrocarburos aromáticos, presentes en tanques de gasolina de vehículos urbanos

“…Estos microorganismos tienen la capacidad de transformar mediante complejas estrategias metabólicas sustancias contaminantes como hidrocarburos, cuya presencia, en un ambiente con disponibilidad de agua y minerales, les provee un entorno que permite su desarrollo y crecimiento. Según Prince (2010), más de 150 géneros de bacterias contienen especies capaces de crecer con hidrocarburos como única fuente de carbono y energía, pero sólo unos pocos hongos y algas han sido estudiados (Markovetz et al, 1968;Walker et al, 1975;Prenafeta-Boldú et al, 2001;Arriaga & Revah, 2005;Yemashova et al, 2007;Cerniglia y Sutherland, 2010). Sin embargo, se ha descubierto que ciertos hongos filamentosos poseen mecanismos para biodegradar estos compuestos, particularmente hidrocarburos aromáticos policíclicos (PAH por sus siglas en inglés) (Cerniglia & Sutherlan, 2010).…”