Research article Methane production from a field-scale biofilter designed for desulfurization of biogas stream Mateus Pirolli a ,M  arcio Luís Busi da Silva b, * , Melissa Paola Mezzari c , William Michelon a , Jean Michel Prandini a , Hugo Moreira Soares a a Department of Chemical Engineering, Federal University of Santa Catarina, Florian opolis, SC 88040-900 Brazil b EMBRAPA Swine and Poultry, P.O. Box 321, Conc ordia, SC, 89700-000 Brazil c Biotechnology and Sciences Program, West University of Santa Catarina, Videira, SC 89560-000 Brazil article info Article history: Received 30 December 2015 Received in revised form 18 February 2016 Accepted 7 April 2016 Keywords: Biodesulfurization Biotrickling filter Hydrogenotrophic Methane RT-PCR abstract The development of a simple and low maintenance field-scale biotrickling filter (BTF) for desulfurization of swine wastewater-derived biogas stream that was also capable of increasing biomethane concentra- tions was investigated. BTF was continuously fed with wastewater effluent from an air sparged nitrification-denitrification bioreactor installed downgradient from an UASB-type digester. BTF maximum removal efficiency (RE) of 99.8% was achieved with a maximum elimination capacity (EC) of 1,509 g H 2 Sm 3 h 1 . Average EC obtained with inlet biogas flow rates of 0.024, 0.036 and 0.048 m 3 h 1 was 718,1,013 and 438 g H 2 Sm 3 h 1 , respectively. SO 4 2 and S 0 were the major metabolites produced from biological conversion of H 2 S. Additionally to the satisfactory biodesulfurization capacity, an average increase in methane concentration of y 3.8 ± 1.68 g m 3 was measured in the filtered gas stream throughout 200 days of BTF operation. RT-PCR analyses of archaea communities in the biofilm confirmed dominance of hydrogenotrophic methanogens thus corroborating with the observed strong correlation between CO 2 removal and CH 4 production. Among the three major archaea orders investigated (i.e., Methanosarcinales, Methanobacteriales, and Methanomicrobiales), Methanobacteriales were encountered at highest concentrations (1.9  10 11 gene copies mL 1 ). The proposed BTF was robust efficiently removing H 2 S from biogas stream while concomitantly enhancing the concentration of valuable methane as source of renewable fuel. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Agricultural wastewaters, in particular effluents from swine production, have high concentrations of biodegradable organic matter and ammonium nitrogen. Anaerobic digestion is conven- tionally utilized in these scenarios as primary wastewater treat- ment choice to reduce carbon loads (Anceno et al., 2009) while simultaneously producing biomethane as a source of renewable fuel. The produced biogas is tipically composed of 55e75% methane (CH 4 ), 20e35% carbon dioxide (CO 2 ) and 3,000e5,000 ppmv hydrogen sulfide (H 2 S) (Kao et al., 2012) as well as a variety of other trace contaminants such as silicon, halogens, volatile organic compounds, silanes and siloxanes (De Arespacochaga et al., 2014). Among the undesireable compounds present in the biogas, H 2 S deserves special attention due to its odor, toxicity and highly cor- rosive characteristics (Díaz et al., 2015). Removal of H 2 S from biogas stream is thus required in order to prevent costly damages to overall power plant infrastructure. Different approaches are avail- able to remove H 2 S from biogas stream including physicochemical i.e., chemical absorption, adsorption, cryogenic separation, dry oxidation (Kao et al., 2012) and biological i.e. biofiltration processes (Chung et al., 2010). Among these, biofiltration are considered more environmental friendly and cost-effective than physicochemical processes (Arellano et al., 2009). Biological H 2 S removal efficiency >98% has been reported in lab scale experiments using specific bacteria strains capable of H 2 S oxidation. Numerous cultivable bacteria isolates are known to oxidize H 2 S compounds including Thiobacillus, Thiomicrospira, Thiosphaera, Sulfolobus, Thiomonas * Corresponding author. BR 153 Km 110 P.O. Box 321, 89000-700, Conc ordia, SC, Brazil. E-mail addresses: mateus.pirolli@posgrad.ufsc.br (M. Pirolli), marcio.busi@ embrapa.br (M.L.B. da Silva), melissa.mezzari@unoesc.edu.br (M.P. Mezzari), willian.michelom@posgrad.ufsc.br (W. Michelon), jean.prandini@posgrad.ufsc.br (J.M. Prandini), soares@enq.ufsc.br (H. Moreira Soares). Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman http://dx.doi.org/10.1016/j.jenvman.2016.04.013 0301-4797/© 2016 Elsevier Ltd. All rights reserved. Journal of Environmental Management 177 (2016) 161e168