A study of a pilot-scale biogas bio-filter system for utilization on pig farms

• Published in: The Journal of agricultural science 2014-04, Vol.152 (2), p.217-224
• Main Authors: SU, J.-J., CHEN, Y.-J., CHANG, Y.-C.
• Format: Article
• Language: English
• Subjects: Agricultural biotechnology; Agronomy. Soil science and plant productions; Animal productions; Biofiltration; Biofuel production; Biogas; Biological and medical sciences; Biotechnology; Climate Change and Agriculture Research Papers; Commercial farms; Energy; Ferns; Flow rates; Fundamental and applied biological sciences. Psychology; Hogs; Hydrogen sulfide; Industrial applications and implications. Economical aspects; Livestock industry; Roots; Sulfur dioxide; Sulfur oxides; Swine; Terrestrial animal productions; Vertebrates; Wastewater treatment
• ISSN: 0021-8596; 1469-5146
• DOI: 10.1017/S0021859612001086

Combustion of biogas containing hydrogen sulphide (H2S) yields highly corrosive sulphur oxides, thereby limiting the use of biogas for heat and power generation. The current study developed and tested a pilot-scale biogas bio-filter system (BBS) to replace conventional water scrubbing systems at a commercial pig farm in Miaoli County, Taiwan. A 62·8-litre pilot-scale BBS, packed with dried aerial roots from the common tree fern (Sphaeropteris lepifera) and a mixture of dried aerial roots and plastic rings as bio-carriers and inoculated with sulphur oxidizing bacteria, was installed at a commercial pig farm. H2S concentration was 5600 mg/m3 and the biogas flow rate was 4 litres/min. The pilot-scale BBS could remove 26·9 g H2S/m3/h using a bio-filter that operated at a 7% (v/v) O2 level continuously for >200 days. It was found that most H2S was oxidized to elemental sulphur (S0) and accumulated on the surface of the dried aerial roots (0·084 g S0/g aerial root) in the BBS. The dried aerial roots and plastic Raschig ring mixture was more efficent at sulphur dioxide removal than the dried aerial roots on their own. The pH and sulphate (SO42−) concentrations of water dropping from the BBS were 1·6 ± 1·0 and 28 680 ± 8253 mg/l, respectively. However, sulphur is the dominant product of sulphur oxidizers at the 7% O2 level. Periodical flushing of the bio-filter with the effluent from the wastewater treatment system on the farm can maintain high efficiency of H2S removal.