Department of Mechanical Engineering of Agricultural machinery, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
Department of Environmental Engineering, Technical University of Denmark, DK-2800, Kgs Lyngby, Denmark.
Department of Chemical Engineering and Environmental Technology, Escuela de Ingenierías Industriales, Sede Dr. Mergelina, University of Valladolid, Dr. Mergelina s/n,47011 Valladolid, Spain.
The production of biogas from sulfate-rich materials under anaerobic digestion results in the formation of hydrogen sulfide (H2S). The recommended level of H2S in the produced biogas for direct combustion purposes is in the range of 0.02 to 0.05% w/w (200 to 500 ppm), therefore, desulfurization is required to avoid damages to combustion equipment and prevent the formation of sulfur dioxide (SO2) which is an acid rain precursor. It has been well documented that physical, thermal, and chemical desulfurization approaches suffer from high operation costs as well as waste production needing to be disposed of. Accordingly, a great deal of efforts has been put into biological methods because of being more environmentally friendly and more economically advantageous in comparison with the other techniques. Biotrickling filtration (BTF) and microaerobic desulfurization have shown a high potential for H2S removal at pilot- and large-scale plants. Despite all the progress made and the promising aspects keeping these methods at the core of interest, there are still challenges to be addressed. The present article attempts to briefly review and discuss the challenges and future prospects of BTF and microaerobic desulfurization.
- Prospects and challenges of biotrickling filtration and microaerobic desulfurization are discussed.
- Biotrickling filtration is mainly limited by oxygen availability and mass transfer coefficient.
- Providing dissolved oxygen to biotrickling units and using multi-stage filtration improve removal efficiency.
- Under microaeration conditions, H2S removal mostly occurs at headspace highlighting the importance of optimizing the design of headspaces.
- Microaeration offers lower cost for desulfurization purposes.