Applied Engineering in Agriculture Vol. 33(3): 407-418 © 2017 American Society of Agricultural and Biological Engineers ISSN 0883-8542 https://doi.org/10.13031/aea.12145 407 DRY SCRUBBING OF HYDROGEN SULFIDE GAS USING NANO ZINC OXIDE COATED GLASS BEADS M. S. Borhan, S. Rahman, N. C. Sarker ABSTRACT. Hydrogen sulfide (H 2 S) is one of the most toxic and smelly gases emitted from animal production facilities, which also acts as a catalyst poison in many industrial processes. The principal objective of this research was to develop a dry scrubber to adsorb H 2 S gas efficiently from airstreams mimicking air exhausts of animal and poultry barns at the ambient atmospheric condition. Nano zinc oxide (nZnO) coated 3-mm sized glass beads were investigated to adsorb H 2 S gas in a vertical dry scrubber setting. Colloids of nZnO were prepared and thin films of nZnO were grown on the surfaces of commercially available glass beads following a sol-gel method. The sizes of nZnO on glass bead surfaces ranged from nm to µm and found to be clustered due to the repeated coatings on the same surfaces. The energy dispersion spectroscopy (EDS) analysis confirms the presence of sulfur (S) compound that indicated a conversion of H 2 S into zinc sulfide (ZnS) on nZnO coated bead surfaces. The highest H 2 S breakthrough capacity of 2.54 mg H 2 S g -1 sorbent was observed. Heating the beads at 550°C regenerated glass beads effectively but experienced a gradual loss of reactivity as a number of regeneration cycles progressed. This research demonstrated that nZnO supported on glass beads are promising adsorbents for capturing H 2 S gas from airstreams at ambient temperature. Keywords. Airstreams, Breakthrough capacity, Hydrogen sulfide, Nano zinc oxide, Regeneration. aseous emissions from animal barns, especially swine housings with in-house deep pits or outside liquid and solid manure storages, and poultry houses release a large portion of greenhouse gas (GHG) that causes the greenhouse effect by absorbing infra- red radiation and hydrogen sulfide. Hydrogen sulfide (H 2 S) is toxic and if present in sufficient quantities, it poses a health hazard. For example, a higher concentration of H 2 S gas in swine production facilities is recognized for frequent incidents of deaths of livestock and humans associated with liquid manure storage pits (Donham et al., 2006). According to Occupational Safety and Health Administration (OSHA) standard, enforceable exposure limit for a worker in general industries are 20 ppm for 8 h, but not more than 50 ppm (peak) for a single time exposure up to 10 minutes (OSHA, 1997). In addition, H 2 S is highly corrosive when reacts with water/water vapor to form a corrosive acid gas that can at- tack metals and plastics. Thus, H 2 S is likely to reduce the life of pipelines and internal parts of an internal combustion en- gine if biogas is not cleaned for H 2 S at the downstream of the combined heat and power generation systems. Hydrogen sulfide (H 2 S) is formed by the process of bac- terial sulfate reduction and decomposition of sulfur-contain- ing organic compounds in manure under anaerobic condition (Thu, 2002). The amount of H 2 S gas emission depends on bacterial populations paired with temperature, pH, and liquid content of manure (Washio et al., 2005; Spellman and Whiting, 2007). Therefore, to ensure sustainable livestock production, maintaining healthy environments for both in- door (emissions in the housing) and outdoor (releasing to the environment) conditions are critical. Existing gaseous miti- gation options related to livestock manure management are mainly focused on feed manipulation, animal management, and processes to treat and manage animal manure. However, limited research has been done for treating gaseous pollu- tants exited from animal buildings to the ambient air. In con- trolled environment livestock production facilities, biofilters and wet scrubbers (acid and trickling filters) are commonly used to treat the air before leaving the barns. The accumula- tion of high ammonia, airborne dust and non-uniform distri- bution of moisture were the major limitations of biofilters operation (Melse and Ogink, 2005). Similarly, widely used wet chemical scrubbers for treating gaseous emission and odor pollutants have shown several limitations, including high operating costs, generation of chlorinated compounds, need to store and dispose of hazardous chemicals on-site, and use of large amounts of water (Wang et al., 2007). In recent years, dry scrubbing technology has appeared as a po- tential alternative that has fewer problems compared to wet scrubbing. Therefore, developing a dry scrubber with regen- erative packing material for convenient operation and effi- cient removal of H 2 S from the exhaust air stream of animal production facilities is lacking. Submitted for review in October 2016 as manuscript number PAFS 12145; approved for publication by the Plant, Animal, & Facility Systems Community of ASABE in March 2017. The authors are Md Saidul Borhan, ASABE Member, Research Specialist, Shafiqur Rahman, ASABE Member, Associate Professor, and Niloy Chandra Sarker, Graduate Student, Ag and Biosystems Engineering, North Dakota State University, Fargo, North Dakota. Corresponding author: Shafiqur Rahman, Department of Ag and Biosystems Engineering, North Dakota State University, PO Box 6050 Fargo, ND, 58108-6050; phone: 701-231-8351; e-mail: s.rahman@ndsu.edu. G