Behavior of nitrogen and sulfur compounds in the rice husk pellet bioscrubber and its circulation water

• Published in: Journal of environmental management Vol. 306; p. 114435
• Main Authors: Baek, Soyoung, Kim, Kwang Soo, Bae, Jiyeol
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.03.2022
• Subjects: Autotrophic Processes; Bioreactors; Bioscrubber; Circulation water analysis; Denitrification; Deodorization; Nitrates; Nitrification; Nitrogen; Oryza; Rick husk pellet; Sulfur Compounds; Water; Bioscrubber; Circulation water analysis; Deodorization; Rick husk pellet; Nitrification
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2022.114435

In this study, pellet-type biofilter media was developed with rice husk and applied in a wet scrubber system for odor removal. The lab-scale bioscrubber system was operated for 200 days to evaluate odorous gas removal (i.e., NH3, H2S, methyl mercaptan, and dimethyl sulfide), and the removal mechanism of odor gases was studied by analyzing the behavior of nitrogen and sulfur compounds in circulation water of bioscrubber system. The rice husk pellets supplied the organic carbon source and phosphoric acid necessary for microbial growth, allowing the system to continue successfully for 200 days without any maintenance technology. By analyzing the behavior of the nitrogen and sulfur compounds in the circulation water, we confirmed that the odor gas removal resulted from various mechanisms, including adsorption and biodegradation. Ammonia gas was absorbed by the rice husk pellets and accumulated in the circulation water as nitrite under conditions of sufficient alkalinity and above pH 7. Conversely, when the alkalinity and pH decreased, nitrite was rapidly converted to nitrate. However, H2S gas was oxidized to sulfate and continuously accumulated in the circulation water regardless of the pH and alkalinity. In addition, it was confirmed that the decrease in nitrate in the bioscrubber system was due to heterotrophic denitrification by the organic carbon source supply and autotrophic denitrification by sulfur gas. During the operation of the rice husk pellet bioscrubber for 8 months, under low solubility condition, more than 99% of NH3 and H2S were removed and about 85% of methyl mercaptan (MM) and dimethyl sulfide (DMS) were removed. •Rice husk pellet was developed as a microbiology carrier in bioscrubber reactor for odor gas removal.•Removal mechanisms of odor gases (i.e., NH3, H2S, MM, and DMS) were studied by analyzing the circulation water for 200 days.•The removal efficiency was more than 99% for NH3 and H2S, and the microorganisms were affected by the pH and alkalinity conditions of the reactor.