Treating Odorous and Nitrogenous Compounds from Waste Composting by Acidic Chlorination Followed by Alkaline Sulfurization

As composting becomes a socially acceptable and environmentally sound strategy for sustainable waste disposal and management, its adversely environmental impacts by fugitive emissions of odor-causing chemicals and volatile organic compounds (VOCs) have caused a great deal of concern. Of many VOCs, several nitrogenous compounds such as ammonia and amines have been known to cause malodor and adverse impacts on the nearby environment and public health. In this study, a novel two-stage wet scrubbing technology, which consisted of acidic chlorination followed by alkaline sulfurization, has been tested for treating odorous and nitrogenous compounds produced by waste composing. Performance of this approach was characterized in terms of the treatment efficiency of ammonia, amines, and more importantly, the variety of gas malodor and the associated intensity after treatment, with respect to the effects of pH and different oxidizing (sulfuric acid and sodium hypochlorite) and reducing agents (sodium hydroxide, sodium bisulfite, sodium sulfite, and sodium thiosulfate). Chlorine and thiosulfate were more effective oxidizing and reducing agents, respectively. This treatment technology is expected to be suitable for treating waste-composting gases or even other types of waste gas streams, which contain chemicals with diverse physicochemical properties and may be difficult to manage with single or traditional treatment technologies.