A novel two-stage scrubbing technology for odor control of kitchen waste composting

Abstract

The odors associated with kitchen waste composting for recycle and reuse, which arise as a consequence of the volatilization of compounds contained within such waste and those formed during decomposition, are a key concern with regard to sustainable kitchen waste treatment and disposal. The aim of this study was to investigate the main composition of the odorous gases from kitchen waste composting, and to develop a novel two-stage oxidative-reductive wet scrubbing technology for effective control of these. The results indicate that the odor concentrations of the kitchen waste composting gases are strongly related to the concentrations of sulfur-containing compounds, hydrogen sulfide and mercaptans. In the two-stage scrubbing technology for odor control, sodium hypochlorite and sodium hydroxide or sodium bisulfite were used as the scrubbing liquids in the acidic and alkaline scrubbers, respectively. The pH levels of the acidic and alkaline scrubbers, the types and concentrations of chlorine in the acidic scrubber, and the type of alkaline scrubbing liquid used, were the main factors that affected the efficiency of this technology for odor removal. Sodium bisulfite solution was used in the alkaline scrubber, with a moderate ranges of total and free chlorine concentrations (150-200 mg/L as Cl2) and relatively high pH values (e.g., pH 9.5-10), and this novel technology was successfully used to treat the odors produced by the kitchen waste composting process.