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 Cl 2 ) 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.

Removal of Odor-Causing Substances by a Pilot-Scale Oxidative-Reductive Scrubbing Tower System

“…These compounds were widely and commonly found in the preceding studies that monitored the ambient air qualities of waste disposal and landfill sites (Allen et al, 1997;Zou et al, 2003). A strong correlation between the concentrations of odor and two sulfur-containing compounds, hydrogen sulfide and mercaptans, was found in our preceding study as well (Chen et al, 2012).…”

“…The early published study has indicated the occurrence of strong pH variations in both scrubbers when this twostage chemical wet scrubbing technology was operated as a batch system in bench-scale (Chen et al, 2012). As shown in Fig.…”

“…Simply speaking, after the removal of excess moisture and large and hard objectives, the composts were ground and mixed with bulking materials (mostly animal wastes) and seed composts (wood chips and leave) (Shin Yu Agri, Inc., Pingtung, Taiwan) at predetermined weight ratios and were stored at 4°C. Different and broad weight ratios of the kitchen waste to bulking materials to seed composts ranging from 86:7:7 to 92:%:3 for the preparation of composting gases has been investigated in the preliminary study with no significant impacts on the properties of the composting gases produced being observed (Chen et al, 2012).…”

“…A detailed description for the preparation method of this composting gas is available in our preceding published study (Chen et al, 2012). Simply speaking, after the removal of excess moisture and large and hard objectives, the composts were ground and mixed with bulking materials (mostly animal wastes) and seed composts (wood chips and leave) (Shin Yu Agri, Inc., Pingtung, Taiwan) at predetermined weight ratios and were stored at 4°C.…”

Quantification of Hydrogen Sulfide and Methanethiol and the Study of Their Scavenging by Biocides of the Isothiazolone Family

“…[3] In the flavour and fragrance industry, H 2 S and CH 3 SH find beneficial applications in the flavouring of foods such as meat or coffee products. [4] These sulfur compounds may contribute to toilet, [5] kitchen [6] or breath [7] malodours, and thus for homecare products, they should be prevented from being formed or should be counteracted with a perfume.…”