Removal of odorants from animal waste using Fenton’s reaction

摘要

The purpose of this study was to evaluate Fenton’s reaction as a means of mitigating the problem of offensive odors emitted from livestock manures. The hypothesis to be tested was that hydroxyl radicals generated during this reaction would oxidize odorant compounds, breaking them down to nonodorous products. The deodorization effect was assessed using various chromatographic techniques to determine the concentration of selected odor indicators present in swine slurry and reactor headspaces before and after treatment. The indicators included seven volatile fatty acids, three phenols, and two indoles that were positively correlated with malodors from animal manure. The extent of their removal strongly depended on the concentration of Fenton’s reagents (0 to 40 mM FeCl3, and 0 to 800 mM H2O2), the initial pH of swine slurry (2.0 to 6.5), and the total solids content (0.6 to 2.9% TSC). Control samples treated with no FeCl3 or H2O2 did not show significant reduction of odorant concentration at all pH and TSC levels tested. Acceptable removals of total odorants (65 to 90%) were observed between pH 3.5 and 5.5. When swine slurry (0.7% TSC, pH 5.0) was treated for 2 h with 40 mM FeCl3 at 400 mM H2O2, all odorants were removed completely (100%), except for small amounts of propionic acid. Odorant removal from swine slurry was in good agreement with that from the headspace air (90-100% removal for most measured odorants). Pilot-scale treatment produced encouraging results, surpassing the expectations based on the outcome of laboratory experiments.