Emissions of ammonia, carbon dioxide, and hydrogen sulfide from swine wastewater during and after acidification treatment: Effect of pH, mixing and aeration

摘要

This study aimed at evaluating the effect of swine slurry acidification and acidification-aeration treatments on ammonia (NH_3), carbon dioxide (CO_2) and hydrogen sulfide (H2S) emissions during slurry treatment and subsequent undisturbed storage. The study was conducted in an experimental setup consisting of nine dynamic flux chambers. Three pH levels (pH = 6.0, pH = 5.8 and pH = 5.5), combined with short-term aeration and venting (with an inert gas) treatments were studied. Acidification reduced average NH3 emissions from swine slurry stored after acidification treatment compared to emissions during storage of non-acidified slurry. The reduction were 50%, 62% and 77% when pH was reduce to 6.0, 5.8 and 5.5, respectively. However, it had no significant effect on average CO_2 and H_2S emissions during storage of slurry after acidification. Aeration of the slurry for 30 min had no effect on average NH_3, CO_2 and H_2S emissions both during the process and from stored slurry after venting treatments. During aeration treatment, the NH_3, CO_2 and H_2S release pattern observed was related to the liquid turbulence caused by the gas bubbles rather than to biological oxidation processes in this study.