Synergistic Tannic Acid-Fluoride Inhibition of Ammonia Emissions and Simultaneous Reduction of Methane and Odor Emissions from Livestock Waste

Abstract

Gaseous emissions from livestock production are complex mixtures including ammonia, methane, volatile organic compounds (VOC) and H 2 S. These contribute to eutrophication, reduced air quality, global warming and odor nuisance. It is imperative that these gases are mitigated in an environmentally sustainable manner. We present the discovery of a microbial inhibitor combo consisting of tannic acid and sodium fluoride (TA-NaF), which exhibits clear synergistic inhibition of ammonia production in pure bacteria culture and in pig manure while simultaneously inhibiting methane and odorant (H 2 S and VOC) emissions. In laboratory headspace experiments on pig manure, we used proton-transfer-reaction mass spectrometry and cavity ring-down spectroscopy to measure the effect of TA-NaF on gaseous emissions. Ammonia emission was reduced by more than 95%, methane by up to ~99% and odor activity value by more than 50%. Microbial community analysis and gas emission data suggest that TA-NaF acts as an efficient generic microbial inhibitor, and we hypothesize that the synergistic inhibitory effect on ammonia production is related to tannic acid causing cell membrane leakage allowing fluoride ions easy access to urease.

Effects of combined tannic acid/fluoride on sulfur transformations and methanogenic pathways in swine manure

“…Cumulative methane emission was slightly lower in TA-NaF treated manure than in untreated manure, but the reduction was not statistically significant. This is in agreement with Dalby et al [ 17 ], where no difference was found in methane production during the first 14 days of incubation with 2.5:1 mM TA:NaF. Carbon dioxide production in TA-NaF treated swine manure was not significantly different from untreated swine manure either ( Fig 3B ).…”

“…The detrimental effects of methane, reduced sulfur compounds and several other livestock gases on the climate and environment have raised the demand for innovating sustainable mitigation technologies. In recent studies, methane and reduced sulfur compounds emissions were significantly reduced from swine manure using tannic acid with sodium fluoride (TA-NaF) as inhibiting agent [ 17 ]. It was shown that inhibition with TA-NaF was of synergistic nature and it was proposed that the mode of inhibition was related to TA disrupting the cell membrane, which allows toxic fluoride to flow into the cell and inhibit metabolism [ 17 ].…”

“…In recent studies, methane and reduced sulfur compounds emissions were significantly reduced from swine manure using tannic acid with sodium fluoride (TA-NaF) as inhibiting agent [ 17 ]. It was shown that inhibition with TA-NaF was of synergistic nature and it was proposed that the mode of inhibition was related to TA disrupting the cell membrane, which allows toxic fluoride to flow into the cell and inhibit metabolism [ 17 ]. Dalby et al [ 18 ] studied isotope signatures of methane and carbon dioxide and suggested that acetoclastic methanogens were more susceptible to TA-NaF inhibition.…”

“…Based on a recent study [ 17 ] and earlier observations by Ottosen et al [ 22 ], the hypothesis was that TA-NaF would strongly inhibit methionine degradation, whereas acidification would inhibit sulfate reduction to a higher degree. We expected that both TA-NaF would primarily inhibit acetoclastic methanogenesis, leading to the dominance of hydrogenotrophic methanogenesis [ 18 ].…”

Development of a Real-Time Controlled Bio-Liquor Circulation System for Swine Farms: A Lab-Scale Study

“…In the available literature regarding NH3 as an odor indicator, some mixed results were found. Some studies indicated NH3 as a poor indicator of odor emission [19][20][21][22], whereas contemporary studies reported the inhibition of NH3 emission with simultaneous odor reduction [23][24][25]. In general, NH3 concentration in swine barn is proportional to the amount of protein and amino acids decomposed, and so is the odor emission [26,27].…”