The relatively low aqueous solubility of reduced sulfur compounds limits odor removal in chemical and biological filters for emissions from livestock facilities due to low filter bed residence times. This can be overcome by the addition of an oxidizing agent to enhance mass transfer to the liquid phase. In the present study, the addition of cupric ions to a full-scale alkaline scrubber for eliminating odorant emissions from a finisher pig facility was tested. To minimize precipitation, cupric ions were added in a complex with EDTA with the purpose of enabling catalytic oxidation of sulfur compounds. The experiments were carried out over a 10-week period and odorant concentrations were measured continuously with PTR-TOF-MS (Proton-Transfer-Reaction Time-Of-Flight Mass Spectrometry). During the period, pH was gradually increased from approximately 7.5-9.6. Removal efficiencies of H2S and methanethiol were found to increase significantly at pH > 8.5, mostly pronounced for methanethiol. The modified scrubber was able to reduce H2S and methanethiol emissions by > 99 % and > 80 %, respectively, at pH > 8.5. This was achieved at an empty-bed residence time of only 1.6 s. The total odor emission determined as SOAV (sum of odor activity values) under these conditions was shown to be reduced by

Gaseous emissions from livestock production are complex mixtures including ammonia, methane, volatile organic compounds (VOC), and H2S. 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 (H2S 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.

Robust estimates of gas emissions from full-scale slurry storage tanks are critically needed but remain challenging under farm-scale conditions. Tent-covered slurry tanks are naturally ventilated systems in which air exchange varies over time. The tracer decay method offers a practical approach to quantify air exchange rates and, when combined with concentration measurements, enables emission estimation. This study evaluated tracer gas selection and concentration, assessed horizontal mixing within the headspace, and compared different fitting approaches for tracer decay under full-scale conditions. Pure nitrous oxide and diluted butene were tested as tracers following pulse injection into a tent-covered digestate tank. Decay curves were analyzed using constant and time-varying approaches to estimate air exchange. The choice of fitting method had little influence on average methane emission estimates but substantially affected short-term emission dynamics. Under variable ventilation conditions, time-varying approaches were required to represent temporal changes in air exchange. The Kalman-based approach provided a stable reconstruction of ventilation dynamics without introducing excessive noise. Tracer concentrations at two sampling positions located approximately 30 m apart were consistent after an initial homogenization period, indicating effective horizontal mixing at the measurement height. However, butene concentrations approached background levels during decay, resulting in unstable air exchange estimates, whereas nitrous oxide remained clearly distinguishable from background throughout the monitoring period. Estimated air exchange rates ranged from approximately 90 to 300 m3 h-1 for a tent-covered tank containing 4500 m3 slurry. The tracer decay method provided robust average methane emission estimates when tracer concentration, monitoring duration, and mixing conditions were adequate.

Field application of animal slurry contributes to emissions of ammonia (NH3), non-methane volatile organic compounds (NMVOC), and hydrogen sulphide (H2S), which are harmful to the environment, and cause odour nuisance. Slurry acidification with sulphuric acid is a proven solution to minimize NH3 losses; however, lowering the slurry pH could enhance the volatilization of acidic compounds such as volatile fatty acids and H2S. While several reliable techniques exist to measure NH3 emissions, research on NMVOC and H2S volatilization from slurry field application is still scarce, and the previous work has relied solely on enclosure measurement methods. This work aimed to measure NH3, NMVOC and H2S emissions after trailing hose application of untreated pig slurry to permanent grassland using an enclosure (dynamic flux chambers; DFC) and a micrometeorological (backward Lagrangian Stochastic; bLS) method. Moreover, the effect of increasing sulphuric acid dosages on NH3 and odour emissions was investigated from small replicated plots using DFC. Acidification did not affect NH3 emissions, while it significantly enhanced volatile fatty acids losses. The low dry matter content of the slurry may have facilitated infiltration into the soil, resulting in low NH3 fluxes, thereby obscuring the acidification effect on cumulative NH3 emissions. The DFC and bLS methods yielded similar NH3 and NMVOC cumulative emissions after untreated slurry application, likely due to comparable air exchange conditions inside the DFC and in the atmospheric boundary layer.

Field application of biochar can be challenging due to loss through dust release and uneven spreading, and incorporation of biochar into organic fertilisers has been proposed as a practical application strategy. If biochar is added to the solid fraction prior to field application, it must be incorporated before or during storage, making its effect on storage emissions important to investigate.This study investigated how biochar addition to the solid fraction from separated digestate affected emissions during storage. Emissions from two full-scale stockpiles were determined over 85 days using the backward Lagrangian stochastic dispersion model combined with up- and downwind concentration measurements. One stockpile was amended with 10% (w/w) biochar, while the other was unamended. The CH4 emissions were consistently lower from the biochar-amended stockpile during both covered and uncovered periods. Higher oxygen concentrations across depths and elevated core temperatures in the biochar-amended stockpile indicate improved aeration and enhanced aerobic degradation. Emissions of N2O and NH3 were below measurable levels in both treatments. To the best of current knowledge, this is the first field-scale study to quantify the effect of biochar amendment on gas emissions from stockpiled solid fractions of anaerobically digested slurry. The results provide field-scale evidence that biochar enhances gas diffusion and shifts decomposition towards aerobic pathways, suppressing methanogenesis without increasing NH3 or N2O emissions. These findings advance the state of the art beyond small-scale and composting studies by demonstrating that the effect of biochar on CH4 emissions is detectable and consistent at full scale under practical field conditions.

Livestock manure is a major source of methane emissions. Direct emission measurement is time-consuming and expensive while mathematical models offer a cost-effective alternative to achieve emission estimates for specific source categories. However, their accuracy must be validated by measurements. In this study, the performance of an Arrhenius-type model and the Anaerobic Biodegradation Model (ABM) was investigated at a Danish growing-finishing pig farm over three batches. Continuous methane measurements were conducted using cavity ring-down spectroscopy, and slurry samples were collected to determine the specific methane production rate. Slurry temperature and chemical composition of slurry, faeces, urine, and feed were used as model inputs. In a fourth batch, slurry samples were collected before and after flushing to assess methanogen identity, abundance, and activity. The methane production rate from slurry samples was markedly lower than the in situ measured methane emissions. The ABM and Arrhenius model underestimated the emissions by 19 and 40%, respectively, although dynamics were captured relatively well and the estimation was improved after optimisation. The microbial analysis revealed that Methanosphaera was the most abundant methanogenic genus but exhibited only marginal activity. Methanoculleus was the most active genus, except in the late stage of the batch where Methanosarcina dominated, contributing over 90% of the methanogenic activity. While ABM shows promise for achieving farm-specific emission estimates, more studies at laboratory-scale are needed to optimise key parameters, and additional farm-specific data should preferably be identified in order to represent real-world variations in methane emissions.

Greenhouse gas emission from liquid livestock manure storage is a considerable contributor to global warming and accurate farm-scale models for predicting emission are needed for estimating effects of manure management strategies. In this study we measured degradation of organic matter components of pig slurry with anaerobic and aerobic manure surface and at 10℃ and 20℃. Simultaneously, methane and carbon dioxide emission were measured and carbon emission from both anaerobic and aerobic processes was determined. Carbon dioxide loss due to surface respiration, did not limit methane emission during the incubation experiment at 10℃ and 20℃, but limited production of methane during subsequent anaerobic digestion at 38℃. Surface respiration rates varied between 10 - 80 g CO2 m-2 day-1 and temperature dependent rate equations describing surface respiration was implemented in a farm-scale methane emission model (ABM). ABM simulations suggested that ca. 10% of carbon loss from typical slaughter pig barns and < 2% from outdoor pig manure storage was as carbon dioxide from surface respiration. Simulations also indicated that slurry filling level and seasonal variation in temperature considerably influenced methane to carbon dioxide emission ratio. This combined experimental and modelling study suggest that farm-scale models must reflect carbon loss from both aerobic and anaerobic process to accurately capture carbon emission dynamics and the farm-scale greenhouse gas emission.

Gaseous emissions from slurry storage tanks represent significant environmental and climate challenges. Accurate measurements of these emissions are essential for understanding their impact and developing effective mitigation strategies. However, measuring emissions of methane, ammonia, and nitrous oxide from full-scale slurry storage tanks can be challenging and it is practically impossible to obtain replicate measurement of the same slurry or test treatments under identical conditions.To overcome this challenge, Computational Fluid Dynamics (CFD) modeling was used to investigate suitable dimensions for small-scale tanks. A tank diameter of 2.4 m and a height of 1 m was found suitable for emission measurements. As a method for measuring the emissions the Micrometeorological Mass Balance (MMB) method, where concentration and wind speed is measured at multiple heights above the tank, is a promising candidate as it has been proven to work on full-scale tanks for methane (Kariyapperuma et al., 2018; Park et al., 2010).The plan was to validate the use of MMB on the small-scale tank while measuring in parallel with the backward Lagrangian Stochastic (bLS) method that have previously been used on full-scale slurry tanks (Lemes et al., 2022). Concurrent measurements with MMB and bLS were not useful as the concentration differences used for bLS were too small to estimate emissions. The measurement on pig slurry showed MMB emissions for methane and ammonia comparable to baseline emission in a recent review (Kupper et al., 2021), but the concentration response for ammonia indicated that it is questionable using a closed path instrument to measure ammonia emissions with MMB. In another validation experiment with IDM and MMB a known quantity of gas was released from a grid with 24 critical orifices inside the small-scale tank. In this case, bLS had a good recovery whereas MMB did not. The discrepancy was likely caused by the gas being released from discrete points and not uniformly from the entire surface. In a third validation experiment, MMB was compared to the Tracer Gas Method (TGM), where a known quantity of gas was released at three positions just below the slurry surface. The TGM and MMB emissions from methane agreed well in some intervals, but differed greatly in others, highlighting the challenges of measuring emissions from a small tank.The observed issues emphasize the complexity of validating emissions from small-scale slurry tanks. Downscaling the tank also downscales emissions, which can be an issue using some methods and thereby making it difficult to do cross validation with different methods in parallel.Downscaling provides opportunities to investigate natural variations and emissions of different slurry types under the same weather conditions in replicates, but the choice of an appropriate micrometeorological method is a complex challenge. References:Kariyapperuma et al.: Agric. For. Meteorol., 258, 56–65, doi:10.1016/j.agrformet.2017.12.185, 2018.Kupper et al.: Biosyst. Eng., 204, 36–49, doi:10.1016/j.biosystemseng.2021.01.001, 2021.Lemes et al.: ACS Agric. Sci. Technol., 2(6), 1196–1205, doi:10.1021/acsagscitech.2c00172, 2022.Park et al.: Agric. For. Meteorol., 150(2), 175–181, doi:10.1016/j.agrformet.2009.09.013, 2010.

The effect of slurry separation on CH4 and N2O emissions was investigated in two pilot-scale storage experiments during summer (123 days) and winter (159 days). Pig slurry, anaerobically digested slurry and their corresponding liquid fractions after separation were stored in triplicate. The Anaerobic Biodegradation Model was used to interpret the results of pig slurry. The separated liquid fractions had a higher conversion of initial volatile solids content and different explanations are discussed. There was no clear difference in annual emission between separated and unseparated slurry, although variability was high. The conditions in the field experiment were used for the modelled emissions, and the results demonstrated that the initial microbial community, pH, volatile solids content, and slurry temperature can change the results dramatically. These factors should always be reported, to be able to compare literature values and for future modelling work.

Manure storage contributes significantly to agricultural methane (CH4) emissions. Surface crusts forming during liquid manure (slurry) storage can act as microbial filters that oxidize CH4. However, in open storage tanks, the variable environment limits growth and activity of methanotrophs. This study investigated a novel automated ventilation control (auto-control) to enhance CH4 oxidation during storage of cattle slurry with a well-developed crust. Implemented in pilot-scale storage tanks with slurry and crusts transplanted from a practical farm, the auto-control regulates CH4 and O2 concentrations above the crust to enhance CH4 oxidation. Concentration profiles of CH4, carbon dioxide (CO2) and nitrous oxide (N2O) indicated that O2 penetrated 30-50 mm into the crust. Methane oxidation efficiency was first quantified at fixed ventilation rates, and subsequently using the auto-control ventilation. Isotopic analysis of CH4 emissions in early summer confirmed a CH4 oxidation efficiency (fox) of 20-50 % at fixed ventilation rates of 0.5-70 m3 h-1. In late summer, fox had increased to 75-80 %, and operation under auto-control reduced ventilation rates and CH4 emissions compared to a fixed ventilation rate simulating open storage. This was confirmed in additional campaigns during September and October. Microbial analyses confirmed a high abundance and diversity of methanotrophs in the upper 5 cm of the crust. These findings underscore the potential to optimize manure storage conditions for enhanced microbial CH4 oxidation and reduced emissions.

There is significant interest in mitigating the environmental impacts of cow and pig production, and biogas manufacture. Ammonia emissions pollute groundwater, public agencies regulate odor for obvious reasons, and there is an increased focus on decreasing methane emissions including public pledges by countries and food companies. Many potential solutions are available, with varying cost, complexity, size, and removal efficiency constraints. Here we present the results of a field trial of an innovative new technology, the Methane Eradication Photochemical System (MEPS). Results included demonstrating reduction in ammonia emissions from a pig barn of 94 % of 3 ppm, reduction in the odorous compound hydrogen sulfide from a pig barn of 80 % at 1.5 ppm, and removal of methane from a cow barn of 51 % at 80 ppm. For conditions in a cow barn, the volumetric power input was 171.3 kJ/m3, corresponding to a specific energy input of 0.5 kWh/gCH4. When scaled this result shows that MEPS at its current level of optimization has the potential to destroy methane at a cost of $500/tCO2e, using methane’s 20 year GWP of 80, with the co-benefit of significantly reducing the emission of ammonia and odor.

Pig farming is a major contributor to the emissions of greenhouse gases and pollutants. Methane (CH4), with a global warming potential 27 times that of carbon dioxide (CO2), accounts for up to 80% of the greenhouse gases at the farm level. Concurrently, pig production is responsible for 15% of the global livestock-related ammonia (NH3) emissions. Mitigation strategies that are highly effective and environmentally friendly are lacking. Here, we present a novel slurry treatment driven by the biological conversion of glycerol by Limosilactobacillus reuteri with the support of indigenous slurry microbiota activity, leading to the formation of the reuterin system, a broad-spectrum antimicrobial. The in situ production of reuterin reduced CH4 emissions by up to 95% in pig slurries and lowered CO2 and NH3 emissions, depending on the slurry type. Taken together, the microbial conversion of glycerol by L. reuteri holds promise as a biological slurry treatment to mitigate agriculture-related greenhouse and pollutant gas formation.

There is significant climate and environmental benefit to mitigating the environmental impacts of livestock and biogas production. Methane is a strong greenhouse gas that leads to global warming, ammonia emissions pollute groundwater, and odor is a serious local problem which is often regulated. There is a growing focus on the reduction of global methane emissions, including public pledges by countries and food companies. Although some solutions exist for ammonia and odor removal, no scalable method effectively treats methane from enteric fermentation or integrates the mitigation of all three pollutants. It was found that MEPS, utilizing UV-light, chlorine gas and a NaOH scrubber, could remove 98 %, 94 %, and 80 % of methane, ammonia, and hydrogen sulfide (respectively) from the air in a pig barn. Tests in a dairy barn found a quantum yield of 1.54 %, corresponding to a specific energy input of 0.5 kWh/g{CH4}, when operating at a methane removal efficiency of 51 %. While there is much room for optimization of the MEPS process, this work demonstrates an important step in developing scalable technology for eradicating low concentration methane sources from agriculture.

BACKGROUND:Breastfeeding is a major determinant of gut microbiota composition and fermentation activity during the first months of life. Breastmilk delivers human milk oligosaccharides (HMO) as substrates for microbial intestinal fermentation. One of the main metabolites that accumulates in feces of breastfed infants is 1,2-propanediol (1,2PD) resulting from the metabolism of fucosylated HMO. 1,2PD is used in microbial cross-feeding to produce propionate, but 1,2PD is also an alcohol that can impact the state of the microbial cell envelope. To shed further light on an understudied compound in the infant gut, we investigated the genetic and metabolic potential of the early gut colonizer Clostridium perfringens to utilise 1,2PD, and the interactions of 1,2PD with the cell envelope. RESULTS:Based on genome analysis, C. perfringens FMT 1006 isolated from infant feces possessed most genes of the pdu operon related to 1,2PD metabolism. C. perfringens consumed 1,2PD (78%) and produced 1-propanol as the main metabolite, while propionate was not detected. In agreement, genes responsible for 1,2PD utilisation and propanol formation (pduCDE, dhaT) were highly expressed. When cultivated in the presence of 1,2PD and glucose, a higher proportion of 1,2PD carbon (87%) was recovered as compared to incubation with only 1,2PD (34%). At the same time, lactate and acetate were formed in a ratio of 2.16:1.0 with 1,2PD and glucose compared to a ratio 9.0:1.0 during growth with only glucose possibly due to reallocation of the NAD+/NADH pool in favor of 1-propanol formation. The presence of 1,2PD slightly increased membrane fluidity and modified the composition of the membrane to a higher content of elongated glycerophosphoethanolamines. CONCLUSION:We provide here new knowledge on the metabolism of 1,2PD by a microbial species that is present during breastfeeding and observed that C. perfringens metabolised 1,2PD mainly to propanol. The presence of 1,2PD had little impact on membrane fluidity and let to modifications of membrane lipid composition. Collectively, these findings advance our understanding of on intestinal metabolite-microbe interactions during breastfeeding.

Agriculture is a major source of ammonia, methane, and odorants. Slurry management contributes significantly to their emissions and understanding the release mechanism of these gaseous compounds is essential for developing effective mitigation strategies. To identify key factors governing ammonia, methane, and slurry odorant emissions under controlled conditions, we developed an experimental chamber with partially slatted floor. The study includes simultaneous increases in slurry surface area and volume, increases in volume alone, setting different ventilation rates, and the effects of fouling. Ammonia emissions were significantly influenced by the simultaneous increase in both surface area and volume, by the ventilation rate and by the application of fouling. Methane emissions were significantly affected by the simultaneous increase in both surface area and volume, as well as the increase in volume alone, while ventilation rate or fouling had no significant effect on emissions. The dominant odorants emerging from slurry in terms of odour activity value were 3-methyl-1Hindole, 4-methylphenol, and hydrogen sulphide. Hydrogen sulphide exhibited emission patterns similar to methane, while emission patterns of 4-methylphenol and 3-methyl-1H-indole were more comparable with those of ammonia. Our results indicate that mitigation strategies should focus on controlling the slurry surface area and preventing fouling to reduce ammonia and odour emissions whereas maintaining a low slurry volume limits methane and hydrogen sulphide emissions.

Livestock slurry is an important anthropogenic source of ammonia, methane, and odour. Novel techniques need to replace standard practices to mitigate emissions. This study explores a slurry system based on funnels with frequent slurry discharge and partial pit ventilation in an experimental pig house with farrowing pens for loose sows. In the control section, a flat bottom slurry system was installed and emptied only at the end of the batch. Ammonia and methane concentrations were quantified with cavity ring-down spectroscopy and odorants with proton-transfer-reaction mass spectrometry. Applying 30 % pit ventilation in both sections reduced ammonia emissions by approximately 50 % in the funnel section compared to the control. Without pit ventilation in the control, the ammonia emissions were 25 % lower in the funnel section with 30 % pit ventilation. Methane was 20-80 % lower in the funnel section and the odour activity value was reduced by more than 50 % in all batches compared to the control. Alternative pit ventilation percentages of 20 and 40 % revealed that the pit ventilation should not be higher than 30 % to avoid increased emissions The funnel system with frequent slurry discharge significantly reduces ammonia, methane, and odorants emissions relative to the control system. Furthermore, the inclusion of partial pit ventilation reduces NH3 concentration above the slats providing a healthier environment for the sow and piglets.

Different technologies can be utilised to mitigate environmentally harmful ammonia (NH3) emissions after field application of liquid animal manure (slurry). After a solid-liquid separation, air-plasma technology can acidify the liquid fraction and enrich its nutrient value by increasing the amount of inorganic nitrogen. The present work investigates the emissions of NH3 and volatile organic compounds (VOC) after field application of the following fractions of pig slurry and slurry digestate: i) untreated slurry (UN), ii) liquid fraction of slurry (LF), iii) liquid fraction of slurry treated with air from the plasma treatment (LP). Emissions were measured with a system of wind tunnels and a cavity ring-down spectrometer for NH3 concentration measurements and a proton-transferreaction mass-spectrometer for measurements of VOC. For both slurry types, the cumulative NH3 emissions were in the following order UN > LF > LP. All the differences were significant (P < 0.05), except between pig slurry LF and LP. The reduction in cumulative NH3 emission obtained by the treatments compared to UN were 55-74% and 70-89% for LF and LP, respectively. The slurry separation decreased dry matter by 46-54% and resulted in a rapid decrease in slurry exposed surface area after application, presumably due to high infiltration. Several VOCs were measured after application of the slurry, but continuous emission was undetectable for all VOCs. The very low VOC emission was presumably due to high infiltration of the low dry matter slurry treatments and low concentration of VOC in the digestate.

Emissions from agriculture are a worldwide problem as it is the major anthropogenic source of ammonia, methane, and nitrous oxide. Several efforts have been made to mitigate emissions. To achieve this, reliable measuring techniques are necessary to quantify the impact of the emissions. Different techniques relying on different principles are available. Generally, these techniques demonstrate good agreement on their measurements but there is a lack of studies that thoroughly investigate cross-interferences. In this work, three different models of Cavity Ring-Down Spectrometers measuring ammonia, nitrous oxide, and methane were tested in parallel for potential biases due to interference from ammonia, water vapor, and twelve volatile organic compounds commonly present in agricultural environments. Our results showed a small negative bias with increasing humidity on nitrous oxide and minor interferences of ammonia on nitrous oxide and methane. None of the tested volatile organic compounds interfered with ammonia, methane, or nitrous oxide measurements. Overall, concentration measurements of ammonia, nitrous oxide, and methane with cavity ring-down spectrometry have proven reliable under typical agricultural conditions. Minor interferences were only observed under exceptional conditions.

Odor nuisance is a major impediment for public acceptance and wider implementation of biogas plants. Knowledge on composition and dynamics of emissions from these plants is highly needed for development of robust mitigation solutions. In this study, odorant emissions were investigated from two biogas plants of different sizes and capacities. Measurements using proton-transfer-reaction mass spectrometer (PTR-MS) revealed that hydrogen sulfide was the main odorant and constituted 82% and 71% of the odor activity sums (SOAV) at the two studied plants, respectively. Long-term time-resolved measurements furthermore revealed that emissions were highly dynamic with distinct short-term emission peaks. By deploying an array of electrochemical sensors, the main sources of hydrogen sulfide emission were subsequently identified and correlated with operational data to identify the major causes for the highly fluctuating emissions. Addition of biomasses in the form of animal slurry to pre-tanks, were shown to be the major cause of periodic hydrogen sulfide emission within the range of 50-1200 ppm. Such hydrogen sulfide peak emissions could challenge odor abatement from biogas plants and should be taken into account when designing odor abatement technologies for biogas plants.

Mitigation of methane (CH4) emissions from slurry pits within pig barns can be achieved through treatment of residual slurry left after frequent flushing of the slurry pits. In this study, dosages of additives such as sodium dodecyl sulfate (SDS) and hydrogen peroxide (H2O2) were optimized to achieve reduction in CH4 emissions from residual pig slurry during storage. In addition, the effects on emissions when both the treatments were combined and the effects of SDS treatment on slurry acidified with sulfuric acid (H2SO4) were studied in order to reduce CH4 and ammonia (NH3) emissions from residual pig slurry storage. A maximum of 98% and 70% reduction in CH4 emissions were achieved with SDS and H2O2 treatments, respectively. The combination of SDS and H2O2 did not increase efficiency in reducing CH4 emissions compared to SDS treatment alone. Whereas the application of SDS to slurry acidified with H2SO4 (pH 6.2) increased the CH4 mitigation efficiency by 15-30% compared to treating slurry with only SDS. The combined treatment (SDS + H2SO4) reduced NH3 emissions by 20% compared to treating slurry with H2SO4 (pH 6.2) alone. Hereby, combined treatment (SDS + H2SO4) can reduce both CH4 and NH3 emissions, with a reduced amount of chemicals required for the treatment. Hence, application of SDS at concentrations <2 g kg(-1) to acidified slurry is recommended to treat residual pig manure in pig barns.