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Animal slurry storage is an important ammonia (NH 3 ) emission source. Sulfuric acid (H 2 SO 4 )-modified vermiculite coverage is a new promising technology for controlling NH 3 emission from slurry storage. However, the underlying mechanisms in controlling the mitigation effect remain unclear. Here, a series of experiments to determine the effect of H 2 SO 4 on the modified vermiculite properties, floating persistence, and NH 3 mitigation effect was conducted. Results showed that abundant H 2 SO 4 and sulfate remained on the outer surface and in the extended inner pores of the vermiculite with acidifying H + concentrations higher than 5 M. An initial strong instantaneous acidification of surface slurry released rich carbon dioxide bubbles, strengthening cover floating performance. An acidification in the vermiculite cover layer and a good coverage inhibition interacted, being the two leading mechanisms for mitigating NH 3 during initial 40-50 days of storage. The bacterial-amoA gene dominated the conversion of NH 3 to nitrous oxide after 50 days of storage. Vermiculite with 5 M H + modification reduced the NH 3 emissions by 90 % within the first month of slurry storage and achieved a 64 % mitigation efficiency throughout the 84 days period. With the development of the aerial spraying equipment such as agricultural drones, acidifying vermiculite coverage hold promise as an effective method for reducing NH 3 emission while absorbing nutrients from liquid slurry storage tank or lagoon. This design should now be tested under field conditions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Ammonia (NH 3 ) emissions, the majority of which arise from livestock production, are linked to high concentration of PM 2.5 and lower air quality in China. NH 3 mitigation options were well studied at the small-scale (laboratory or pilot), however, they lack of a large-scale test in China. This study fills this crucial gap by evaluating the cost-benefit of pioneering NH 3 mitigation projects carried out for a whole county - Sheyang, Jiangsu province, China. Measures were implemented in 2019 following two distinct strategies, improved manure treatment for industrial livestock farms, and collection and central treatment for traditional livestock farms. Emission reductions of 16% were achieved in a short time. While this is remarkable, it falls short of expectations from small-scale studies. If measures were fully implemented according to purpose and meet expectations from the small scale, higher emission reductions of 42% would be possible. The cost benefit analysis presented in this study demonstrated advantages of central manure treatment over in-farm facilities. With improved implementation of mitigation strategies in industrial livestock farms, traditional livestock farms may play an increasing role in total NH 3 emissions, which means such farms either need to be included in future NH 3 mitigation policies or gradually replaced by industrial livestock farms. The study found an agricultural NH 3 reduction technology route suitable for China's national conditions (such as the "Sheyang Model")., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Animal slurry storage is an important source of NH 3 emission which has raised a high attention regarding its influence on air quality and environment health. There is an urgent need to develop an efficient, green and safe technology for reducing NH 3 emission. This study introduced a novel method of reducing NH 3 emission from dairy slurry storage using H 2 SO 4 modified expanded vermiculite cover (H 2 SO 4 -VM1). Results showed that NH 3 mitigation of 87% was achieved in the treatment of H 2 SO 4 -VM1 during 77 days of slurry storage, which could be mainly caused by conversion of free NH 3 to NH 4 + in acidified slurry surface and vermiculite layer, the cover barrier for gases emissions, NH 4 + adsorption by vermiculite cover, and direct adsorption of free NH 3 in the vermiculite layer. The NH 3 mitigation of H 2 SO 4 -VM1 was comparable to that (90%) of the traditional method of H 2 SO 4 acidification for slurry storage (H 2 SO 4 -AC1). The N 2 O emission, H 2 S emission, and H 2 SO 4 consumption in H 2 SO-VM1 were 28, 93 and 39% lower than those in H 2 SO 4 -AC1, respectively. Economic cost calculated based on material input in H 2 SO-VM1 method was 0.40 USD m -2 slurry. It's suggested that H 2 SO 4 -VM1 can be a possible alternative for reducing NH 3 emissions from animal slurry storage., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Ammonia stripping is a pretreatment method for piggery biogas slurry, and the effectiveness of the method is affected by many factors. Based on the results of single-factor experiments, response surface methodology is adopted to establish a quadratic polynomial mathematical model relating stripping time, pH value and gas flow rate to the average removal rate of ammonia nitrogen to explore the interactions among various influencing factors, obtain optimized combined parameters for ammonia stripping, and carry out experimental verification of the parameters. The results show that when hollow polyhedral packing is adopted under operating conditions including a stripping time of 90 min, pH value of 11, gas flow rate of 28 m 3 /h, gas-liquid ratio of 2000 and temperature of 30 °C, the average removal rate of ammonia nitrogen in biogas slurry can reach approximately 73%. The experimental value is only 4.2% different from the predicted value, which indicates that analysis on the interaction among factors influencing ammonia stripping of biogas slurry and parameter optimization of the regression model are accurate and effective.

Media depth (MD) and moisture content (MC) are two important factors that greatly influence biofilter performance. The purpose of this study was to investigate the combined effect of MC and MD on removing ammonia (NH 3 ), hydrogen sulfide (H 2 S), and nitrous oxide (N 2 O) from swine barns. Biofiltration performance of different MDs and MCs in combination based on a mixed medium of wood chips and compost was monitored. A 3 × 3 factorial design was adopted, which included three levels of the two factors (MC: 45%, 55%, and 67% [wet basis]; MD: 0.17, 0.33, and 0.50 m). Results indicated that high MC and MD could improve NH 3 removal efficiency, but increase outlet N 2 O concentration. When MC was 67%, the average NH 3 removal efficiency of three MDs (0.17, 0.33, and, 0.50 m) ranged from 77.4% to 78.7%; the range of average H 2 S removal efficiency dropped from 68.1-90.0% (1-34 days of the test period) to 36.8-63.7% (35-58 days of the test period); and the average outlet N 2 O concentration increased by 25.5-60.1%. When MC was 55%, the average removal efficiency of NH 3 , H 2 S, and N 2 O for treatment with 0.33 m MD was 72.8 ± 5.9%, 70.9 ± 13.3%, and -18.9 ± 8.1%, respectively; and the average removal efficiency of NH 3 , H 2 S, and N 2 O for treatment with 0.50 m MD was 77.7 ± 4.2%, 65.8 ± 13.7%, and -24.5 ±12.1%, respectively. When MC was 45%, the highest average NH 3 reduction efficiency among three MDs was 60.7% for 0.5 m MD, and the average N 2 O removal efficiency for three MDs ranged from -18.8% to -12.7%. In addition, the pressure drop of 0.33 m MD was significantly lower than that of 0.50 m MD (p < 0.05). To obtain high mitigation of NH 3 and H 2 S and avoid elevated emission of N 2 O and large pressure drop, 0.33 m MD at 55% MC is recommended., Implications: The performances of biofilters with three different media depths (0.17, 0.33, and 0.50 m) and three different media moisture contents (45%, 55%, and 67% [wet basis]) were compared to remove gases from a swine barn. Using wood chips and compost mixture as the biofilters media, the combination of 0.33 m media depth and 55% media moisture content is recommended to obtain good reduction of NH 3 and H 2 S, and to simultaneously prevent elevated emission of N 2 O and large pressure drop across the media.

Gaseous emissions from animal manure are considerable contributor to global ammonia (NH 3 ) and agriculture greenhouse gas (GHG) emissions. Given the demand to promote mitigation of GHGs while fostering sustainable development of the Paris Agreement, an improvement of management systems is urgently needed to help mitigate climate change and to improve atmospheric air quality. This study presents a meta-analysis and an integrated assessment of gaseous emissions and mitigation potentials for NH 3 , methane (CH 4 ), and nitrous oxide (N 2 O) (direct and indirect) losses from four typical swine manure management systems (MMSs). The resultant emission factors and mitigation efficiencies allow GHG and NH 3 emissions to be estimated, as well as mitigation potentials for different stages of swine operation. In particular, changing swine manure management from liquid systems to solid-liquid separation systems, coupled with mitigation measures, could simultaneously reduce GHG emissions by 65% and NH 3 emissions by 78%. The resultant potential reduction in GHG emissions from China's pig production alone is greater than the entire GHG emissions from agricultural sector of France, Australia, or Germany, while the reduction in NH 3 emissions is equivalent to 40% of the total NH 3 emissions from the European Union. Thus, improved swine manure management could have a significant impact on global environment issues.

The effects of free ammonia (FA) and dissolved oxygen (DO) on nitrite accumulation in the treatment of high ammonium wastewater and on the evolution of the microbial community were investigated. Under high DO conditions (3.75 ± 0.49 mg/L), FA as high as 10.61 ± 2.89 mg NH3/L maintained stable nitrite accumulation rate (NAR) of 84 % with NH4 (+)-N load of 2.05 kg N/(m(3) day) at sludge retention time (SRT) of 15-18 days. After 56 days of operation, Proteobacteria and Nitrosomonas were the dominant phylum and genus, respectively; Nitrosomonas increased from 21.14 to 54.57 %. By contrast, under relative low DO and low FA, nitrite-oxidizing bacteria (NOB) were nearly eliminated (NOB/AOB of 0; ammonium-oxidizing bacteria (AOB)), and NAR of 94 % was achieved with lower NH4 (+)-N load of 0.48 kg N/(m(3) day). DO correlated with AOB and NOB abundance, and FA decreased NOB activity and the NOB/AOB ratio. In conclusion, high FA and high DO conditions are optimal for efficient nitrite accumulation.

• A system analysis was conducted to study NH 3 emission from chicken manure management. • NH 3 EF and mitigation efficiency (ME) database was constructed. • In-house stage contributed most to NH 3 emissions from broiler litter MMS. • Outdoor stage contributed most to NH 3 emissions from layer manure belt MMS. Broiler and layer productions are important ammonia (NH 3) emission sources in the livestock industry. Here, we present the first meta-analysis and integrated assessment of NH 3 emissions and mitigation potentials for typical broiler litter manure management system (MMS) and layer manure belt MMS based on data from 96 studies. A total of 10 integrated NH 3 emission factors (EFs) and the NH 3 mitigation efficiencies (MEs) of 14 available options were provided. The estimated NH 3 emissions from the baseline scenarios of the broiler litter MMS and the layer manure belt MMS were 84.1 ± 5.9 kg AU−1 yr−1 and 53.5 ± 15.8 kg AU−1 yr−1, respectively. The NH 3 mitigation for the broiler litter MMS should be focused on the in-house stage, while the mitigation in the layer manure belt MMS should be focused on the outdoor and land application stages. The recommended NH 3 mitigation options for the in-house stage, the outdoor stage and the land application stage were acid scrubber (−92.5%), compost biofilter (−71.9%) and changing the manure surface application to incorporation (−83.0%), respectively. The recommended mitigation combinations of low crude protein (LCP) diet, acid scrubber, compost biofilter and manure incorporation achieved the highest NH 3 mitigation efficiency from both broiler litter MMS and layer manure belt MMS, by 89.3% and 84.8%, respectively. The results of this study have important implications for developing sustainable poultry production systems from the viewpoint of NH 3 mitigation. The environment issues such as the other reactive nitrogen emissions and the greenhouse gas (GHG) emissions should also be considered in the future. [ABSTRACT FROM AUTHOR]

Emissions of ammonia (NH 3 ) and greenhouse gases (GHG) from digested pig manure storage have negative agronomic and environmental implications. The study was undertaken to evaluate how temperature affects NH 3 , GHG (i.e., methane (CH 4 ) and nitrous oxide (N 2 O)) and nitric oxide (NO) emitted from a pig manure based biogas digester effluent (BDE) storage system. Six groups of 125 L of BDE were stored in triplicate for 99 days at 5, 10, 15, 20, 25 °C and uncontrolled temperature condition (UT: temperature ranged from 32 °C to 20 °C) for gas monitoring using the dynamic emission vessel method. BDE characteristics were analyzed weekly during the storage. The results showed that all gas emissions were extremely low for the 5, 10 and 15 °C regimens. The critical temperature for N 2 O and NO emissions from BDE storage was 25 °C. As the temperature increased from 5 °C to 25 °C, the N loss ratio increased from 8.9% to 41.9%, and NH 3 was the main nitrogen loss form, accounting for 4.4–34.9% of the TN. The overall GHG emissions were dominated by N 2 O, which accounted for more than 53% of the CO 2 -eq emissions for all of the regimens. The CH 4 emission factor was 0.001–0.019 L g −1 VS; the N 2 O emission factor was in the range of 0.0003–0.0007 kg N 2 O–N kg −1 N for 5, 10, 15 and 20 °C regimens, while being 0.0038 and 0.0016 kg N 2 O–N kg −1 N for 25 °C and UT regimens, respectively. The results indicate that NH 3 and N 2 O are the two major gas emissions from BDE storage, and the future research on mitigation for BDE storage should focus more on N 2 O and NH 3 . [ABSTRACT FROM AUTHOR]