Ammonia Concentrations In Air Research Articles

Integrated assessment of agricultural practices on large scale losses of ammonia, greenhouse gases, nutrients and heavy metals to air and water.

To gain insight in the environmental impacts of crop, soil and nutrient management, an integrated model framework INITIATOR was developed predicting: (i) emissions of ammonia (NH3) and greenhouse gases (GHG) from agriculture, including animal husbandry and crop production and (ii) accumulation, leaching and runoff of carbon, nutrients (nitrogen, N, phosphorus, P, and base cations) and metals in or from soils to groundwater and surface water in the Netherlands. Key processes in soil are included by linear or non-linear process formulations to maintain transparency and to enable data availability for spatially explicit application from field up to national level. Calculated national trends in nutrient losses over 2000-2020 compared well with independent estimates and showed a reduction in N and P input of 26 to 33 %, whereas the surplus declined by 33 % for N and 86 % for P due to increased crop yields and reduced inputs. This was accompanied by a reduction of 30-35 % in atmospheric emissions of ammonia and nitrous oxide as well a decline in N and P runoff of 35 and 10 %, respectively, whereas the emission of methane increased with 4 %. Model results compared well with (i) large scale observations of ammonia concentrations in air and nitrate concentrations in upper groundwater and ditch water, (ii) with nitrous oxide emissions and phosphorus adsorption in experiments at field scale and (iii) with metal adsorption in large scale soil datasets. Various mitigation measures were evaluated in view of policy ambitions for climate, soil and environmental quality for 2030, i.e. a reduction of 50 % for NH3, 11-17 % for GHG, 20 % for N runoff and 40 % for P runoff and an ambition of 50 % GHG emission reduction for 2050. The measures focused on a combination of animal feeding, low emission housing and application technologies, improved crop, soil and nutrient management, all being applied with an effectiveness of 100 % and 50 %, respectively. In addition, we evaluated impacts of 50 % livestock reduction, and combination scenarios of measures and livestock reduction. Full implementation of all measures can reduce NH3 emission, N leaching and N runoff by approximately 40-50 % and GHG emissions by approximately 30 %, but there is less potential to reduce P runoff, being <10 %. The combination of a more likely 50 % implementation/effectiveness of measures with 25 % livestock reduction leads to a comparable reduction. Required reductions from Dutch agriculture seem not possible with improved management only, but also requires livestock reduction, especially when the NH3 ambitions at the short term (2030) and the climate ambitions for the long term (2050) should be attained.

Modeling of Environmental Pollution by Ammonia Emission from a Damaged Pipeline

Purpose. This work provides for the development of a hydraulic model for calculating the unsteady ammonia outflow from a damaged pipeline and the implementation of this model into a numerical model for predicting emergency air pollution. Methodology. To solve the problem, the calculated dependencies of the pressure flow hydraulics were used. An empirical model to calculate the evaporation of ammonia from a damaged pipeline was also used. To calculate the process of spreading ammonia in atmospheric air, a three-dimensional equation of convective-diffusion transfer of impurities was used. Mathematical modeling of the spread of ammonia from a damaged pipeline takes into account the change with height of the wind flow velocity, as well as the change with height of the vertical coefficient of atmospheric diffusion, the dynamics of changes over time in the intensity of ammonia leakage from the damaged pipeline. For the numerical solution of the three-dimensional differential equation for the transfer of ammonia in atmospheric air, its physical splitting is carried out: an equation that describes the transport of an impurity due to convection is singled out separately, an equation that describes the transport of an impurity due to atmospheric diffusion and separately an equation that describes a change in the ammonia concentration in air due to the action of the emission source. The McCormack method is used to numerically integrate the equation for the convective transfer of ammonia in air. The Richardson method is used to numerically integrate the equation of diffusion transfer of an impurity. The Euler method is used to numerically integrate the equation that describes the change in ammonia concentration under the influence of an emission source. Findings. Based on the developed model of unsteady ammonia outflow from the damaged pipeline and the created numerical model of ammonia propagation in the atmospheric air, a computational experiment was carried out to assess the level of atmospheric air and underlying surface pollution in the event of an emergency ammonia outflow in the section where the Tolyatti – Odessa ammonia pipeline crosses the Dnipro River. Data on non-stationary environmental pollution were obtained. Originality. A mathematical model that allows calculating the unsteady process of ammonia outflow from a damaged pipeline has been developed. A numerical model is proposed to determine the areas of contamination during an emergency ammonia outflow from the Tolyatti – Odessa ammonia pipeline. Practical value. Based on the developed model, a code has been created that makes it possible to promptly predict the environmental pollution dynamics during an emergency ammonia outflow. The proposed mathematical model can be used in the development of emergency response plan for chemically hazardous facilities.

Thin films of poly(oxyethylene)-substituted phthalocyaninato zinc(II) and oxotitanium(IV) complexes: synthesis, structure and sensor response to ammonia

In this work, the effect of chloro-substitution in poly(oxyethylene)-substituted phthalocyaninato zinc(II) and oxotitanium(IV) complexes on the ordering and sensor response of their thin films to ammonia was studied. Thin films of thia-bridged tetrapoly(oxyethylene)- and tetrachlorotetrapoly(oxyethylene)-substituted zinc and titanyl Pcs forming mesophases in wide temperature range were spun onto glass slides with interdigitated electrodes to test their chemiresistive sensor response to ammonia in the concentration range from 1 to 50 ppm. It was shown by the methods of UV–Vis, polarized Raman spectroscopy and polarized optical microscopy that these phthalocyanines formed thin films with different orientation and ordering in dependence on their molecular structure. The introduction of chloride substituents into the phthalocyanine ring was found to lead to the increase of the chemiresistive sensor response of both zinc and oxotitanium phthalocyanine films toward low concentrations of ammonia in air.

Role of ammonia in European air quality with changing land and ship emissions between 1990 and 2030

Abstract. The focus of this modeling study is on the role of ammonia in European air quality in the past as well as in the future. Ammonia emissions have not decreased as much as the other secondary inorganic aerosol (SIA) precursors – nitrogen oxides (NOx) and sulfur dioxide (SO2) – since the 1990s and are still posing problems for air quality and the environment. In this study, air quality simulations were performed with a regional chemical transport model at decadal intervals between 1990 and 2030 to understand the changes in the chemical species associated with SIA under varying land and ship emissions. We analyzed the changes in air concentrations of ammonia, nitric acid, ammonium, particulate nitrate and sulfate as well as changes in the dry and wet deposition of ammonia and ammonium. The results show that the approximately 40 % decrease in SIA concentrations between 1990 and 2010 was mainly due to reductions in NOx and SO2 emissions. The ammonia concentrations on the other hand decreased only near the high-emission areas such as the Netherlands and northern Italy by about 30 %, while there was a slight increase in other parts of Europe. Larger changes in concentrations occurred mostly during the first period (1990–2000). The model results indicate a transition period after 2000 for the composition of secondary inorganic aerosols due to a larger decrease in sulfate concentrations than nitrate. Changes between 2010 and 2030 – assuming the current legislation (CLE) scenario – are predicted to be smaller than those achieved earlier for all species analyzed in this study. The scenario simulations suggest that if ship emissions will be regulated more strictly in the future, SIA formation will decrease especially around the Benelux area, North Sea, Baltic Sea, English Channel and the Mediterranean region, leaving more ammonia in the gas phase, which would lead to an increase in dry deposition. In the north of the domain, the decrease in SIA would be mainly due to reduced formation of particulate nitrate, while the change around the Mediterranean would be caused mainly by decreased sulfate aerosol concentrations. One should also keep in mind that potentially higher temperatures in the future might increase the evaporation of ammonium nitrate to form its gaseous components NH3 and HNO3. Sensitivity tests with reduced NOx and NH3 emissions indicate a shift in the sensitivity of aerosol formation from NH3 towards NOx emissions between 1990 and 2030 in most of Europe except the eastern part of the model domain.

The Influence of the Mineral–Microbial Deodorizing Preparation on Ammonia Emission and Growth Performance in Turkey Production

In our previous in vitro research and also in laying hen production, attempts were made to minimise ammonia emissions in poultry houses with the use of Deodoric® biopreparation. The objective of the present research was to evaluate the influence of the Deodoric® on ammonia (NH3) emission and turkey growth performance in a semi-industrial production system. Significant differences in NH3 emission (p-value &lt; 0.001), body weight (p-value &lt; 0.001) and relative humidity (p-value &lt; 0.001) were observed between the control group (C) and the experimental group (E) where Deodoric® was applied. In group C, an increase in ammonia concentration in air could have contributed to a decrease in the body weight of turkeys, but the above correlation was not observed in group E. In the control group, a relatively strong correlation between NH3 emission and temperature (p-value = 0.0009; r = 0.74) and moderate correlations between NH3 emission vs. relative humidity (p-value = 0.01; r = 0.59), air speed (p-value = 0.015; r = 0.60) and cooling (p-value = 0.005; r = 0.66) were noted. Studied correlations were not observed in group E. The preparation did not affect microbial levels in manure or body samples. Throughout the experiment, significant differences in the number of mesophilic bacteria (for the model: F = 46.14, p-value = 0.09; for mesophilic microorganisms: F = 3.29, p-value = 0.045) and Campylobacter spp. (for the model: F = 24.96, p-value = 0.008; for Campylobacter spp.: F = 0.25, p-value = 0.64) were not observed between group C and group E. The administration of Deodoric® to manure decreased NH3 concentration in the air and increased weight gains in the experimental group of turkeys relative to group C. Preparation may be applied in poultry farms to improve poultry farming conditions.

English

English

Total deposition of nitrogen in Swiss forests: Comparison of assessment methods and evaluation of changes over two decades

Atmospheric nitrogen (N) deposition in terrestrial ecosystems is difficult to quantify, especially in forests. In this study, we compared three approaches for determining the wet and dry deposition of nitrogen (total deposition) at 17 intensively monitored forest sites in Switzerland. Specifically, we considered approaches based on: 1) measurements of bulk deposition and throughfall in 2014 (throughfall method); 2) measurements of bulk deposition and measurements of air concentrations of ammonia (NH3) and nitrogen dioxide (NO2), to which deposition velocities were applied, also in 2014 (inferential method); and 3) a model developed for Switzerland at a high spatial resolution, run for the five-year period 2013–2017 (emission based model). In addition, changes over two decades were assessed using continuous measurements of throughfall and bulk deposition. Further, air concentrations of NH3 and NO2 measured in 2014 were compared with concentrations measured in 2000 at 10 of the sites. The three approaches generally yielded comparable estimates of total deposition, with some notable differences at some sites. For both the model and the inferential method, uncertainties were related to the deposition velocities that were applied to air concentrations of N compounds, especially for NH3. The throughfall method provided a minimum estimate of the total N deposition in the forest, but the fraction of the deposited N that is directly taken up by the canopy remained difficult to quantify. Nitrogen deposition has decreased since the mid-1990s at the majority of the sites. However, deposition of the reduced forms of N seems to have stagnated at the local level. Furthermore, N deposition is still too high in comparison with the range of empirical critical loads of N (CLN). The minimum deposition estimated from throughfall exceeds the lower limit of CLN at all sites except those in the Central Alps. Deposition estimated with the model and the inferential method exceeds the lower limit of CLN at all sites and even exceeds the upper limit at several locations.

A Water-Stable Proton-Conductive Barium(II)-Organic Framework for Ammonia Sensing at High Humidity.

In view of environmental protection and the need for early prediction of major diseases, it is necessary to accurately monitor the change of trace ammonia concentration in air or in exhaled breath. However, the adoption of proton-conductive metal-organic frameworks (MOFs) as smart sensors in this field is limited by a lack of ultrasensitive gas-detecting performance at high relative humidity (RH). Here, the pellet fabrication of a water-stable proton-conductive MOF, Ba( o-CbPhH2IDC)(H2O)4] n (1) ( o-CbPhH4IDC = 2-(2-carboxylphenyl)-1 H-imidazole-4,5-dicarboxylic acid) is reported. The MOF 1 displays enhanced sensitivity and selectivity to NH3 gas at high RHs (>85%) and 30 °C, and the sensing mechanism is suggested. The electrochemical impedance gas sensor fabricated by MOF 1 is a promising sensor for ammonia at mild temperature and high RHs.

Superior NH3Sensor Using Ni Doped K-OMS-2 Nanofibers

A room temperature reversible ammonia (NH3) gas sensor based on the resistive transduction mechanism comprising of thin film of nickel doped cryptomelane octahedral molecular sieves of K-OMS-2 nanofibers is developed. Ni-OMS2 demonstrated excellent and persistent sensing toward the low concentration of ammonia in air at room temperature. The sensor showed strong response of 20% and 57% for 10 and 50 ppm of NH3. No heating was required either for sensing or recovery. Doping concentration of Ni significantly affect the ammonia sensing properties of nanofibers. Low doping of 0.11 Ni+2 in K-OMS-2 resulted in the major improvement in recovery time during ammonia sensing to 40s from 87s in undoped nanofibers. However, higher amount of Ni doping showed no response for ammonia sensing.

Investigation of Pristine Graphite Oxide as Room-Temperature Chemiresistive Ammonia Gas Sensing Material.

Graphite oxide has been investigated as a possible room-temperature chemiresistive sensor of ammonia in a gas phase. Graphite oxide was synthesized from high purity graphite using the modified Hummers method. The graphite oxide sample was investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetry and differential scanning calorimetry. Sensing properties were tested in a wide range of ammonia concentrations in air (10–1000 ppm) and under different relative humidity levels (3%–65%). It was concluded that the graphite oxide–based sensor possessed a good response to NH3 in dry synthetic air (ΔR/R0 ranged from 2.5% to 7.4% for concentrations of 100–500 ppm and 3% relative humidity) with negligible cross-sensitivity towards H2 and CH4. It was determined that the sensor recovery rate was improved with ammonia concentration growth. Increasing the ambient relative humidity led to an increase of the sensor response. The highest response of 22.2% for 100 ppm of ammonia was achieved at a 65% relative humidity level.

Superior, rapid and reversible sensing activity of graphene-SnO hybrid film for low concentration of ammonia at room temperature

A room temperature reversible ammonia (NH3) gas sensor based on resistive transduction mechanism was fabricated using SnO coated graphene film. This hybrid material was prepared by heating few layer graphene in air followed by heating in aqueous solution of SnCl2. The graphene-SnO hybrid demonstrated excellent and persistent sensing towards the low concentration of ammonia in air. The sensor showed response and recovery time 10% and 21% for 20ppm and 50ppm of NH3. No heating was required either for sensing or recovery. Reversible charge transfer between NH3 and Sn connected to graphene through oxygen, and high electrical conductivity of graphene are proposed to be responsible for high sensitivity of the hybrid film towards ammonia gas. The hybrid material showed >8months stability and sensing ability.

Investigation of Ammonia Gas Sensing Properties of Graphite Oxide

In this paper a graphite oxide is investigated as a possible sensing layer of room temperature ammonia chemiresistive gas sensor. The sensing properties were tested in a wide range of ammonia concentrations in air (10-1000ppm) and under different humidity levels (3-65%). It was concluded that the graphite oxide based sensor possessed high response to NH3 in synthetic air (ΔR/R0 ranged from 2.5 to 7.4% for concentrations of 100-500ppm and 3% relative humidity) with negligible cross-sensitivity towards H2 and CH4. It was determined that the sensor recovery rate was improved with ammonia concentration growth. Increasing of ambient relative humidity led to increase of sensor response. The highest response of 22.2% for 100ppm of ammonia was achieved at 65% relative humidity level.

Lichen response to ammonia deposition defines the footprint of a penguin rookery

Ammonia volatilized from penguin rookeries is a major nitrogen source in Antarctic coastal terrestrial ecosystems. However, the spatial extent of ammonia dispersion from rookeries and its impacts have not been quantified previously. We measured ammonia concentration in air and lichen ecophysiological response variables proximate to an Adelie penguin rookery at Cape Hallett, northern Victoria Land. Ammonia emitted from the rookery was 15N-enriched (δ15N value +6.9) and concentrations in air ranged from 36–75 µg m−3 at the rookery centre to 0.05 µg m−3 at a distance of 15.3 km. δ15N values and rates of phosphomonoesterase (PME) activity in the lichens Usnea sphacelata and Umbilicaria decussata were strongly negatively related to distance from the rookery and PME activity was positively related to thallus N:P mass ratio. In contrast, the lichen Xanthomendoza borealis, which is largely restricted to within an area 0.5 km from the rookery perimeter, had high N, P and 15N concentrations but low PME activity suggesting that nutrient scavenging capacity is suppressed in highly eutrophicated sites. An ammonia dispersion model indicates that ammonia concentrations sufficient to significantly elevate PME activity and δ15N values (≥0.1 µg NH3 m−3) occurred over c. 40–300 km2 surrounding the rookery suggesting that penguin rookeries potentially can generate large spatial impact zones. In a general linear model NH3 concentration and lichen species identity were found to account for 72 % of variation in the putative proportion of lichen thallus N originating from penguin derived NH3. The results provide evidence of large scale impact of N transfer from a marine to an N-limited terrestrial ecosystem.

Nanoporous carbons as gas sensors: Exploring the surface sensitivity

Ammonia sensing properties of a poly(sodium 4-styrene sulfonate) derived carbon and its air oxidized counterpart were studied. The carbons were used to fabricate chips-like devices that were further used for electrical resistance measurements when exposed to various concentrations of dry ammonia. The sulfur-containing carbon after oxidation had a nine times greater response to ammonia than before oxidation. This response was evaluated from the point of view of reactive adsorption and physisorption. The initial reactions of ammonia with the sulfonic groups on the non-oxidized carbon led to an irreversible increase in resistance, while on the oxidized carbon, deprived of sulfonic groups, physisorption caused an opposite effect. After equilibration and reactive adsorption, a reversible decrease in resistance upon exposure to ammonia was found on both samples. The extensive characterization of the carbons’ surfaces, and their performance as ammonia adsorbents, suggest that the sensing mechanism is governed by the physical adsorption of ammonia inside the micropores. Higher concentration of ammonia in air results in more pores being filled and thus, in the stronger response of the sensor.

Enhancing the sensitivity of chemiresistor gas sensors based on pristine carbon nanotubes to detect low-ppb ammonia concentrations in the environment

The possibility of using novel architectures based on carbon nanotubes (CNTs) for a realistic monitoring of the air quality in an urban environment requires the capability to monitor concentrations of polluting gases in the low-ppb range. This limit has been so far virtually neglected, as most of the testing of new ammonia gas sensor devices based on CNTs is carried out above the ppm limit. In this paper, we present single-wall carbon nanotube (SWCNT) chemiresistor gas sensors operating at room temperature, displaying an enhanced sensitivity to NH3. Ammonia concentrations in air as low as 20 ppb have been measured, and a detection limit of 3 ppb is demonstrated, which is in the full range of the average NH3 concentration in an urban environment and well below the sensitivities so far reported for pristine, non-functionalized SWCNTs operating at room temperature. In addition to careful preparation of the SWCNT layers, through sonication and dielectrophoresis that improved the quality of the CNT bundle layers, the low-ppb limit is also attained by revealing and properly tracking a fast dynamics channel in the desorption process of the polluting gas molecules.

Farm nitrogen balances in six European landscapes as an indicator for nitrogen losses and basis for improved management

Abstract. Improved management of nitrogen (N) in agriculture is necessary to achieve a sustainable balance between the production of food and other biomass, and the unwanted effects of N on water pollution, greenhouse gas emissions, biodiversity deterioration and human health. To analyse farm N-losses and the complex interactions within farming systems, efficient methods for identifying emissions hotspots and evaluating mitigation measures are therefore needed. The present paper aims to fill this gap at the farm and landscape scales. Six agricultural landscapes in Poland (PL), the Netherlands (NL), France (FR), Italy (IT), Scotland (UK) and Denmark (DK) were studied, and a common method was developed for undertaking farm inventories and the derivation of farm N balances, N surpluses and for evaluating uncertainty for the 222 farms and 11 440 ha of farmland included in the study. In all landscapes, a large variation in the farm N surplus was found, and thereby a large potential for reductions. The highest average N surpluses were found in the most livestock-intensive landscapes of IT, FR, and NL; on average 202 ± 28, 179 ± 63 and 178 ± 20 kg N ha−1 yr−1, respectively. All landscapes showed hotspots, especially from livestock farms, including a special UK case with large-scale landless poultry farming. Overall, the average N surplus from the land-based UK farms dominated by extensive sheep and cattle grazing was only 31 ± 10 kg N ha−1 yr−1, but was similar to the N surplus of PL and DK (122 ± 20 and 146 ± 55 kg N ha−1 yr−1, respectively) when landless poultry farming was included. We found farm N balances to be a useful indicator for N losses and the potential for improving N management. Significant correlations to N surplus were found, both with ammonia air concentrations and nitrate concentrations in soils and groundwater, measured during the period of N management data collection in the landscapes from 2007–2009. This indicates that farm N surpluses may be used as an independent dataset for validation of measured and modelled N emissions in agricultural landscapes. No significant correlation was found with N measured in surface waters, probably because of spatial and temporal variations in groundwater buffering and biogeochemical reactions affecting N flows from farm to surface waters. A case study of the development in N surplus from the landscape in DK from 1998–2008 showed a 22% reduction related to measures targeted at N emissions from livestock farms. Based on the large differences in N surplus between average N management farms and the most modern and N-efficient farms, it was concluded that additional N-surplus reductions of 25–50%, as compared to the present level, were realistic in all landscapes. The implemented N-surplus method was thus effective for comparing and synthesizing results on farm N emissions and the potentials of mitigation options. It is recommended for use in combination with other methods for the assessment of landscape N emissions and farm N efficiency, including more detailed N source and N sink hotspot mapping, measurements and modelling.

Trends in atmospheric ammonia and particulate ammonium concentrations in Sweden and its causes

Daily average air concentrations of ammonia plus particulate ammonium, nitric acid plus particulate nitrate, sulphur dioxide and particulate sulphate have been measured at four EMEP (European Monitoring and Evaluation Programme) sites in Sweden since 1986. From 1993 sampling was made with a filter pack that separates the gaseous and particulate forms. The separation is not perfect, but fairly good when compared to a denuder. The same filter pack was used for monthly measurements at four high altitude sites in the Swedish mountain areas. The concentration of particulate ammonium decreases more rapidly than the ammonia emissions in Sweden and neighbouring countries while the ammonia concentration increases. Particulate ammonium is mainly long-range transported from the continent to the southern parts of Sweden, while gaseous ammonia comes from all directions. The particulate ammonium concentrations are charged balanced with particulate sulphate and nitrate concentrations and the long-range transport is therefore limited by the availability of these anions.

Development and evaluation of optical fiber NH3 sensors for application in air quality monitoring

Ammonia is a major air pollutant emitted from agricultural practices. Sources of ammonia include manure from animal feeding operations and fertilizer from cropping systems. Sensor technologies with capability of continuous real time monitoring of ammonia concentration in air are needed to qualify ammonia emissions from agricultural activities and further evaluate human and animal health effects, study ammonia environmental chemistry, and provide baseline data for air quality standard. We have developed fiber optic ammonia sensors using different sensing reagents and different polymers for immobilizing sensing reagents. The reversible fiber optic sensors have detection limits down to low ppbv levels. The response time of these sensors ranges from seconds to tens minutes depending on transducer design. In this paper, we report our results in the development and evaluation of fiber optic sensor technologies for air quality monitoring. The effect of change of temperature, humidity and carbon dioxide concentration on fiber optic ammonia sensors has been investigated. Carbon dioxide in air was found not interfere the fiber optic sensors for monitoring NH3. However, the change of humidity can cause interferences to some fiber optic NH3 sensors depending on the sensor's transducer design. The sensitivity of fiber optic NH3 sensors was found depends on temperature. Methods and techniques for eliminating these interferences have been proposed.

Airborne enteric micro-organisms and ammonia levels in diaper-changing rooms in kindergartens

We evaluated risks associated with diaper changing in Finnish kindergartens where children were using either modern disposable paper or reusable cloth diapers. We determined enteric micro-organisms and ammonia in diaper-changing rooms in four kindergartens in autumn and winter in the ambient air. No coliphages were detected in the air. The numbers of faecal coliforms and enterococci in air were typically low regardless of whether the children used either paper or cloth diapers. Ammonia concentrations increased over the background level because of diaper changing. The numbers of bacteria or coliphages are not expected to pose any high air hygiene risks, and increased ammonia air concentrations are unlikely to impair the health of staff or children when diapers are changed in modern kindergartens. However, increased ammonia gas concentrations indicate that some other diaper-related gas-phase emissions should be studied to understand better diaper-related health risks. Modern reusable cloth baby diapers and the modern paper baby diapers used in this study are equally safe with respect to risks from airborne virus, bacteria or ammonia.

Evaluation of the NH3 Removal Efficiency of an Acid Packed Bed Scrubber Using Two Methods: A Case Study in a Pig Facility

The use of air cleaning systems to reduce ammonia emissions from animal houses is increasing. These systems are normally used in order to comply with local or national regulations of ammonia emission. Therefore, accurate determination of the proportion of ammonia being removed by these systems is crucial. There are two main methods available to measure ammonia removal efficiency of scrubbers: air balance (based on the measurement of ammonia concentrations in air) and combined water-air balance (in which it is also necessary to determine the amount of nitrogen recovered in the liquid phase). The first method is simpler to establish, while the second method might provide deeper information about the processes occurring. The main aim of this work was to assess, in terms of the variability of the results, the use of these two methods to evaluate the efficiency of an acid packed bed scrubber on a pig farm. An acid packed bed scrubber (70% NH3 removal) was monitored during ten complete 24 h cycles for ammonia concentrations, airflow rates, and nitrogen accumulation in the acid solution basin. The average efficiency calculated using the air balance method was 71% (4%), close to the design value of 70%, while the average efficiency when using the combined water-air balance method was 255% (53%). The accumulation and precipitation of ammonium salts in the packing material seem to be the main cause of the high variability and inaccuracy of the combined water-air balance method observed for this type of scrubber. According to these results, it is recommended to use the air balance method when determining the ammonia removal efficiency for acid packed bed scrubbers similar to the one studied here. According to the variability of the results observed in this work, at least 24 measurement days are needed in order to keep the relative error below 5% when using the air balance method to determine the ammonia removal efficiency of an acid packed bed scrubber.