Acid Scrubber Research Articles

Leveraging organic acids in bipolar membrane electrodialysis (BPMED) can enhance ammonia recovery from scrubber effluents

While air stripping combined with acid scrubbing remains a competitive technology for the removal and recovery of ammonia from wastewater streams, its use of strong acids is concerning. Organic acids offer promising alternatives to strong acids like sulphuric acid, but their application remains limited due to high cost. This study proposes an integration of air stripping and organic acid scrubbing with bipolar membrane electrodialysis (BPMED) to regenerate the organic acids. We compared the energy consumption and current efficiency of BPMED in recovering dissolved ammonia and regenerating sulphuric, citric, and maleic acids from synthetic scrubber effluents. Current efficiency was lower when regenerating sulphuric acid (22 %) compared to citric (47 %) and maleic acid (37 %), attributable to the competitive proton transport over ammonium across the cation exchange membrane. Organic salts functioned as buffers, reducing the concentration of free protons, resulting in higher ammonium removal efficiencies with citrate (75 %) and malate (68 %), compared to sulphate (29 %). Consequently, the energy consumption of the BPMED decreased by 54 % and 35 % while regenerating citric and maleic acids, respectively, compared to sulfuric acid. Membrane characterisation experiments showed that the electrical conductivity ranking, ammonium citrate > ammonium malate > ammonium sulphate, was mirrored by the energy consumption (kWh/kg-N recovered) ranking, ammonium sulphate (15.6) < ammonium malate (10.2) < ammonium citrate (7.2), while the permselectivity ranking, ammonium sulphate > ammonium citrate > ammonium malate, aligned with calculated charge densities. This work demonstrates the potential of combining organic acid scrubbers with BPMED for ammonium recovery from wastewater effluents with minimum chemical input.

Pilot study on gaseous pollution removal efficiency of acid scrubbing in a broiler house

The poultry industry is a major source of odor pollution and has received significant attention because of its impact on air quality and human health. Acid scrubbing has been widely used in livestock houses to remove ammonia (NH3), but this method has not been optimized for other odorous compounds, such as volatile organic compounds (VOCs). In this study, on-farm acid scrubbing equipment was operated in an experimental closed broiler house to determine the removal efficiency of gaseous pollution. The equipment was applied to the broiler exhaust system. The pH value and the gas residence time (gRT) were evaluated using central composite design and response surface methodology to establish a quadratic regression NH3 removal model and to reduce emissions of VOCs and greenhouse gases under field conditions. The results showed that at gRT of 1.7 s and pH of 4.0 were the optimal process parameters. Under optimal treatment conditions, the NH3 removal efficiency reached a maximum of 83.4%. Oxygenated VOC (OVOC) removal efficiency affected the removal of other components, such as hydrocarbons, aromatic hydrocarbons, and sulfides by dissolving into the organic aqueous solution. The results indicate that OVOCs might be the key factors influencing the removal of total VOCs. The removal efficiencies of acetaldehyde, dimethyl disulfide, methyl mercaptan, methyl sulfide, acetone, ethane, propane, and CO2 under the optimal process were 90.6%, 69.5%, 81.7%, 100%, 97.5%, 84.3%, 70.6%, and 54.7%, respectively. The methane removal efficiency was undetermined because of the undetectable inlet concentration. This method can provide a basis for the application of acid scrubber equipment and technical support for collaborative treatment of gaseous pollutants in livestock houses.

Nutrient recovery from wastewater: A review on the integrated Physicochemical technologies of ammonia stripping, adsorption and struvite precipitation

• A review on technical integration for N-P-K recovery was performed. • “Stripping → K-struvite precipitation” can recover N, P and K simultaneously. • Crystal size should be enlarged for upscaling “stripping + struvite precipitation”. • (Modified-)biochar/zeolite have been used as the seed of struvite or adsorbent. • Adsorbent could replace sulfuric acid in acid scrubber following stripping column. The field of wastewater management has seen a transition from “contaminant removal” in wastewater treatment plants (WWTPs) to “nutrient recovery” in so-called water resource recovery facilities (WRRFs) for years. For achieving a higher efficiency and economic benefits, the integration of multiple nutrient recovery technologies (NRTs) is of increased interest. This study provides a comprehensive overview of the integration of ammonia stripping, adsorption and struvite precipitation, three of the most dominant physicochemical NRTs. In their different combinations, a critical comparison of the available research is given from the perspective of process technical description, the current scale of application and potential challenges and perspectives ahead. The integration between ammonia stripping and struvite precipitation has been applied in either “one single integrated reactor” at lab scale or “multiple discrete reactors” at pilot/full scale. The collection of struvite should be further optimized, and “stripping → K-struvite precipitation” is expected to recover all of three macronutrients. In the technical integration between struvite precipitation and adsorption, small pristine adsorbents (<50 μm) have been used as the seeding material for struvite, while pristine and surface-modified adsorbents have been integrated with struvite precipitation as the sorbent material. Some magnesium-modified adsorbents achieved a higher removal efficiency and adsorption capacity than pristine adsorbent. The non-preferential adsorption is one of the main challenges limiting its upscaling. Lastly, stripping has been applied in the regeneration process of zeolite. Its economic benefits should be further analysed before its upscaling. This review proposed to apply adsorbents as the alternative of sulfuric acid in the acid scrubber following the stripping column. This new perspective may decrease the cost on ammonia stripping.

Environmental impact of pig production affected by wet acid scrubber as mitigation technology

Ammonia (NH 3 ) is the most common air pollutant in pig farms, affecting animals and workers’ health, and causing damages to ecosystems. Hence, there is a need to reduce NH 3 emissions. Many mitigation strategies can be applied to limit gaseous emissions, such as the application of air treatment technologies. In this study, the environmental impact of a typical Italian pig farm, adopting a wet acid scrubber to abate NH 3 emissions, was evaluated using the Life Cycle Assessment approach. 1 kg of live weight (LW) was selected as Functional Unit. Two scenarios were considered. The baseline scenario (BS) represents the situation as it is, while the alternative scenario (AS) a wet scrubber prototype (with 70% NH 3 removal efficiency) was adopted. For 8 of the 12 evaluated impact categories, AS shows the highest environmental impact, due to the scrubber construction and maintenance. However, it was the best for those impact categories most affected by NH 3 . Observed reduction ranged from 10% (for acidification, TA, and terrestrial eutrophication, TE) to 0.4% (for marine eutrophication, ME). The climate change impact was 3.55 kg CO 2 eq kg -1 LW and 3.65 kg CO 2 eq kg -1 LW for BS and AS, respectively. For almost all impact categories, the consumable materials for wet scrubber operation represented around 85% of the total impact of the scrubber. The results of the sensitivity analysis showed that variation in NH 3 removal efficiency had the greatest effect on particulate matter formation, TA, and TE. The achieved results provide a first quantitative indication of the environmental benefits that can be achieved using wet acid scrubber in naturally ventilated pig facilities.

Evaluation of a Wet Acid Scrubber and Dry Filter Abatement Technologies in Pig Barns by Dynamic Olfactometry

Livestock activities, in particular swine farms, are sources of odorant compounds that cause conflicts with the neighboring population. Beside the effects on the neighborhood, excessive odor emission can cause discomfort to farm workers. In this context the APPROAch project, aims to test the application of two different air cleaning technologies (a wet acid scrubber and a dry filter) to reduce dust, ammonia and odors, in naturally ventilated pig facilities. The aim of the present study is to evaluate, in a pig farm, the odor removal efficiency of the two tested abatement technologies, based on air samples analyzed by dynamic olfactometry. Odor sampling was carried out at a pig facility involved in the project and brought to the lab within 30 h from sampling, as established by the European Standard EN 13725:2004. Odor concentration was evaluated by dynamic olfactometry using an Olfaktomat-n 6 (PRA-Odournet B.V.—Amsterdam, The Netherlands). The results show that the wet acid scrubber prototype presents an average odor removal efficiency of 16%, whereas dry filter has from limited to no effect. This efficiency could be considered as a good result for a prototype even if further analysis, with longer sampling periods are needed.

Comparative life cycle assessment of technologies and strategies to improve nitrogen use efficiency in egg supply chains

A non-trivial challenge along egg supply chains is inefficient use of nitrogen, which may have a combination of negative economic, human/animal health, and environmental implications. A variety of technologies and management strategies have been proposed to improve nitrogen use efficiency (NUE) and reduce emissions at key supply chain stages. This study considered seven scenarios representing NUE strategies: (1) biochar addition to the soil and (2) application of the “4Rs” approach to fertilizer management in feed input production; (3) a reduced crude protein supplemented with synthetic amino acids diet; (4) use of acid scrubbers in poultry barns; (5) biochar addition to stored manure; (6) manure incorporation at the time of land application; and (7) joint application of all strategies. ISO 14044 compliant environmental life cycle assessment (LCA) along with NUE calculations were performed to analyze and compare these mitigation options. The functional unit was one tonne of egg production at the farm gate in Canada. The most significant increase in NUE (13%) resulted from the application of the scrubber in the layer barn. The scrubber also significantly lowered acidifying (21%) and eutrophying (16%) emissions compared to the baseline. The combined application of all strategies increased NUE by 15% compared to the baseline scenario and reduced acidification, global warming, and eutrophication potential, but at the cost of a large increase in energy consumption. Each strategy might be more or less suitable depending on the considered environmental impacts, as well as NUE outcomes. Use of LCA is essential to informed decision making in this context.

Improvement of human health and environmental costs in the European Union by air scrubbers in intensive pig farming

Intensive pig farming is responsible for significant air pollutant emissions. This study explores the effect that the large-scale implementation of air cleaning technologies (wet acid scrubbers) for pig housing facilities could have in the European Union. Emissions related to the housing stage of NH3, PM10, NMVOC and indirect N2O from large pig farms (>1000 heads of sows or fattening pigs) are first estimated in the actual situation (current scenario - CS), considering implementation rates and removal efficiencies of the different emission abatement techniques available. Subsequently, alternative scenarios (AS1 and AS2) are simulated with a growing implementation rate of the wet acid scrubber (35% and 65% of the concerned pig farms in all Member States). A comparison between the scenarios was carried out, taking into account emissions reduction, consumables for scrubber operation and environmental credit given by the avoidance of synthetic nitrogen fertilizer production. The annual impact on human health of 21,212 disability-adjusted life years (DALY) in CS was significantly reduced in AS1 (-15%) and in AS2 (-40%), showing that the environmental trade-off given by the consumables is largely overwhelmed by emission abatement. At the same time, the current environmental cost to society of the concerned emissions was estimated at 4154 million € per year (of which 89% due to NH3), which also was reduced in alternative scenarios (−668 and −1765 million € for AS1 and AS2). The abatement of NH3, on which the wet acid scrubber expresses the greatest removal efficiency, was fundamental in both reducing the human health impact and environmental costs, demonstrating the key environmental role of this pollutant and the growing need to find solutions for its containment in the EU.

Pig barns ammonia and greenhouse gas emission mitigation by slurry aeration and acid scrubber

Livestock production is associated with several gaseous pollutant emissions to the environment. These emissions can degrade local and regional air quality, contribute to surface water eutrophication and acid rain, and contribute to the greenhouse gas footprint of the production sector. Modern production systems must balance animal welfare and environmental pollution potential with economic reality, which is a great challenge to maintain as global demand for animal protein increases. Accordingly, gaseous emission technologies were the main target for this research, in which mitigating gas emissions of ammonia, nitrous oxide, and methane from pig production facilities via slurry aeration system was tested. Five treatments with different airflow rates in the test room were examined continuously over a period of 6weeks and the results were compared with the control room. Test results indicate that the highest mitigation potentials were 12, 57.6, and 10.4% for nitrous oxide, methane, and ammonia, respectively. Subsequently directing exhaust air into a sulfuric acid air scrubber at 3.0pH further reduced total ammonia emissions by 80 to 87%.

Evaluation and techno-economic analysis of packed bed scrubber for ammonia recovery from drying fumes produced during the thermal drying of sewage sludge

This study investigates the recovery of ammonia from drying fumes during thermal drying of sewage sludge with packed bed acid scrubbers to recover ammonia and to produce ammonium sulfate. The process is modelled for two concentrations, 75 and 100 ppm, and 1000m3/h inlet flowrate of drying fumes containing air and ammonia gas. It results in finding optimal parameters for scale-up of drying fumes during thermal drying of 7700t/a sewage sludge of Lappeenranta city. It is found that a single scrubber, with a 24000 m3/h of inlet gas and an ammonia concentration of 75 ppm, liquid to gas ratio of 1.5, temperature and pH of liquid acid as 100°C and 3 respectively, gives the efficiency of more than 99%, and reduces ammonia concentration in the outlet stream to 0.2 ppm. The capital cost is 290 k€, operating cost is 113k€/a, removal cost with and without revenue of ammonium sulfate is 20 €/t and 18 €/t of sludge. The packed bed acid scrubber would be suitable to remove ammonia in the drying fumes to recover ammonia from the drying fumes, but the initial economic analysis highlights that the production of commercial grade ammonium sulfate fertilizer would be an expensive option.

Ammonium recovery from model solutions and sludge liquor with a combined ion exchange and air stripping process

The recovery of ammonium (NH4+) from model (NH4)2SO4 solutions as well as from sludge liquor of a communal waste water treatment plant was studied on the laboratory scale using the ion exchanger loop stripping process (ILS). The ILS process combines ion exchange and air stripping in a hybrid process and works with fixed bed columns containing natural zeolite (mainly clinoptilolite), which is alternately loaded and regenerated. The sodium hydroxide (NaOH) regeneration fluid is simultaneously air stripped. Ammonium is recovered in a subsequent acid scrubber as concentrated ammonium sulfate solution, which is a suitable reducing agent for industrial NOx recovery. Lab scale experiments with four loading and regeneration cycles demonstrate the technical feasibility of the process. The ammonium equilibrium increased after the first loading and regeneration cycles and ammonium uptake reached concentrations of 3 to 4 mg NH4+ L−1 over four consecutive cycles. NaOH regeneration at pH values >11.5 recovered nearly the total amount of previously adsorbed ammonium. The stripped amount of NH4+ increased over the investigated cycles and in the final regeneration sequence approximately the whole amount of desorbed ammonium was simultaneously stripped. Ammonium exchange and recovery characteristics did not significantly change when real sludge liquor samples were used.

Mitigating ammonia emissions from typical broiler and layer manure management – A system analysis

Broiler and layer productions are important ammonia (NH3) emission sources in the livestock industry. Here, we present the first meta-analysis and integrated assessment of NH3 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 NH3 emission factors (EFs) and the NH3 mitigation efficiencies (MEs) of 14 available options were provided. The estimated NH3 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 NH3 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 NH3 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 NH3 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 NH3 mitigation. The environment issues such as the other reactive nitrogen emissions and the greenhouse gas (GHG) emissions should also be considered in the future.

Effects of Land-Applied Ammonia Scrubber Solutions on Yield, Nitrogen Uptake, Soil Test Phosphorus, and Phosphorus Runoff.

Ammonia (NH) scrubbers reduce amounts of NH and dust released from animal rearing facilities while generating nitrogen (N)-rich solutions, which may be used as fertilizers. The objective of this study was to determine the effects of various NH scrubber solutions on forage yields, N uptake, soil-test phosphorus (P), and P runoff. A small plot study was conducted using six treatments: (i) an unfertilized control, (ii) potassium bisulfate (KHSO) scrubber solution, (iii) aluminum sulfate [Al(SO) ⋅14HO, alum] scrubber solution, (iv) sodium bisulfate (NaHSO) scrubber solution, (v) sulfuric acid (HSO) scrubber solution, and (vi) ammonium nitrate (NHNO) fertilizer. The scrubber solutions were obtained from ARS Air Scrubbers attached to commercial broiler houses. All N sources were applied at a rate of 112 kg N ha. Plots were harvested approximately every 4 wk and soil-test P measurements were made, then a rainfall simulation study was conducted. Cumulative forage yields were greater ( < 0.05) for KHSO (7.6 Mg ha) and NaHSO (7.5 Mg ha) scrubber solutions than for alum (6.7 Mg ha) or HSO (6.5 Mg ha) scrubber solutions or for NHNO (6.9 Mg ha). All N sources resulted in higher yields than the control (5.1 Mg ha). The additional potassium in the KHSO treatment likely resulted in higher yields. Although Mehlich-III-extractable P was not affected, water-extractable P in soil was lowered by the alum-based scrubber solution, which also resulted in lower P runoff. This study demonstrates that N captured using NH scrubbers is a viable N fertilizer.

Comparing environmental impact of air scrubbers for ammonia abatement at pig houses: A life cycle assessment

Intensive livestock production involves environmental emissions and impacts, including emission of greenhouse gases and ammonia leading to climate change and terrestrial acidification. Ammonia emission from animal housing systems can be reduced by introducing air scrubbers for cleaning the exhaust air, but insight into the environmental impact throughout the entire system is lacking. This study aimed to assess and compare the environmental impact of three types of air scrubbers: an acid scrubber and two biotrickling filters, one with nitrification only and one with nitrification and denitrification. Air scrubbers were compared by using life cycle assessment and assessing five environmental impacts: climate change, terrestrial acidification, marine eutrophication, particulate matter formation and fossil fuel depletion. The acid scrubber showed reductions in all environmental impact categories (up to >2000%), whereas the biotrickling filter with combined nitrification and denitrification had highest climate change and fossil fuel depletion. The biotrickling filter with nitrification only had highest terrestrial acidification and marine eutrophication.

Comparision of the Bio-degradation of Trimethylamine by Hyphomicrobium Vulgare and Aminobacter Aminovorans

Trimethylamine (TMA) is the main responsible for the odor often associated with rotting fish and is one of the major sources of annoying odors generated in many industrial activities, like composting facilities, fish-meal manufacturing plants, wastewater treatment plants, landfills and livestock farms. Traditionally amines can be removed by acid scrubbers that require the continuous supply of acid and generates large amounts of wastewater. Biofiltration has been proved to be an effective and sustainable technology treating many odorous compounds but the efficient removal of TMA using biofilters has not been completely shown. There are different microorganisms with the ability to use TMA as nutrient for their growth and presents different rates of TMA bio-degradation and biomass yields. Between those Hyphomicrobium vulgare and Aminobacter aminovorans are two bacteria known for their capability to use TMA as carbon and energy source.In order to select one of these bacteria as inoculum for biofilters, TMA bio-degradation capacity of both bacteria was determinated in batch cultures. Each bacterium was cultivated at 30°C and 200 rpm in 125 ml shake flasks with a minimum mineral medium and TMA as source of carbon. To determine the effect of H2S on the biodegradation of TMA, H2S was added in the headspace of the flasks, the experiments were performed using 0, 20 and 70 ppm of H2S as initial concentration in headspace.The maximum biomass concentration obtained during the cultures was 1.17 g L-1 for Hyphomicrobium and0.44 g L-1 for A. aminovorans, it growth at a maximum specific growth rate of 0.15 h-1, higher than the obtained for Hyphomicrobium; 0.09 h-1. The biomass yield for TMA was 0.35 (g g-1) for Hyphomicrobium and 0.10 (g g- 1) for A. aminovorans. The specific consumption rate was 0.47 h-1 in the culture of A. aminovorans and 0.12 h- 1 in the culture of Hyphomicrobium. Although A. aminovorans shows higher TMA specific consumption rate than Hyphomicrobium, its biomass yield value (0.1 g g-1) indicates that in the case of A. aminovorans the carbon from TMA was metabolized to other products like carbon dioxide, formaldehyde or formate in detrimentof biomass production. The biodegradation of TMA by A. aminovorans is negatively affected by H2S, meanwhile in the case of Hyphomicrobium sp. the specific rate of biodegradation of TMA is positively influenced by the presence of H2S, making it even higher than the one obtained for A aminovorans without the presence of H2S. In conclusion, due to its specific growth rate and TMA specific consume rate Aminobacter aminovorans is a suitable candidate to be used as inoculum for biofilters designed for removing gas emissions containing TMA when there is not H2S in the mixture. However, if H2S is present, Hyphomicrobium vulgare would be the best choice for the inoculum or being part of the inoculum of the biofilter.

Development of MOS sensor-based NH3 monitor for use in poultry houses

To ensure poultry performance and welfare, ammonia (NH3) concentrations inside poultry houses have to be within acceptable limits; this requires regular NH3 monitoring. While there are low-cost, portable NH3 measuring devices have drawbacks. Due to its low cost, long lifetime, and short response time, a metal oxide semiconductor (MOS) sensor was used to develop a handheld NH3 monitor for use in poultry houses. Since the MOS sensor is affected by humidity and temperature, collocating relative humidity (RH) and temperature sensors with the MOS NH3 sensor and applying temperature and RH compensations greatly improved its performance. Compared to the boric acid scrubber, using broiler litter exhaust gas as the NH3 source, the relative error (RE) and coefficient of variation (CV) of the monitor averaged 7%, comparable to research-grade instruments. The monitor was more accurate than the electrochemical sensor and required less frequent purging. The response time of the unit was ∼1.5min, the total mass was <1.4kg while material cost was <$430. Hence, in addition to being convenient, the monitor provided accurate and precise measurements. With further refinements, the monitor has the potential to be used in poultry houses to control ventilation rates as a component of precision livestock farming to improve poultry performance and welfare.

Storage Method Impacts on Ammonia Flux from Broiler Cake and Acid Scrubbers for High Ammonia Concentration Measurements

Ammonia emissions from poultry farms, including waste stockpiles, can degrade the environment and may be regulated in the USA. The main purpose of this study was to see how different poultry waste storage methods impacted ammonia loss. During a 13-day lab study, ammonia flux from uncovered (Control), covered with an inexpensive blue tarpaulin (Tarp), and stockpiles twice the depth of the Control stockpiles (Double-depth) were compared. Ammonia concentrations in the exhaust airstream from the stockpiles were measured using boric acid scrubbers. Ammonia loss per unit surface from the Tarp treatment was 45 % lower than the other treatments, while on a volume basis, losses from the Tarp and Double-depth treatment were 45 % vs. the Control stockpile. A less-pervious cover might have reduced ammonia losses even more. Ammonia flux per unit area from the Control and Double-depth treatments were comparable to those from large stockpiles in a shed monitored in a companion study though flux per unit volume was much higher from the lab stockpiles due to larger surface area per unit volume. Therefore, compared with a flatter stockpile, a more compact stockpile with a lower surface area per unit volume would have lower ammonia loss. Ammonia diffusion from the core of the stockpile to the surface may control ammonia flux, even in larger stockpiles in the short term (≤15 days), with nitrogen mineralization playing a smaller role. The 250-mL 3 % boric acid scrubbers were suitable for sampling air streams with ammonia concentrations up to 1,000 mg m−3 at 25 °C. At 25 °C, three moles of boric acid seemed adequate for each mole of ammonia to be trapped.

Acidifier Dosage Effects on Inside Ammonia Concentrations in Roaster Houses

<abstract><title><italic>Abstract. </italic></title> Ammonia (NH₃) in broiler houses can degrade bird performance. Acidifier such as, sodium bisulfate (SBS) applied to litter inside broiler houses can reduce NH₃ release and thus improve bird performance. While there are multiple studies on acidifier effects on inside NH₃ concentrations in broiler houses, there are no studies in roaster houses where big broiler birds are grown for 8 to 12 wk. The impact of different SBS application rates - High (1.46 kg/m², whole house), Medium (0.73 kg/m², whole house), Low (0.49 kg/m², whole house), and Control (0.49 kg/m², brood chamber) on inside NH₃ concentrations was evaluated over six flocks of roaster chickens (~4 kg ea.). Ammonia concentrations were measured with acid scrubbers that sampled air at two locations (mid-house, end-house) 0.15 m above the litter. Inside NH₃ concentrations were much higher in the cool-season versus warm-season flocks. Generally, higher acidifier application rates provided better NH₃ suppression. Ammonia concentrations were ≤10 ppm during brooding, as well as for the entire duration of most warm-weather flocks with the High and Medium treatments. In the Low treatment, NH₃ concentrations were ≤25 ppm during brooding but approached or exceeded 25 ppm with the Control treatment. During brooding, the High, Medium, and Low treatments resulted in significantly lower mid-house NH₃ concentrations of 3, 6, and 14 ppm, respectively, versus the Control treatment (24 ppm). For a 62-d flock, mid-house NH₃ concentrations were significantly lower in the High and Medium treatments versus the Control treatment; concentrations in the High, Medium, and Low treatments were reduced by 47%, 32%, and 20%, respectively, versus the Control treatment.

Acidifier application rate impacts on ammonia emissions from US roaster chicken houses

Due to its potential environmental and public health impacts, emissions of ammonia (NH3) as well as several other gases from US livestock farms may be regulated. Broiler houses are important sources of NH3 emissions. However, there are no emissions data from roaster (8–12 wk old broilers, ∼4 kg ea.) houses. Producers treat the litter in broiler houses with acidifiers, such as sodium bisulfate (SBS, NaHSO4) to reduce ammonia production and protect bird health. However, there is very little data on the effect of acidifiers, particularly at high application rates on ammonia emissions. The impact of different SBS application rates [High (0.95–1.46 kg m−2, whole house), Medium (0.73 kg m−2, whole house), Low (0.37–0.49 kg m−2, whole house), and Control (0.37–0.49 kg m−2, brood chamber)] on ammonia emissions was evaluated in commercial roaster houses over 22 months spanning eight flocks. Ammonia emission from each fan was measured with an acid scrubber that operated only when the fan operated. Emissions were calculated using >95% measured data with the rest being estimated using robust methods. Exhaust ammonia–N concentrations were inversely correlated with the SBS application rates. Emission rates on animal unit (AU, where 1 AU = 500 kg live-mass) basis (ER, g d−1 AU−1) were reduced by 27, 13, and 5%, respectively, in the High, Medium, and Low treatments vs. the Control treatment (mean: 100 g d−1 AU−1, range: 86–114 g d−1 AU−1). Emission rates for the Control treatment measured in this study on roasters were mostly higher than ERs in the literature. Differences in ERs are not only due to diet, environmental and management conditions, but also due to measurement methods.

Use of non-thermal plasma and UV-light for removal of odour from sludge treatment

Non-thermal plasma (NTP) systems can be used for abatement of odour nuisances. Odour reductions are achieved by radical-initiated oxidation and dust collection in the plasma reactor. For some emissions a sequence of NTP followed by UV-light can improve the odour reduction further. This study was conducted to evaluate the efficiency of NTP technology combined with UV-light towards odour emissions from sludge treatment. Air from a pilot sludge dryer was treated with a pilot NTP and a UV unit. The effect of using an acid scrubber upstream the NTP system was also tested. Thermal desorption gas chromatography and mass spectrometry (TD-GC/MS) was used to analyse samples taken from the inlet and the outlet of the NTP system. The TD-GC/MS used was also equipped with a sniffing port that made it possible to record odour-active compounds eluting from the column. Relative amounts of odour-active compounds in the inlet and the outlet flow from the NTP system were compared. Bag samples from inlet and outlet were also separately analysed by an external lab and by two operators using a one-man olfactometer, a modified NasalRanger(TM). These results indicated a significant odour removal efficiency of 70-90% depending on the settings and combinations of abatement equipment.

Removal of Particulate Matter (PM10) by Air Scrubbers at Livestock Facilities: Results of an On-Farm Monitoring Program

Air scrubbers are commonly used for removal of ammonia and odor from exhaust air of animal houses in the Netherlands. In addition, air scrubbers remove a part of the particulate matter. In this article, the results of an on-farm monitoring are presented in which PM10 removal was monitored at 24 scrubbers. It was found that scrubbers with long air contact times (empty bed residence time (EBRT) > 3 s) achieved relatively high PM10 removal efficiencies (on average 79%). However, at short air contact times (EBRT < 3 s), efficiencies were lower (on average 49%). As dust particles travel through the humid scrubber environment, they grow in size and mass, which increases their chance of being intercepted and removed from the air. The results suggest that the maximum particle size is reached within this period of 3 s, but a controlled experimental setup is required to prove this assumption. Possible formation of salt aerosols inside the scrubbers may have affected measured removal efficiencies, especially for acid scrubbers, that are operated at EBRT < 3 s. As multi-stage scrubbers have a higher average air residence time, they show a higher PM10 removal efficiency than acid scrubbers and bioscrubbers. In addition, it is suggested that the gravimetric PM10 determination method might need to be improved to eliminate the effect of differences in moisture levels between scrubber inlet and outlet air on particle cutoff.