Roderick Manuzon

A Prototype Acid Spray Scrubber for Absorbing Ammonia Emissions from Exhaust Fans of Animal Buildings

Mitigation of ammonia (NH3) emissions from animal production buildings has been a challenge because of the large volume of low NH3 concentration laden air being released. Among emission mitigation technologies for concentrated animal feeding operations, acid spray scrubbers have the greatest potential for adaptation to the existing large animal facilities because of their lower fan airflow reduction, ability to simultaneously remove particulate and gaseous pollutants, and viability for zero or less waste generation by recycling effluents as liquid fertilizer. A multi-stage wet scrubber prototype that can be operated with a maximum of three stages was developed and optimized for reducing NH3 emissions using simulated conditions typically encountered at an animal building exhaust. The parameters optimized for a single-stage wet scrubber include nozzle type, nozzle operating pressure, sulfuric acid concentration, spray coverage, and air retention time. The optimized single-stage wet scrubber settings can remove emissions from 60% ±1% at 5 ppmv inlet NH3 concentration (IAC) to 27% ±2% at 100 ppmv IAC at a normal exhaust superficial air velocity (SAV) of 6.6 m s -1 . A high concentration of droplets inside the contact chamber increased the rate of inter-collision between droplets, which led to high droplet coagulation and decreased surface area for gas-liquid contact. These phenomena were prevented by operating the nozzles in the higher stages co-current to the airflow and by using fewer nozzles in higher stage. The two-stage and three-stage wet scrubbers were therefore optimized by determining the least number of nozzles in each stage that provided the most effective NH3 removal. The optimized two-stage scrubber could remove NH3 emissions from 60% ±0% at 5 ppmv IAC and 35% ±1% at 100 ppmv IAC. The optimized three-stage scrubber could remove emissions from 63% ±3% at 5 ppmv IAC and 36% ±3% at 100 ppmv IAC. Airflow retention time was found to significantly affect NH3 absorption. Reducing the superficial air velocity to 3.3 m s -1 from 6.6 m s -1 , which increased the air retention time from 0.2 s to 0.4 s, improved NH3 removal efficiencies to 98% ±3% at 5 ppmv IAC and 46% ±2% at 100 ppmv IAC for the single-stage scrubber. Similarly, the performance of the two-stage scrubber at a SAV of 3.3 m s -1 improved to 77% ±0% at 20 ppmv IAC and 57% ±1% at 100 ppm IAC. Lastly, the performance of the three-stage scrubber at a SAV of 3.3 m s -1 improved to 70% ±1% at 30 ppmv IAC and 64% ±1% at 100 ppmv IAC. It was observed that the three-stage wet scrubber did not increase the overall wet scrubber performance, as predicted theoretically. Further studies are needed so that the application of these scrubber designs becomes feasible for treating air emissions from animal buildings. The wet scrubber caused an additional backpressure of 27.5 Pa, resulting in about 8% airflow reduction for a fan operating at 12.5 Pa.

Development and evaluation of a full-scale spray scrubber for ammonia recovery and production of nitrogen fertilizer at poultry facilities.

Significant ammonia emissions from animal facilities need to be controlled due to its negative impacts on human health and the environment. The use of acid spray scrubber is promising, as it simultaneously mitigates and recovers ammonia emission for fertilizer. Its low pressure drop contribution on axial fans makes it applicable on US farms. This study develops a full-scale acid spray scrubber to recover ammonia emissions from commercial poultry facilities and produce nitrogen fertilizer. The scrubber performance and economic feasibility were evaluated at a commercial poultry manure composting facility that released ammonia from exhaust fans with concentrations of 66–278 ppmv and total emission rate of 96,143 kg yr−1. The scrubber consisted of 15 spray scrubber modules, each equipped with three full-cone nozzles that used dilute sulphuric acid as the medium. Each nozzle was operated at 0.59 MPa with a droplet size of 113 μm and liquid flow rate of 1.8 L min−1. The scrubber was installed with a 1.3-m exhaust fan and field tested in four seasons. Results showed that the scrubber achieved high NH3 removal efficiencies (71–81%) and low pressure drop (<25 Pa). Estimated water and acid losses are 0.9 and 0.04 ml m−3 air treated, respectively. Power consumption rate was between 89.48 and 107.48 kWh d−1. The scrubber effluents containing 22–36% (m/v) ammonium sulphate are comparable to the commercial-grade nitrogen fertilizer. Preliminary economic analysis indicated that the break-even time is one year. This study demonstrates that acid spray scrubbers can economically and effectively recover NH3 from animal facilities for fertilizer. GRAPHICAL ABSTRACT

Variations in Air Quality of New Ohio Dairy Facilities with Natural Ventilation Systems

As dairy operations evolve towards larger, concentrated facilities, air quality on and around the dairy farms becomes a concern. Data on air quality in and around large dairy facilities are insufficient and therefore very much needed. In this study, preliminary data on air quality spatial distribution and temporal variations on two new large dairy facilities with naturally ventilated free stall barns and outside manure storage were collected. Concentration of hydrogen sulfide (H2S) and ammonia (NH3) at 12 to 14 locations on each farm were measured in three seasons using portable gas analyzers. Odor samples were collected at odor sources, upwind and downwind locations. Dust was measured using a portable dust mass concentration meter. Gas levels inside the dairy buildings at one leeward location were continuously monitored for three days in two seasons. In addition, indoor and outdoor temperature, relative humidity, and air velocity were measured to determine effects of these parameters on air quality.

Longitudinal study to evaluate the association between thermal environment and Salmonella shedding in a midwestern US swine farm

The objective of this study was to document the association between the thermal environment in the barn and Salmonella shedding in finishing pigs. For this purpose, individual fecal samples from 900 finishing pigs (8 collections per pig) were repeatedly collected from 18 cohorts (50 pigs per cohort) on 3 sites of a multi-site farrow-to-finish production system in a longitudinal study. Pen temperature and humidity were measured every 2 min during the study period. The thermal parameters of interest were: hourly average temperature, minimum and maximum temperature, hourly temperature variation, temperature humidity index (THI) and cumulative number of hours/degree above and below the thermal neutral zone at the pen level prior to fecal sampling for 6 time periods (12h, 24h, 48 h, 72 h, 1 week and 1 month). Additional potential risk factors at the individual (e.g., sex, health events), cohort (e.g., mortality, morbidity, Salmonella status of the nursery) and pen level (e.g., type of pen) were also evaluated. Multilevel logistic models using generalized linear models, with random intercepts at pig, pen and cohort levels to account for clustering (individual samples nested within pigs, pigs nested within pens, pens within cohorts) were constructed. Site (A, B, C) was considered as a fixed effect in order to control for clustering within site. The outcome variable was Salmonella fecal status of the individual sample. Cold exposure (temperatures below the thermal neutral zone) and exposure to a THI>72 were both positively associated with risk Salmonella shedding. Nursery Salmonella status was positively associated with Salmonella shedding and pig age was negatively associated with Salmonella shedding. In the multilevel intercept-only model the largest proportion of model variance was associated with the individual fecal sample (44.8%) followed by cohort (24.5%), pen (20.5%) and pig (10.2%). The present study allowed the investigation of the association of time-variant thermal factors and Salmonella shedding. Interventions that target the thermal environment may have an effect on reducing Salmonella shedding in swine and also improve pig well-being and production efficiency. Alternatively, thermal parameters may be used to identify groups of pigs at high risk for Salmonella shedding. Future studies should be performed to investigate the cost-efficacy of interventions to improve the thermal environment of swine.

Pilot-scale field study for ammonia removal from lagoon biogas using an acid wet scrubber.

The anaerobic activities in swine slurry storage and treatment generate biogas containing gaseous ammonia component which is a chemical agent that can cause adverse environmental impacts when released to the atmosphere. The aim of this pilot plant study was to remove ammonia from biogas generated in a covered lagoon, using a sulfuric acid wet scrubber. The data showed that, on average, the biogas contained 43.7 ppm of ammonia and its concentration was found to be exponentially related to the air temperature inside the lagoon. When the air temperature rose to 35°C and the biogas ammonia concentration reached 90 ppm, the mass transfer of ammonia/ammonium from the deeper liquid body to the interface between the air and liquid became a limiting factor. The biogas velocity was critical in affecting ammonia removal efficiency of the wet scrubber. A biogas flow velocity of 8 to 12 mm s−1 was recommended to achieve a removal efficiency of greater than 60%. Stepwise regression revealed that the biogas velocity and air temperature, not the inlet ammonia concentration in biogas, affected the ammonia removal efficiency. Overall, when 73 g L−1 (or 0.75 M) sulfuric acid solution was used as the scrubber solution, removal efficiencies varied from 0% to 100% with an average of 55% over a 40‐d measurement period. Mass balance calculation based on ammonium–nitrogen concentration in final scrubber liquid showed that about 21.3 g of ammonia was collected from a total volume of 1169 m3 of biogas, while the scrubber solution should still maintain its ammonia absorbing ability until its concentration reaches up to 1 M. These results showed promising use of sulfuric acid wet scrubber for ammonia removal in the digester biogas.

Ammonia Emissions from a Commercial Poultry Manure Composting Facility

Composting is an effective waste management technology for converting animal wastes into valuable organic fertilizer. However, air emissions from composting, especially ammonia (NH3) emission, reduces the nitrogen fertilizer value of the compost and greatly impacts the environment. Ammonia emission from commercial composting facilities is not well understood and is limiting mitigation or recovery of NH3 emission from these facilities. The goal of this study was to determine the NH3 emission from a poultry manure compost facility and its temporal variations for development of mitigation strategies. A commercial composting facility was chosen for this study. Manure was supplied from four adjacent manure-belt layer barns. The composting building was tunnel ventilated by four 122-cm exhaust fans. Ammonia concentration at the building inlet and the fan exhausts was monitored quasi-continuously for one month in each of the four seasons using a MSA photoacoustic NH3 analyzer. Air temperature and humidity at the exhausts were monitored using a HOBO temperature and RH sensor and data logger. The exhaust fans were calibrated using FANS units to quantify the ventilation rate of the building. Ammonia emission rate was calculated according to the NH3 concentrations and building ventilation rate. The daily average NH3 concentrations at the exhaust of the compost house varied from 123 ppm in spring to 167 ppm in summer. The daily average NH3 emission rates of the compost facility varied from 231 kg/d in spring to 315 kg/d in summer. Strong diurnal variations exist in spring and summer seasons. Daytime NH3 emission is significantly higher than that of nighttime. The annual NH3 emission rate of the composting facility was estimated as 96,143 kg. The emission factors were calculated as 13±1.3 kg/ton·d and 0.32 ±0.14 g/d·hen. The results of this study will contribute to the development of NH3 emission mitigation technologies and management practices.

Temporal Variations in Gas and Odor Emissions from a Dairy Manure Storage Pond

As dairy production evolves towards larger and more concentrated operations, air and water quality on and around dairy farms is becoming a significant concern. It is necessary to understand air emission temporal variations for development and implementation of effective abatement technologies and management practices. The objectives of this study were to understand temporal variations in H2S, NH3, and odor emissions from a dairy manure storage pond, the effects of manure characteristics and environmental conditions on gas emissions, and gas management need of dairy manure storage ponds. One representative Ohio dairy farm with a 675-cow free-stall barn and one outside earthen manure storage pond was selected as the experimental farm. Monthly measurements of H2S, ammonia, and odor emissions from the dairy manure storage pond were conducted using a convective flux chamber and gas analyzers. Surface manure was sampled for manure characteristics analysis. Manure temperature and weather conditions were measured. The data was analyzed using general statistical description, correlation, and regression analysis.

Estimation of Ammonia Emission from Manure Belt Poultry Layer Houses Using an Alternative Mass-Balance Method

Ammonia (NH3) emission from animal feeding operations (AFOs) has caused concerns on public health and environmental degradation, such as ecosystem acidification, eutrophication, and formation of PM2.5 fine particles. Current ammonia emission measurement methodologies are accurate and reliable, but time consuming, expensive, and impractical for most facilities. In the present study, an alternative and cost effective mass balance methodology was developed to predict the ammonia emission from animal facilities. The mass balance equations have been developed to eliminate needs for tracking manure flow rate to obtain accurate NH3 estimation. The methodology was applied to three manure-belt layer poultry houses with approximately 150,000 birds in each house in Ohio and validated using continuous ammonia emission measurement data. Feed, manure and egg samples were collected from the three houses in three seasons (cold, mild, and hot) to evaluate the seasonal variation of ammonia emission from the poultry facilities. Results show that this alternative mass balance method can estimate NH3 emission from manure-belt poultry layer house effectively. NH3 emission rate from manure belt poultry layer houses with manure removal every 3.5 to 5 days was 0.07-0.37 g NH3 bird-1day-1. These results agrees well with the NH3 emission values published in the previous literatures (0.027-0.616 g NH3 bird-1day-1), but were lower than the NH3 emission rate (0.1-0.86 g NH3 bird-1day-1) measured using continuous monitoring system. In the comparison analysis of NH3 measurement and estimation emissions, Normalized Mean Error (NME), Normalized Mean Square Error (NMSE) and Fractional Bias (FB) are calculated to be 52.05%, 85.32% and -70.36% respectively. This study suggests that manure removal time interval and air temperature can be important factors impacting NH3 emission. This mass balance method can only estimate total nitrogen loss in a whole production process, which is an upper bound of NH3-N loss. It is needed to quantify other nitrogen compound gas emissions, such as N2O, NOx, N2 for accurate NH3 emission estimation.