Lara Jane S. Hadlocon

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

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.

Laboratory evaluation of electrostatic spray wet scrubber to control particulate matter emissions from poultry facilities

ABSTRACT Particulate matter (PM) is a major air pollutant from animal production with significant impacts on human health and the environment. Abatement of PM emissions is imperative and effective PM control technologies are strongly needed. In this work, an electrostatic spray wet scrubber (ESWS) technology designed for removal of PM (PM10 and PM2.5) emissions from poultry facilities was evaluated under simulated laboratory conditions. Effects of primary operating parameters – including charging voltage (0–14 kV), air speed (0.5–3.5 ms−1), droplet diameter (100–300 µm), and PM concentration (1–5 mg m−3) on the PM removal performance of the ESWS – were investigated. Predictive empirical models for PM10 and PM2.5 removal efficiencies were also developed. The preliminary results showed that the ESWS technology reduced emissions of PM10 by 85–94% and PM2.5 by 85–88% with a charging voltage of 7 kV, air speed of 0.5–0.75 m s−1, and droplet diameter of 100–150 µm. The water consumption rate was approximately 2.35 L min−1, while the total power consumed was 270 W. This study demonstrates that the ESWS could be a potentially effective and feasible tool in controlling PM emissions for commercial poultry facilities.