Mitigation of Acute Ammonia Emissions With Biochar During Swine Manure Agitation Before Pump-Out: Proof-of-the-Concept

Abstract

Ammonia (NH3) emissions from animal agriculture can cause eutrophication of water ecosystems and are precursors to secondary particulate matter (PM2.5). NH3 emissions from stored swine manure represent nutrient loss affecting the fertilizing value of manure. The short-term emission bursts occur when farmers agitate manure before emptying storage and fertilizing fields. There is no proven technology to mitigate gaseous emissions during agitation, while the hazards of acute releases (e.g., H2S) are well-known. Biochar mitigates NH3 emissions from manure over the long-term. The objective of this research was to evaluate the mitigation of acute NH3 emissions during/after agitation. Two biochars, highly alkaline and porous (HAP from corn stover) and red oak (RO), were tested. The 6 and 12 mm-thick layers of biochar powder were surficial applied followed by 3 min agitation. NH3 concentrations were measured before/during/after agitation. Mitigation was assessed by comparing: (i) the maximum (peak) flux, (ii) total emission (from agitation start till NH3 concentration returned to the before-agitation), and (iii) the total emissions during agitation. The 12 mm HAP significantly (p < 0.05) reduced (i–iii) by 63, 70, and 85%, respectively. The 6 mm HAP significantly reduced (i–iii) by 76, 75, and 78%, respectively. The 12 mm RO significantly reduced (i–iii) by 9, 53, and 57%, respectively. The 6 mm RO significantly reduced (i–iii) by 61, 86, and 63%, respectively. The NH3 emission kinetics model confirmed that a 6 mm dose was just as effective as the larger dose. More research is needed to optimize and scale-up mitigating emissions and retention of nutrients in manure with biochar.

Mitigation of Acute Hydrogen Sulfide and Ammonia Emissions from Swine Manure during Three-Hour Agitation Using Pelletized Biochar

“…The experiment evaluated three scenarios with n = 3 replication during 3 h of manure agitation: (i) control, (ii) 12.5 mm ( 1 2 inch) thick surficial application to manure surface of biochar powder, and (iii) and an equivalent (in mass) dose of pelletized biochar applied to the manure surface. The previous research showed that both 12.5 mm and 6 mm thick surficial application has a similar effect in reducing emissions [26,27]. This research selected the thicker powder dose (12.5 mm) to minimize surficial coverage bias due to the pelletized biochar's corresponding dose.…”

“…The H 2 S sensor can measure up to 100 ppm, and the NH 3 sensor can measure up to 5000 ppm. All sensors were calibrated with standard gases before the experiment [26,27]. The real-time monitoring system sampled the outlet gas of the reactor continuously at 2 L•min −1 .…”

“…Biochar powder effectively mitigates emissions of H 2 S and NH 3 for both long-term (weeks to months) [21,25] and short-term (few minutes) trials [26,27]. Chen et al reported an up to 60% reduction in H 2 S emissions and 70% to 80% reduction in NH 3 emissions by surficial biochar powder application immediately before 3-min manure agitation [26,27]. Thus, synergistic effects to biochar use could be achieved for the animal-crop production system.…”

Mitigation of Acute Hydrogen Sulfide and Ammonia Emissions from Swine Manure During 3-hour Agitation Using Pelletized Biochar

“…The experiment evaluated three scenarios with n=3 replication during 3 h of manure agitation: (i) control, (ii) 12.5 mm (½ inch) thick surficial application to manure surface of biochar powder, and (iii) and an equivalent (in mass) dose of pelletized biochar applied to manure surface. The previous research showed that both 12.5 mm and 6 mm thick surficial application has a similar effect in reducing emissions (Chen et al, 2020b;Chen et al, 2020c). In this research, we selected the thicker powder dose (12.5 mm) to minimize surficial coverage bias due to pelletized biochar's corresponding dose.…”

“…Biochar powder effectively mitigates emissions of H2S and NH3 for both long-term (weeks to months) (Meiirkhanuly et al, 2020;Chen et al, 2021) and short-term (few minutes) trials (Chen et al, 2020b;Chen et al, 2020c). Chen et al reported up to 60% reduction in H2S emissions and 70 to 80% reduction in NH3 emissions by surficial biochar powder application immediately before 3-min manure agitation (Chen et al, 2020b;Chen et al, 2020c). Synergistic effects to biochar use could be achieved for the animalcrop production system.…”