Bioscrubber treatment of exhaust air from intensive pig production: Case study in northern Germany at mild climate condition

Abstract

Treatment by field‐scale bioscrubber of exhaust air, including ammonia (NH3) and the greenhouse gases methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2), from 13 intensive pig production houses located in northern Germany were investigated in 2013 and 2015. NH3 removal efficiencies varied between 35 and 100% with an overall average value of 79% under the NH3 inlet fluctuations from 34 to 755 g d−1 m−3 in both 2013 and 2015. Results of the electron microscopic analyses demonstrated that the bacteria Nitrosomonas sp. and methanotrophs type I were the dominant NH3 and CH4 oxidizers, respectively. However, overall average removal efficiencies of CH4 was approximately zero, which means CH4 is hard to remove in bioscrubbers under normal operation. The pH of recirculation water in the bioscrubber varied from 6.1 to 8.1, and the bioscrubbers with low pH values (<7.0) had high NH3 removal efficiencies (>79%). Electrical conductivity was commonly used to diagnose the bioscrubbers’ performance; in the present study, electrical conductivity presented a significant linear relationship with dissolved inorganic nitrogen, which indicates the performance stability of the 13 selected bioscrubbers.

Ammonia Removal Using Biotrickling Filters: Part A: Determination of the Ionic Nitrogen Concentration of Water Using Electrical Conductivity Measurement

“…The significant difference between the relationships proposed by Melse et al (2012) and Liu et al (2017) may be due to differences in the water they analyzed, the relationship proposed by [19] being obtained for only one pig farm. Nonetheless, the slope obtained by [17] was 53% greater than the theoretical value (on the basis of the slope: i.e., 0.3 vs. 0.196) and the intercept (+5.48 mS cm −1 ) seems unrealistic. A similar finding was also reported by Van der Heyden et al [18] for a pig fattening facility located in Belgium: L −1 as the unit for ammonium and considering that ammonium concentration is balanced by nitrite and nitrate concentrations, the slope is therefore 2 × 123.75/1000 = 0.247, i.e., 26% higher than the theoretical value.…”

“…Note that typical values for ground water would be lower than 1 mS cm −1 , but higher values are possible [22,23]. Another linear regression was proposed by Liu et al [17] in a study dedicated to 13 field-scale bioscrubbers in northern Germany. These authors reported the following relationship: EC mS/cm = 3.34Σ ([NH 4…”

“…A few works have reported a relationship between the amount of nitrogen ions in the scrubbing liquid and the electrical conductivity [17][18][19][20]. According to [8], half of the ammonia absorbed in the washing liquid is oxidized while the other half remains dissolved as ammonium.…”

“…A similar finding was also reported by Van der Heyden et al [18] for a pig fattening facility located in Belgium: L −1 as the unit for ammonium and considering that ammonium concentration is balanced by nitrite and nitrate concentrations, the slope is therefore 2 × 123.75/1000 = 0.247, i.e., 26% higher than the theoretical value. Taking into account that (i) nitrite and nitrate ions were not considered in the study conducted by Lagadec et al [20]; (ii) the relationships provided by Liu et al [17] and Van der Heyden et al [18] are far from the theory, it therefore appears necessary to take new measurements for different biotrickling filters in order to confirm the relationship obtained by Melse et al [19].…”

Optimization of technological processes in animal husbandry

“…Existing microclimate systems on farms in their physical buildup do not have air purification and recuperation devices [1, 5,11,13,16,17,18,20,23].…”