The Proof-of-the Concept of Biochar Floating Cover Influence on Swine Manure pH: Implications for Mitigation of Gaseous Emissions From Area Sources

Zhanibek Meiirkhanuly; Jacek A Koziel; Andrzej Bialowiec; Chumki Banik; Robert C Brown

doi:10.3389/fchem.2020.00656

The Proof-of-the Concept of Biochar Floating Cover Influence on Swine Manure pH: Implications for Mitigation of Gaseous Emissions From Area Sources

Front Chem. 2020 Aug 7:8:656. doi: 10.3389/fchem.2020.00656. eCollection 2020.

Authors

Zhanibek Meiirkhanuly¹, Jacek A Koziel¹, Andrzej Bialowiec^{1

2}, Chumki Banik¹, Robert C Brown³

Affiliations

¹ Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, United States.
² Faculty of Life Sciences and Technology, Wrocław University of Environmental and Life Sciences, Wrocław, Poland.
³ Bioeconomy Institute and Department of Mechanical Engineering, Iowa State University, Ames, IA, United States.

Abstract

Mitigation of potentially hazardous and malodor compounds emitted from animal waste is needed to improve the sustainability of livestock agriculture. Bacteria control the generation of these compounds and also depend on the pH of manure. Influencing swine manure pH, especially on the liquid-air interface, may lead to a reduction of emission of odorous and hazardous compounds. The objective of this experiment was to test highly alkaline and porous (HAP) modified biochar with pH = 9.2 and red oak (RO) biochar with pH = 7.5 influence on swine manure pH acquired from the outdoor storage and deep pit storage under a barn. HAP and RO biochars were topically applied on the outdoor-stored (pH = 7.55), and pit (pH = 8.00) manures and spatial pH (every 1 mm of depth) were measured on days 0, 2, and 4. Results showed that HAP biochar increased outdoor-stored manure pH on day 4, particularly within the top 10 mm of depth, where pH ranged from 7.79 to 8.90, while in the case of RO pH ranged between 7.46 and 7.66, i.e., similar to control (7.57-7.64). Both biochars decreased pit-stored manure pH within the top 10 mm of depth (in comparison with the control pH of 8.36-8.47) to 8.19-8.30 (HAP), and 8.18-8.29 (RO) on day 4. However, differences were not considerable. The reason for the insignificant effect of biochars on pit manure was likely due to its higher buffer capacity in comparison with the outdoor-stored manure.

Keywords: area sources; biochar; buffer capacity; emissions control; liquid-air interface; mass transfer; spatial and temporal pH; swine manure.