Environmental impact associated with odor and gaseous emissions from animal manure is one of the challenges for communities, farmers, and regulatory agencies. Microbe-based manure additives treatments are marketed and used by farmers for mitigation of emissions. However, their performance is difficult to assess objectively. Thus, a comprehensive, practical, and low-cost treatments are still in demand. We have been advancing such treatments based on physicochemical principles. The objective of this research was to test the effect of the surficial application of a thin layer (¼"; 6.3 mm) of biochar on the mitigation of gaseous emissions from swine manure. Two types of biochar were tested: highly alkaline and porous (HAP) biochar made from corn stover and red oak (RO), both with different pH and morphology. Three 30-day trials were conducted with a layer of HAP and RO (2.0 & 1.65 kg∙m-2, respectively) applied on manure surface, and emissions of ammonia (NH3), hydrogen sulfide (H2S), greenhouse gases (GHG), and odorous volatile organic compounds (VOCs) were measured. A significant reduction of NH3 and phenol emissions was observed. In the case of H2S, CH4, CO2, N2O, and other odorous VOCs, the biochar treatment reduced the emissions during the first 1~2 weeks, followed by either no effect or even (in some cases) increase of emissions. Based on this initial lab-scale testing, biochar is promising to be an effective, practical, and economical treatment to reduce emissions from stored swine manure. However, larger-scale experiments are needed to understand how biochar properties and the dose and frequency of application can be optimized to mitigate odor and gaseous emissions from swine manure. The lessons learned can also be applicable to consider using biochar for surficial applications to mitigate gaseous emissions from other types of waste and area sources.
Mixing nanoparticles with swine manure to reduce hydrogen sulfide and ammonia emissions