Scale-up of a peroxide-based pig slurry additive for gaseous emission reduction and downstream value retention

Abstract

Pig slurry is an agricultural residue with potential for utilisation as organic fertiliser and biomethane feedstock. That potential value is typically diminished via greenhouse and ammonia gaseous losses during temporary storage, an issue further exacerbated by the global warming, pollutant and malodorous nature of those compounds. Existing methods of reducing emissions from pig slurry may require significant capital outlay and/or may prove difficult to retrofit. A promising reactive oxygen-based additive (GasAbate®) was thus scaled-up to 1 m³ tanks filled with 750 L weaner slurry. Several experiments were carried out in three distinct phases, namely i. ambient temperature scale-up; ii. heated 1 m³ trials to determine optimal application method; iii. heated 1 m³ trials to compare results in static and dynamic chamber scenarios, with each iteration aiming to garner understanding of treatment efficacy under various conditions. The results demonstrate the scalability of this additive, its efficacy in reducing total volume of gaseous emissions (63–90% reduction), ammonia emissions (22–58% reduction) and malodorous compound evolution (22–83% reduction for a range of compounds) during temporary storage and the resulting retention of energy and nutrient value in the slurry, with 34–57% higher biomethane potential. The use of this additive could be well suited to farms that require short-term slurry storage (ca. 30 days) before feeding the slurry to a biogas system.