Impact of brewery residues spent yeast and diatomite sludge on NH3-, CH4-, H2S-, CO2-, and N2O-emissions from manure slurry

Agriculture is a leading source of ammonia emissions in many countries, primarily due to the natural release of ammonia from manure during storage and field application. Effective strategies for reducing these emissions are critical to meeting the European Union's emission reduction targets. This study investigates the potential of brewery residues—spent yeast (SY) and brewery spent diatomite sludge (BSDS)—as additives for manure treatment. Firstly, the optimal concentrations of additives was evaluated by monitoring the nitrogen household for 30 days in manure when adding 0–25 % SY or BSDS. Afterwards, pH development and emission of greenhouse and ecosystem relevant gases were monitored for manure treated with 10 % SY or 10 % BSDS for 2.5 and 6 weeks, respectively. Addition of 10 % BSDS to cattle manure slightly reduced the pH (from 7.3 to 7.1), and marginally lowers total Kjeldahl nitrogen, without significantly affecting emissions. Higher concentrations of BSDS further reduce total Kjeldahl nitrogen. High concentrations of SY promote the formation of ammonium nitrogen, yet 10 % SY addition reduced ammonia emissions considerably (from 30 mg/h to 16 mg/h). Both effects are attributed to the pH lowering action of SY. A 10 % addition of SY is sufficient to reduce pH from 7.3 to 6.8, which also slightly affects methane emissions. However, SY promotes the formation of hydrogen sulfide, likely due to leftover sulfur compounds from the brewing process, limiting its standalone applicability for emission reduction. • Spent yeast (SY) effectively reduces the pH of manure slurry. • SY addition reduces ammonia emissions by 46 %, yet lead to release of H 2 S. • SY promotes formation of ammonium nitrogen in solution. • Brewery spent diatomite sludge (BSDS) promotes loss of total Kjeldahl nitrogen. • BSDS only slightly affects greenhouse gas emission from manure slurry.