Full-Scale Investigation of Methane and Ammonia Mitigation by Early Single-Dose Slurry Storage Acidification

Abstract

The effects of early acidification with sulfuric acid of animal slurry in concrete storage tanks to pH 5 on methane and ammonia emissions have been investigated on two cattle and two pig slurry storage tanks in full scale. The tanks’ up- and down-wind concentrations were measured online by cavity ring-down spectroscopy (CRDS). The inverse-dispersion method (IDM), using a backward Lagrangian stochastic (bLS) model, was used to determine the emission rates. The results show that CH4 emissions after single-dose acidification of slurry tanks in the early summer were reduced by 95 ± 14% and 95% ± 6% for cattle and pig manure, respectively, compared to the emissions measured before acidification. The reductions occurred even though pH increased during the storage with and without addition of fresh slurry. After acidification, NH3 emissions were comparable to or lower than when a natural crust was present. A supplementary experiment on small-scale slurry containers was conducted to investigate the pH development when fresh slurry was added to the acidified slurry. The influence of pH development on the long-term emission dynamics of methane is discussed by comparing the large-scale and small-scale studies. The study presents the first full-scale documentation that slurry acidification is a promising technology for mitigation of methane from slurry storage.

Simple Management Changes Drastically Reduce Pig House Methane Emission in Combined Experimental and Modeling Study

“…48 Therefore, combining slurry funnels, which we here show to reduce in-house slurrymethane emission by 89%, with subsequent anaerobic digestion, a net methane reduction of ∼90% from the total manure management chain (sum of in-house and outside storage emission), is realistic. Early summer acidification with sulfuric acid was reported to reduce slurry methane emission from the storage of pig slurry by 95% 50 and is an alternative to anaerobic digestion. Ma et al 51 also reduced methane emission by >95% using low-dose acidification with 6 kg sulfuric acid m −3 slurry .…”

Effect of Covering Deep Litter Stockpiles on Methane and Ammonia Emissions Analyzed by an Inverse Dispersion Method

“…With this model, only two analyzers for the concentration measurements were needed (instead of 4 in 2020). The Picarro models G2103, G2509, and G4301 have been validated and used previously in agricultural studies (e.g., see refs , , ).…”

“…This relatively flexible method allows measuring emissions from farm-scale stockpiles continuously with high time resolution over weeks to observe patterns and effects of weather conditions (e.g., rain, temperature). The backward Lagrangian Stochastic (bLS) model , is a type of IDM commonly used for measuring emissions from agricultural sources, e.g., lagoons, , stored liquid manure, − agricultural biodigester, , and cattle feedlot. − …”