The Effect of Untreated and Acidified Biochar on NH3-N Emissions from Slurry Digestate

Abstract

The development of new options to reduce ammonia (NH3) emissions during slurry manure storage is still required due to the shortcomings of the current technologies. This study aimed to identify to what extent untreated and acid-treated biochar (BC) and pure acids could reduce ammonia nitrogen (NH3-N) volatilization and increase nitrogen retention in slurry digestate. The NH3-N emissions were effectively reduced by H2SO4 and H3PO4 acids, untreated BC when applied mixed into the digestate and acidified BC treatments applied on the surface of the digestate. Acidification increased the specific surface area and number of O-containing surface functional groups of the BC and decreased the pH, alkalinity and the hydrophobic property. Compared to untreated BC, the ability of BC to reduce NH3-N emissions was greater when it was acidified with H2SO4 and applied to the digestate surface. The effect on digestate pH of acidified BC when applied mixed into the digestate was not different, except for H2O2, from that of the addition of the respective pure acid to digestate. The total N concentration in digestate was not significantly correlated with NH3-N emissions. These findings indicate that acidified BC could be an effective conditioner to reduce NH3-N emissions from slurry digestate storage.

Assessment of digestates prepared from maize, legumes, and their mixed culture as soil amendments: Effects on plant biomass and soil properties

“…Because the nitrogen input did not correlate with N uptake by plants ( Figure 4B ), a possible explanation for this could be the lowered losses of nitrogen: lower pH putatively mediated reduction of ammonium to non-volatile cation form, and its volatilization was further mitigated due to enhanced nitrogen transformation and mineralization activities. A study done with slurry digestate showed that NH 3 emissions were lower when it was acidified ( Covali et al., 2021 ). Decreased TN content in the M+BB variant could have been coupled with decreased nitrogen mineralization, determined by urease (Ure) activity (compared to other legume-based digestate variants); see Figure 6A .…”

Potential control of ammonia emissions from poultry droppings by using biochar with insight to its effect on growth rate and liver cytokines

“…Several studies have been concerning the use of biochar as a bio-cover or bio-mix for reducing NH3 emissions with showing variable effectiveness in reducing emissions showing that the efficiency was highest in the first week and gradually reduced over the period (Miirkhanuly et al, 2020;Covali et al, 2021). However, McGuiggan et al (2022) did not show any reduction in NH3 emissions with applying biochar.…”