Acidification is a well-known treatment to reduce NH3 emissions from livestock slurries by lowering their pH, but its application at the farm scale is still limited. The acid dosage depends on the acid strength and slurries composition. Acidification does not have a lasting effect and after the acid addition the slurry pH tends to rise due to its buffer system. By studying 54 samples of pig slurry, dairy cattle slurry and digestate, this study aimed to: (i) identify the chemical-physical parameters related to the sulphuric acid (98% w/w) dosage necessary to reduce pH at 5.5, and pH variation over time; (ii) develop predictive models for the acid dosage and the pH after one (pH1w) and two weeks (pH2w) of storage based on slurry composition by using regression trees (RT) and random forests (RF). Acid dosage ranged between 0.8 and 11.7 ml kg−1 increasing with slurry alkalinity, with digestate requiring significantly higher dosage than slurries. Pig slurry showed significantly higher pH increase than the other two slurries. Finally, the pH trend over time was negatively correlated with the solids content. The RF identified the alkalinity and the initial slurry pH as the most important variables in explaining the required acid dosage, while for pH1w and pH2w it identified the total organic carbon and volatile solids. Based on RF results, RT models accurately predicted required acid dosage (r2 = 0.881), the pH1w (r2 = 0.728) and pH2w (r2 = 0.667). Therefore, these simple models can have practical applications for reducing NH3 emissions.

Acidification of livestock slurry and digestate to reduce NH3 emissions: Predicting needed H2SO4 dosage and pH trends over time based on their chemical-physical composition / A. Finzi, A. Heidarzadeh, E. Dinuccio, R. Ambrosini, G. Provolo. - In: BIOSYSTEMS ENGINEERING. - ISSN 1537-5129. - 240:(2024 Feb), pp. 1-13. [10.1016/j.biosystemseng.2024.02.012]

Acidification of livestock slurry and digestate to reduce NH3 emissions: Predicting needed H2SO4 dosage and pH trends over time based on their chemical-physical composition

A. Finzi
Primo
;
A. Heidarzadeh
Secondo
;
R. Ambrosini
Penultimo
;
G. Provolo
Ultimo
2024

Abstract

Acidification is a well-known treatment to reduce NH3 emissions from livestock slurries by lowering their pH, but its application at the farm scale is still limited. The acid dosage depends on the acid strength and slurries composition. Acidification does not have a lasting effect and after the acid addition the slurry pH tends to rise due to its buffer system. By studying 54 samples of pig slurry, dairy cattle slurry and digestate, this study aimed to: (i) identify the chemical-physical parameters related to the sulphuric acid (98% w/w) dosage necessary to reduce pH at 5.5, and pH variation over time; (ii) develop predictive models for the acid dosage and the pH after one (pH1w) and two weeks (pH2w) of storage based on slurry composition by using regression trees (RT) and random forests (RF). Acid dosage ranged between 0.8 and 11.7 ml kg−1 increasing with slurry alkalinity, with digestate requiring significantly higher dosage than slurries. Pig slurry showed significantly higher pH increase than the other two slurries. Finally, the pH trend over time was negatively correlated with the solids content. The RF identified the alkalinity and the initial slurry pH as the most important variables in explaining the required acid dosage, while for pH1w and pH2w it identified the total organic carbon and volatile solids. Based on RF results, RT models accurately predicted required acid dosage (r2 = 0.881), the pH1w (r2 = 0.728) and pH2w (r2 = 0.667). Therefore, these simple models can have practical applications for reducing NH3 emissions.
Cattle slurry; Pig slurry; Digestate; Sulphuric acid; Random forests; Regression trees
Settore AGR/10 - Costruzioni Rurali e Territorio Agroforestale
Settore AGR/09 - Meccanica Agraria
feb-2024
Article (author)
File in questo prodotto:
File Dimensione Formato  
Finzi 2024 - Acidification of livestock slurry and digestate.pdf

accesso riservato

Descrizione: Research Paper
Tipologia: Publisher's version/PDF
Dimensione 2.28 MB
Formato Adobe PDF
2.28 MB Adobe PDF   Visualizza/Apri   Richiedi una copia
Acidification_manuscript_clean+version.pdf

accesso aperto

Descrizione: Pre-print
Tipologia: Pre-print (manoscritto inviato all'editore)
Dimensione 1.47 MB
Formato Adobe PDF
1.47 MB Adobe PDF Visualizza/Apri
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/1035629
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? 0
social impact