Fly ash as stimulant for anaerobic digestion: Effect over hydrolytic stage and methane generation rate

Lorna Guerrero*, Cristopher da Silva, Andrea Barahona, Silvio Montalvo, Cesar Huiliñir, Rafael Borja, Clio Peirano, Mario Toledo, Andrea Carvajal

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Thermoelectric fly ash was used as a micronutrient source for microorganisms in the anaerobic digestion process of thermally pretreated secondary sludge. The obtained results suggested that fly ash improved CH4 generation in the conversion of volatile fatty acids into CH4 and the fly ash contributed in the particulate organic solubilization. The maximum CH4 production rate increased from 6.52 mL/L/d to 22.59 mL/L/d when fly ash was added at a dosage of 150 mg/L in biochemical methane potential tests compared with tests with no added ash. Also, the kinetic constants of the hydrolysis of particulate organic matter were obtained in both cases (with and without added ash) in batch reactors using a first-order kinetic model. In the case of no addition, the first-order kinetic parameter was 0.019±0.002/day while with ashes this value increased to 0.045±0.000/day. Therefore, the addition of fly ash improved CH4 generation and hydrolytic kinetics in different orders of magnitude.

Original languageEnglish
Pages (from-to)1384-1391
Number of pages8
JournalWater Science and Technology
Volume80
Issue number7
DOIs
StatePublished - 1 Oct 2019
Externally publishedYes

Keywords

  • Anaerobic degradation
  • Fly ash
  • Kinetics
  • Metals
  • Methane
  • Secondary sludge

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