Simultaneous phosphorus recovery, sulfide removal, and biogas production improvement in electrochemically assisted anaerobic digestion of dairy manure

Lingkan Ding, Hongjian Lin, Carlos Zamalloa, Bo Hu

Research output: Contribution to journalArticlepeer-review

Abstract

Anaerobic digestion (AD) produces renewable biogas from organic-rich waste streams, but the resultant digestate has to be subject to further nutrient recovery processes for better valorization. In this study, an electrochemical treatment unit using stainless steel mesh electrodes was integrated with an up-flow anaerobic sludge blanket (UASB) reactor to treat liquid dairy manure for simultaneous phosphorus (P) recovery, methane production improvement, and hydrogen sulfide (H2S) removal. The 36-d batch AD trial showed that a large portion of total P and reactive P were removed from the liquid dairy manure and were recovered mainly on the cathode deposits in the form of phosphate-bearing minerals. In the continuous USAB trial with an applied voltage of 1.0 V, 65.1% of the total P in the feeding manure was removed, of which 96.7% was achieved by sludge bed accumulation and 3.3% in the cathode deposit. Increases in both biogas production rate (13.0%) and methane yield (10.9%) were observed in the electrochemically assisted UASB system as compared to the one without electrochemical treatment. The electrochemical assistance helped decrease the H2S concentration in biogas by 20.8% at an applied voltage of 0.5 V and by 50.3% at 1.0 V. This electrochemically assisted UASB system can produce more biogas with less H2S content and recover P-enriched sludge in the sludge bed and the cathode deposit.

Original languageEnglish (US)
Article number146226
JournalScience of the Total Environment
Volume777
DOIs
StatePublished - Jul 10 2021

Bibliographical note

Funding Information:
The authors greatly appreciate the funding supports from Minnesota's Discovery, Research, and InnoVation Economy (MnDRIVE).

Publisher Copyright:
© 2021 Elsevier B.V.

Keywords

  • Biofuel generation
  • Biogas upgrade
  • Electrochemical treatment
  • Nutrient recovery
  • Pollutant mitigation

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