Stabilization of solid digestate and nitrogen removal from mature leachate in landfill simulation bioreactors packed with aged refuse

Wei Peng; Alberto Pivato; Francesco Garbo; Tianfeng Wang

doi:10.1016/j.jenvman.2018.12.007

Stabilization of solid digestate and nitrogen removal from mature leachate in landfill simulation bioreactors packed with aged refuse

J Environ Manage. 2019 Feb 15:232:957-963. doi: 10.1016/j.jenvman.2018.12.007. Epub 2018 Dec 11.

Authors

Wei Peng¹, Alberto Pivato², Francesco Garbo¹, Tianfeng Wang³

Affiliations

¹ DII - Department of Industrial Engineering, University of Padova, Via Marzolo 9, 35131, Padova, Italy.
² ICEA - Department of Civil, Environmental and Architectural Engineering, University of Padova, Via Marzolo 9, 35131, Padova, Italy. Electronic address: alberto.pivato@unipd.it.
³ ICEA - Department of Civil, Environmental and Architectural Engineering, University of Padova, Via Marzolo 9, 35131, Padova, Italy; School of Chemistry and Environmental Engineering, Jiujiang University, 332005, Jiujiang, PR China.

PMID: 33395764
DOI: 10.1016/j.jenvman.2018.12.007

Abstract

Digestate from biogas plants managing municipal solid waste needs to be stabilized prior to final utilization or disposal. Based on the concept of urban mining, aged refuse from a closed landfill was used to treat landfill leachate, but nitrogen removal by biological denitrification was limited. The aim of this study was to use a digestate layer in bioreactors containing aged refuse to enhance the biological denitrification capacity of the aged refuse, stabilize digestate, and mitigate the ammonia emissions from digestate leaching with leachate recirculation. Six identical landfill columns filled with 0% (R0), 5% (R5), and 15% (R15) of solid digestate above aged refuse (ratios based on Total Solids) were setup and nitrified leachate was periodically fed and recirculated to the columns. The nitrate removal rate in R5 and R15 was 3.4 and 10 times higher relative to the control (no digestate added). A 31.5-35.9% increase of solid digestate biostability was confirmed by tests performed under both aerobic and anaerobic conditions. The results showed that instead of land use, the solid fraction of digestate could be utilized as an inexpensive functional layer embedded in an old landfill site to enhance the denitrification capacity and achieve digestate stabilization with minimal ammonia leaching from digestate.

Keywords: Aged refuse; Circular economy; Landfill leachate; Nitrogen removal; Organic fraction of municipal solid waste; Solid digestate.