Effects of hydrochar derived from hydrothermal treatment of sludge and lignocellulose mixtures on soil properties, nitrogen transformation, and greenhouse gases emissions

Majid Ebrahimi; Johannes Friedl; Mohammadjavad Vahidi; David W Rowlings; Zhihui Bai; Kameron Dunn; Ian M O'Hara; Zhanying Zhang

doi:10.1016/j.chemosphere.2022.135792

Effects of hydrochar derived from hydrothermal treatment of sludge and lignocellulose mixtures on soil properties, nitrogen transformation, and greenhouse gases emissions

Chemosphere. 2022 Nov;307(Pt 2):135792. doi: 10.1016/j.chemosphere.2022.135792. Epub 2022 Jul 21.

Authors

Majid Ebrahimi¹, Johannes Friedl², Mohammadjavad Vahidi³, David W Rowlings², Zhihui Bai⁴, Kameron Dunn⁵, Ian M O'Hara⁵, Zhanying Zhang⁶

Affiliations

¹ Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, Brisbane, Queensland 4000, Australia. Electronic address: majid.ebrahimi@hdr.qut.edu.au.
² Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia; School of Biology and Environmental Science, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia.
³ Department of Soil Science, Faculty of Agriculture, University of Birjand, Birjand, Iran.
⁴ Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China.
⁵ Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, Brisbane, Queensland 4000, Australia.
⁶ Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, Brisbane, Queensland 4000, Australia. Electronic address: jan.zhang@qut.edu.au.

PMID: 35872065
DOI: 10.1016/j.chemosphere.2022.135792

Abstract

In this study, hydrochar samples derived from hydrothermal treatment (HTT) of sludge and sludge-biomass mixtures were applied to a sandy soil and their effects on soil properties, soil nutrients, greenhouse gas (GHG) emissions, and soluble heavy metals were investigated. The application of untreated sludge and hydrochar derived from HTT of sludge at 180 °C led to the highest soluble nitrate, CO₂ and N₂O emissions, followed by the application of hydrochar samples derived from HTT of sludge-biomass mixtures at 180 °C. Although the application of hydrochar samples derived from HTT of sludge alone and sludge-biomass mixtures at 240 °C in sandy soil led to the lowest emissions of CO₂ and N₂O, it resulted in lower levels of soil electrical conductivity (EC), cation exchange capacity (CEC) and soluble phosphorus. The application of hydrochar samples derived from HTT at 240 °C led to the production of CH₄ and lower nitrate-N contents than hydrochar samples derived from HTT at 180 °C. These results indicated that the soils containing hydrochar samples from HTT at 240 °C were anaerobic, which might inhibit the growth of plants. The application of hydrochar samples derived from HTT of sludge-biomass at 180 °C led to significantly improved contents of soil soluble phosphorus (2.56 and 2.84 g kg^-1 soil) and soil nitrate-N (160.2 and 263.2 mg kg^-1 soil) at the end of 60 days of incubation. However, these contents were lower than the contents of soluble phosphorus (3.71 and 4.45 g kg^-1 soil) and nitrate-N (528.3 and 583.2 mg kg^-1 soil) with the application of untreated sludge and sludge derived from HTT of sludge alone at 180 °C. Although more studies are needed to understand the mechanisms and effects on different soils, this study provides useful insights into the application of hydrochar derived from sludge-biomass mixture in soil.

Keywords: Greenhouse gases; Hydrochar; Hydrothermal; Lignocellulosic biomass; Sludge; Soil mineral nitrogen.

MeSH terms

Carbon Dioxide / analysis
Greenhouse Gases* / analysis
Lignin
Metals, Heavy*
Nitrates / analysis
Nitrogen / analysis
Nitrous Oxide / analysis
Phosphorus
Sand
Sewage
Soil

Substances

Greenhouse Gases
Metals, Heavy
Nitrates
Sand
Sewage
Soil
lignocellulose
Carbon Dioxide
Phosphorus
Lignin
Nitrous Oxide
Nitrogen