Hydrochar and hydrochar co-compost from OFMSW digestate for soil application: 3. Toxicological evaluation

Ghanya Al-Naqeb; Viktoryia Sidarovich; Donato Scrinzi; Ilaria Mazzeo; Sergio Robbiati; Michael Pancher; Luca Fiori; Valentina Adami

doi:10.1016/j.jenvman.2022.115910

Hydrochar and hydrochar co-compost from OFMSW digestate for soil application: 3. Toxicological evaluation

J Environ Manage. 2022 Oct 15:320:115910. doi: 10.1016/j.jenvman.2022.115910. Epub 2022 Aug 7.

Authors

Ghanya Al-Naqeb¹, Viktoryia Sidarovich², Donato Scrinzi³, Ilaria Mazzeo², Sergio Robbiati², Michael Pancher², Luca Fiori⁴, Valentina Adami²

Affiliations

¹ Center Agriculture Food Environment (C3A), University of Trento, Trento, Italy; Department of Food Sciences and Nutrition, Faculty of Agriculture Food and Environment, University of Sana'a, Sana'a, Yemen. Electronic address: ghanya.alnaqeb@unitn.it.
² Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy.
³ Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy.
⁴ Center Agriculture Food Environment (C3A), University of Trento, Trento, Italy; Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy.

PMID: 35947910
DOI: 10.1016/j.jenvman.2022.115910

Abstract

Modern societies produce ever-increasing amounts of waste, e.g. organic fraction of municipal solid waste (OFMSW). According to the best available techniques, OFMSW should be treated through anaerobic digestion to recover biogas and subsequently composted. An innovative scheme is under investigation, where anaerobic digestion is combined with hydrothermal carbonization (HTC) and composting. The final product, referred to as hydrochar co-compost (HCO), is under study to be used as an unconventional soil improver/fertilizer. Recent studies showed that HCO is not phytotoxic. However, nothing is known about the toxicity of HCO on cells as part and organisms as a whole. This study aims to investigate in vitro genotoxicity and cytotoxicity of the HCO and its precursors in the production process. In particular, we tested water and methanolic extracts of HCO (WEHCO and MEHCO) from one side and methanolic extracts of hydrochar (MEH) and OFMSW digestate (MED) as well as liquor produced downstream HTC (HTCL) from the other side. Genotoxicity was investigated using cytokinesis-block micronucleus assay in Chinese Hamster Ovarian K1 (CHO-K1) cells. Cytotoxicity was tested in vitro against a panel of human cells line. Zebrafish embryo toxicity upon MEH treatment was also investigated. Results show that incubation of CHO-K1 cells with all the tested samples at different concentrations did not cause any induction of micronucleus formation compared to the vehicle-treated control. Treatment of cells with MEH, MED, HTCL and MEHCO, but not WEHCO, induced some degree of cytotoxicity and MEH showed to be more cytotoxic against tested cells compared to the MEHCO. Toxicity effect at the highest tested concentrations of MEH on zebrafish embryos resulted in coagulation, induction of pericardial edema and death. In conclusion, the hydrochar co-compost cytotoxicity is similar to standard compost cytotoxicity. Hence composting the hydrochar from OFMSW digestate is a good step to eliminate the cytotoxicity of hydrochar.

Keywords: Co-compost; Cytotoxicity; Genotoxicity; Hydrochar; Zebrafish.

MeSH terms

Anaerobiosis
Animals
Biofuels
Composting*
Humans
Refuse Disposal* / methods
Soil
Solid Waste
Zebrafish

Substances

Biofuels
Soil
Solid Waste