Studies on the Chemical Stabilisation of Digestate from Mechanically Recovered Organic Fraction of Municipal Solid Waste

Abstract

This study aims to explore an innovative approach consisting of the Fenton's process to stabilise organic wastes as an alternative to the traditional aerobic decomposition (composting). Digestate from the anaerobic digestion of the organic fraction of municipal solid wastes was taken from a mechanical-biological treatment plant and was thoroughly characterised regarding physical, chemical and biological properties. This sludge contained around 7.8 g Fe kg TS -1 , which can be beneficial to the chemical oxidation. However, the use of zero-valent iron nanoparticles or iron(II) salt revealed treatment can be improved by adding extra iron into the system. The response surface methodology determined that the best peroxidation conditions were 35.6 g H 2 O 2 kg TS -1 and 33.1 g Fe 2? kg TS -1 , while maintaining constant pH 3, L/S 5 and room temperature. The chemical treatment enhanced the stability, reducing the oxygen uptake rate from 4.63 to 2.57 g O 2 kg VS -1 h -1 . Moreover, the germination index increased from 37 to 99.9 %, which means the treatment yielded a non-phytotoxic product. The outcomes of the present study are promising and open a new pathway for the Fenton peroxidation in semi-solid processes since this fast method can be very competitive when compared with the slow composting technology.

Door-to-Door Collection of Food and Kitchen Waste in City Centers Under the Framework of Multimunicipal Waste Management Systems in Portugal: The Case Study of Aveiro

“…Recovered biowaste is then either composted or anaerobically digested. In case of anaerobic digestion the digestates are afterwards composted [3]. Even though MBT facilities exist throughout Portugal, the fact remains that currently 59 % of biodegradable municipal solid waste (MSW) is still being landfilled [4], showing the need for other measures that favor using waste as a resource.…”

Organic Matter Characterization and Phytotoxic Potential Assessment of a Solid Anaerobic Digestate Following Chemical Stabilization by an Iron-Based Fenton Reaction

“…This finding suggests that rather than inducing more oxidative conditions, a major catalytic iron concentration could have led to a “scavenging effect” of the HO · radical (eq ) with a consequent reduced efficiency of the oxidative process, as also postulated by Wu et al Interestingly, samples treated only with the Fe 2+ catalyst evidenced an increase in the recalcitrant fraction (DTG3 peak, Figure ), especially at the greatest dosage where ferrous ions could have become complexed with humic substances. In fact, at acidic pH, Fe 2+ is adsorbed onto carboxylic groups of humic fractions. , Unlike extracted humic fractions, as reported below, no differences arose in FT-IR spectra of Fenton-treated digestates with no alteration of aliphatic groups, aromatic, ketones, and quinone groups, and polysaccharides after the oxidation process, in contrast with Quina et al, though they adopted more intense oxidative conditions (i.e., H 2 O 2 > 5 g kg –1 total solid).…”

“…Nowadays, the classical Fenton reaction is considered as one of a set of advanced oxidation processes (AOPs) , and is widely used for the chemical treatment of wastewater, industrial sludge, landfill leachate, soils, and sediments, which are contaminated with biorefractory organic compounds such as phenols, dyes, pesticides, organic solvents, pharmaceuticals, domestic chemicals, etc. − Popularity and widespread applications of the Fenton oxidation process are due to the following features: (1) it works at near-ambient temperature and pressure conditions, (2) it requires cheap, relatively reactive, and easy to handle reagents, (3) it is rapid and effective, and (4) it can be easily integrated in more sophisticated chemical technologies for the treatment of a broad range of hazardous wastes, including solid agricultural matrices such as digestates from AD plants. Although few studies recently approached the chemical stabilization of the anaerobic digestate, − they primarily focused on dewaterability and changes in the chemical characteristics of treated organic wastes. Meanwhile, no attempt has been made to assess the phytotoxic potential and investigate specific changes in spectroscopic features of digestate-derived humic-like compounds, which are keys to restore the fertility level once incorporated into arable soils.…”

Detoxification of Olive Mill Wastewaters by Fenton’s Process

“…Furthermore, from this wet waste, a high organic concentrated leach is produced. In this context, the Fenton's process can be optimized to deal with these new challenges regarding both liquid and solid contaminants [72]. Funding: This research was funded by the European Union through the European Fund for Regional Development (FEDER) within the framework COMPETE2020 by the financial support of the project POCI-01-0247-FEDER-033193 (SERENA-Development of a sludge free Fenton-integrated treatment methodology for olive mill wastewaters: a water recovery).…”