Composting Hydrochar-OFMSW Digestate Mixtures: Design of Bioreactors and Preliminary Experimental Results
Open Access
- 7 February 2021
- journal article
- research article
- Published by MDPI AG in Applied Sciences
- Vol. 11 (4), 1496
- https://doi.org/10.3390/app11041496
Abstract
An increasing number of industrial plants integrate the anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) with a subsequent composting phase. To improve the plant productivity, a fraction of OFMSW digestate can be converted into a carbonaceous material, called hydrocar (HC), through Hydrothermal Carbonization (HTC), and then composted together with the OFMSW digestate itself, to produce “hydrochar co-compost”. The aim of this paper is to present the design and assembly of batch bioreactors, built in-house to investigate the co-composting process of OFMSW digestate and its HC, and to provide some preliminary results. The OFMSW digestate from an industrial plant was carbonized at 200 °C for 3 h in a 2 L HTC reactor, to produce wet HC after filtration. The ratio of OFMSW digestate and green waste (1:1) used as bulking medium was reproduced in four bioreactors with an increasing percentage of HC substituting the OFMSW digestate (0, 25, 50, 75%). The bioreactors managed to effectively compost the solid wet biomasses in a wet environment with temperature and oxygen control, while measuring online the oxygen consumption and thus the dynamic respirometric index (DRI). The DRI24,max measured with AIR-nl solid respirometer (standardized offline measurement) started from values above 800 mg O2 kgVS−1 h−1 before composting and dropped at the end of the process to values in the range 124–340 mg O2 kgVS−1 h−1 for the four mixes, well below the recommended limit of 500 mg O2 kgVS−1 h−1 for high-quality compost stability. These offline DRI values were confirmed by the online DRI measurements. This research is part of the international C2Land Project funded by the European Institute of Innovation and Technology Climate Knowledge and Innovation Community (EIT Climate-KIC), which is greatly acknowledged.Funding Information
- H2020 European Institute of Innovation and Technology (200059)
This publication has 26 references indexed in Scilit:
- The Study of Economic and Environmental Viability of the Treatment of Organic Fraction of Municipal Solid Waste Using Monte Carlo SimulationApplied Sciences, 2020
- Application of Hydrochar, Digestate, and Synthetic Fertilizer to a Miscanthus x giganteus Crop: Implications for Biomass and Greenhouse Gas EmissionsApplied Sciences, 2020
- Hydrothermal Carbonization of Organic Waste and Biomass: A Review on Process, Reactor, and Plant ModelingWaste and Biomass Valorization, 2020
- Hydrothermal Carbonization Kinetics of Lignocellulosic Agro-Wastes: Experimental Data and ModelingEnergies, 2019
- Impact of hydrothermal carbonization conditions on the formation of hydrochars and secondary chars from the organic fraction of municipal solid wasteFuel, 2018
- Making hydrochar suitable for agricultural soil: A thermal treatment to remove organic phytotoxic compoundsJournal of Environmental Chemical Engineering, 2018
- Genotoxic and phytotoxic risk assessment of fresh and treated hydrochar from hydrothermal carbonization compared to biochar from pyrolysisEcotoxicology and Environmental Safety, 2013
- Simple Biotoxicity Tests for Evaluation of Carbonaceous Soil Additives: Establishment and Reproducibility of Four Test ProceduresJournal of Environmental Quality, 2012
- Hydrothermal carbonization of biomass: A summary and discussion of chemical mechanisms for process engineeringBiofuels, Bioproducts and Biorefining, 2010
- The use of respiration indices in the composting process: a reviewWaste Management & Research: The Journal for a Sustainable Circular Economy, 2006