Biodegradability of organic carbon following hydrothermal carbonization treatment

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Stellenbosch : Stellenbosch University
ENGLISH ABSTRACT: Hydrothermal carbonization (HTC) is a ‘wet pyrolysis process’ that opens up a field of potential for feedstocks such as the non-traditional renewable and abundant wet agricultural residues, and municipal wastes for char production. It reduces waste and substitutes primary fuels as a source of energy. The product, known as hydrochar, has received attention because of its potential as precursors of activated carbon in wastewater remediation, soil remediation applications, solid fuels, and other carbonaceous materials. However, persistent priority and emerging micropollutants are consistently detected in numerous wastewater treatment plants that could potentially serve as feedstock for the process- this is a cause for concern. The goal of this study was to assess the impact of HTC on organic micropollutants. The working hypothesis was that the combination of high temperature and pressure would sterilize the biomass and transform micropollutants into benign products, while any residue would be readily biodegradable. Experiments indicated that char resulting from belt press sludge carbonized at 240 (with a corresponding°C pressure of 3,3MPa) was sterile, exhibiting a high fuel ratio of 0,72 and HHV 21,40 Mj/kg. Subsequently, 4 test compounds that are; carbamazepine, chloramphenicol, methylparaben, and bisphenol-A were studied for their biodegradability following HTC. Biodegradation of the test compounds extracted from the hydrochar ranged between 84% and 100% while only methylparaben indicated complete biodegradability from the liquid phase. Results of the study prove that with optimization, the question presented by residual micropollutants persisting in the natural environment following HTC technologies can be mitigated.
AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar.
Thesis (MSc)--Stellenbosch University, 2021.
Hydrothermal carbonization (HTC), Biodegradation, Micropollutants -- Environmental aspects, Hazardous waste site remediation, Sewage sludge -- Disinfection, UCTD