4 research outputs found
Recovery of chemical energy from retentates from cascade membrane filtration of hydrothermal carbonisation effluent
Organic fraction of municipal solid waste is a type of biomass that is attractive due to its marginal cost and suitability for biogas production. The residual product of organic waste digestion is digestate, the high moisture content of which is a problem, even after mechanical dewatering, due to the significant heat requirement for drying. Hydrothermal carbonisation is a process that can potentially offer great benefits by improved mechanical dewatering and valorisation of the digestate into a better-quality solid fuel. However, such valorisation produces liquid by-product effluent rich in organic compounds. Membrane separation could be used to treat such effluent and increase the concentration of the organic compounds while at the same time facilitating the recovery of clean water in the permeate. This work presents the results of the investigation performed using polymeric membranes. The study showed that membrane separation keeps a significant fraction of organics in the retentate. Such concentration significantly increases the biomethane potential of such effluent as well as the energy that could be theoretically used for the generation of process heat using the concentrated retentate in the wet oxidation process.Web of Science284art. no. 12852
Hydrothermal Carbonisation as Treatment for Effective Moisture Removal from Digestate—Mechanical Dewatering, Flashing-Off, and Condensates’ Processing
One of the processes that can serve to valorise low-quality biomass and organic waste is
hydrothermal carbonization (HTC). It is a thermochemical process that transpires in the presence of
water and uses heat to convert wet feedstocks into hydrochar (the solid product of hydrothermal
carbonization). In the present experimental study, an improvement consisting of an increased
hydrophobic character of HTC-treated biomass is demonstrated through the presentation of enhanced
mechanical dewatering at different pressures due to HTC valorisation. As part of this work’s scope,
flashing-off of low-quality steam is additionally explored, allowing for the recovery of the physical
enthalpy of hot hydrochar slurry. The flashing-off vapours, apart from steam, contain condensable
hydrocarbons. Accordingly, a membrane system that purifies such effluent and the subsequent
recovery of chemical energy from the retentate are taken into account. Moreover, the biomethane
potential is calculated for the condensates, presenting the possibility for the chemical energy recovery
of the condensates.Web of Science1613art. no. 510