0000000000326662
AUTHOR
Marina Micari
Combined membrane and thermal desalination processes for the treatment of ion exchange resins spent brine
Abstract The disposal of industrial wastewater effluents represents a critical environmental issue. This work focuses on the treatment of the spent brine produced by the regeneration of ion exchange resins employed for water softening. For the first time, a comprehensive techno-economic assessment and an analysis of the energy requirements of the treatment chain are carried out, via the simulation of ad hoc implemented models. The chain is composed of nanofiltration, double-stage crystallization and multi-effect distillation. The valuable product is the brine produced by the multi-effect distillation, which can be re-used for the regeneration. Therefore, the treatment chain’s economic feasi…
Towards the first proof of the concept of a Reverse ElectroDialysis - Membrane Distillation Heat Engine
Abstract The coupling of Reverse Electrodialysis with Membrane Distillation is a promising option for the conversion of waste heat into electricity. This study evaluates the performances of the integrated system under different operating conditions, employing validated model and correlations. This work provides a detailed description of the behaviour of a real RED-MD heat engine and indicates the set of inlet concentrations, velocities and equipment size which returns the highest cycle exergy efficiency. These operating conditions were selected for the pilot plant developed within the EU-funded project RED Heat to Power. For the first time, a perspective analysis was also included, consider…
Towards the implementation of circular economy in the water softening industry: A technical, economic and environmental analysis
Abstract To reduce the environmental impact of the industrial sectors, circular strategies should be implemented to purify the effluents and recover raw materials. In this context, a novel integrated methodological approach is proposed to identify the most suitable strategy to improve the sustainability of the water softening industry via the treatment and recycling of the produced wastewater. Different concentration technologies and energy supply systems are compared to find economically feasible and environmentally friendly treatment systems. The investigated chains present the same pre-treatment step (nanofiltration and crystallization) and different concentration technologies: Multi-Eff…
Techno-economic analysis of integrated processes for the treatment and valorisation of neutral coal mine effluents
Abstract The disposal of highly-concentrated neutral coal mine effluents into the environment constitutes a severe threat to the natural ecosystem. This work proposes and compares five novel treatment chains to purify the effluent and recover raw materials. The chains present different combinations of pre-treatment and concentration technologies. In all cases, the solution sent to the concentration step is concentrated up to saturation to recover water and sodium chloride. Concerning the technical performances, the treatment chains are compared in terms of total energy demand and salt recovery. Furthermore, the economic feasibility assessment is performed via a novel global parameter, i.e. …
Effect of different aqueous solutions of pure salts and salt mixtures in reverse electrodialysis systems for closed-loop applications
Abstract Reverse Electrodialysis (RED) in a closed-loop arrangement is a viable way to convert low-grade heat into electric power. The present work experimentally investigates the use of pure salt- and equimolar two salts-water solutions as feeds in a lab-scale RED unit. RED performances were analysed in terms of Open Circuit Voltage (OCV), stack resistance and corrected power density. The pure salts and the mixtures employed were chosen via a computational analysis. Effect of feed solution velocity and concentration was investigated. Results concerning the pure salt-water experiments show that NH4Cl is the most performing salt in the concentration range probed, while higher power density v…
Techno-economic assessment of multi-effect distillation process for the treatment and recycling of ion exchange resin spent brines
Abstract A treatment chain including nanofiltration, crystallization and multi-effect distillation (MED) is for the first time proposed for the treatment of an effluent produced during the regeneration of Ion Exchange resins employed for water softening. The goal is to recover the minerals and to restore the regenerant solution to be reused in the next regeneration cycle. MED is the most crucial unit of the treatment chain from an economic point of view. A techno-economic analysis on the MED unit was performed and a novel performance indicator, named Levelized Brine Cost, was introduced as a measure of the economic feasibility of the process. Different scenarios were analysed, assuming diff…
A simulation tool for ion exchange membrane crystallization of magnesium hydroxide from waste brine
Abstract Increasing attention is nowadays paid to the management and valorisation of industrial waste brines aiming also at the recovery of raw materials. Magnesium has been listed as a Critical Raw Material by EU, prompting researchers to investigate novel routes for its recovery. Within this framework, a novel Crystallizer with Ion Exchange Membrane (CrIEM), is proposed as an innovative way to recover magnesium from industrial waste brines exploiting low-cost alkaline reactants. In the present work, a novel mathematical model of the CrIEM process is proposed to provide a useful tool for its design in different working conditions. Batch and feed & bleed continuous configurations have been …
Reverse electrodialysis heat engine (REDHE)
Abstract Reverse electrodialysis (RED) is a membrane technology for the production of electricity via the “controlled mixing” of solutions at different salt concentrations, i.e., a diluted solution and a concentrated solution. The presence of ion-exchange membranes (IEMs) allows the production of renewable energy by converting the salinity gradient, which would be dissipated during a spontaneous (i.e., uncontrolled) mixing process, into an ionic current and, in a second step, into electricity at the electrodes. RED is the inverse process of the well-known electrodialysis process for salty water desalination, in which an electric field is applied at the electrodes and ionic currents are gene…
Performance Analysis of a RED-MED Salinity Gradient Heat Engine
A performance analysis of a salinity gradient heat engine (SGP-HE) is presented for the conversion of low temperature heat into power via a closed-loop Reverse Electrodialysis (RED) coupled with Multi-Effect Distillation (MED). Mathematical models for the RED and MED systems have been purposely developed in order to investigate the performance of both processes and have been then coupled to analyze the efficiency of the overall integrated system. The influence of the main operating conditions (i.e., solutions concentration and velocity) has been quantified, looking at the power density and conversion efficiency of the RED unit, MED Specific Thermal Consumption (STC) and at the overall syste…