Search results for " Salinity Gradient"

Experimental analysis of a continuously operated reverse electrodialysis unit fed with wastewaters

2017

Reverse Electrodialysis (RED) is one of the most promising technologies to convert salinity gradient chemical energy into electricity. RED units are traditionally operated with natural streams as river water and seawater thereby limiting the spread of the technology in sites far from coastal areas. Aim of the present work is that of exploring and expanding feed possibilities for RED systems by employing waste streams. Thus, an experimental study was performed by testing, for the first time, a Reverse Electrodialysis (RED) unit fed with a high salinity wastewater originated in a fish canning factory, and a low salinity wastewater from a sewage treatment plant. Uninterrupted, long duration ex…

Reverse electrodialysis: advanced modelling and scale-up

Energetic Valorisation of Saltworks Bitterns via Reverse Electrodialysis: A Laboratory Experimental Campaign

2023

Concentrated bitterns discharged from saltworks have extremely high salinity, often up to 300 g/L, thus their direct disposal not only has a harmful effect on the environment, but also generates a depletion of a potential resource of renewable energy. Here, reverse electrodialysis (RED), an emerging electrochemical membrane process, is proposed to capture and convert the salinity gradient power (SGP) intrinsically conveyed by these bitterns also aiming at the reduction of concentrated salty water disposal. A laboratory-scale RED unit has been adopted to study the SGP potential of such brines, testing ion exchange membranes from different suppliers and under different operating conditions. M…

Thermolytic reverse electrodialysis heat engine: model development, integration and performance analysis

2019

Abstract Salinity gradient heat engines represent an innovative and promising way to convert low-grade heat into electricity by employing salinity gradient technology in a closed-loop configuration. Among the aqueous solutions which can be used as working fluid, ammonium bicarbonate-water solutions appear very promising due to their capability to decompose at low temperature. In this work, an experimentally validated model for a reverse electrodialysis heat engine fed with ammonium bicarbonate-water solutions was developed. The model consists of two validated sub-models purposely integrated, one for the reverse electrodialysis unit and the other for the stripping/absorption regeneration uni…

Effect of different aqueous solutions of pure salts and salt mixtures in reverse electrodialysis systems for closed-loop applications

2018

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…

REVERSE ELECTRODIALYSIS FOR POWER PRODUCTION FROM OILFIELD WASTEWATERS

2022

Produced waters (PWs) are wastewaters generated by crude-oil extraction processes. They can present very different characteristics depending on the field location and production process. Dispersed oil, dissolved organics and solid particles are usually the main components. Moreover, PWs can contain a very high quantity of dissolved salts 1, with a total dissolved solid (TDS) concentration up to 300 g/L. Each barrel of extracted oil requires the simultaneous extraction of 3 barrels of produced water2 on average. PWs are often discharged into the sea, or sent in evaporation ponds thus leading to a dramatic environment impact3. Reinjection in the extraction well is currently the most common an…