Capacitive Deionization CDI
Sea or brackish water flows between two porous electrodes made of activated carbon. When an electrical voltage is applied the ions dissolved in water are attracted to their respectively oppositely charged electrode and can be removed through electrostatic adsorption. The process is divided into two alternate cycles: the purification step and the regeneration of the electrodes.
The general advantages of the procedure are the high energy efficiency and low power consumption as well as the higher recovery of produced water.
The subsurface iron and manganese removal is an established proces for the in-situ removal of these substances in central europe. Through the precipitation of iron, anorganic arsenic compounds found in the ground water can be also removed.
The process can be summarized in following steps:
- Infiltration/injection of oxygen-enriched water to the aquifer
- Natural formation of oxidation zones for iron Fe(II) and manganese Mn(II) in the well proximity
- Adsorption of dissolved arsenic As(III) and As(V) onto oxide-matrix (iron(III)-oxides) which precipitates as iron-arsenate complex
- Treated water is obtained around the well
Major advantages hereby are the high efficiency, the low energy consumption and the chemical- and waste-free process.
Besides the experimental tests and the pilot trials in Vietnam, an assessment on sustainability for the entire modular concept will be carried out taking into account environmental, economic and social aspects to determine the limits of applicability and the assessment of potential effects.
The project also involves a study for the autonomous and decentralized operation using renewable energy (PV, Wind). This includes the assessment all required parameters for the whole process within a comprehensive study based on the meteorological weather data in Vietnam.