iAgua: MIDES – In search of the sustainable revolution of desalination
English translation of article featuring MIDES on 11 March 2020 in iAgua online
When water is scarce, alternative sources of water must be found to sustain human, economic and ecological activities. These facts hinder the satisfaction of the growing demand for water and protect the ecological function of the water cycle. Therefore, alternative water sources, such as reuse of wastewater and desalination of sea or brackish water, should be evaluated. Saline water desalination is a stable source of water when available.
Today, desalination using reverse osmosis (RO) technology is the leading technology for new desalination facilities at both EDAM and EDAS, with an 80% share in the total number of desalination plants installed worldwide and an upward trend, being the reference technology. However, all desalination technologies require an energy input, requiring for the most energy-efficient technology, reverse osmosis, an electrical energy consumption of at least 3 kWh / m3. In this context, and taking into account the global energy needs and the environmental impact associated with the generation and distribution of electrical energy, it is necessary to develop innovative technological solutions to address these challenges.
The MIDES project aims to revolutionize desalination by developing a sustainable low-energy process called the Microbial Desalination Cell (MDC) as a pretreatment for RO. The integration of MDC technology with commercial OI allows the desalination of seawater with an energy consumption of less than 0.5 kWh / m3.
The microbial desalination cell is a new technology that seeks a new approach in the world of water treatment, so that the resources present in wastewater and the energy and quality needs for desalination are used in the same device, treating simultaneously the two streams, obtaining treated wastewater and drinking water.
The development of this technology is part of the European Project H2020 MIDES, which seeks the demonstration of this technology to reduce electricity consumption to less than 0.5 kWh / m3 for desalination of seawater. The project has 10 partner organizations from seven different countries working together on the development of desalination plants based on MDC technology, their use, process parameters, materials, mathematical models and, in general, the generation of knowledge about the new technology developed, its implementation with the rest of the technologies and the sustainability of the processes that make up the low-energy desalination plant.
The general objective of the MIDES Project is based on the desalination of seawater with an energy consumption of less than 0.5 kWh / m3. Simultaneously, the wastewater used as an energy source is purified, obtaining two high quality streams (purified water and drinking water) starting from two streams of a lower quality (wastewater and salt water). The MIDES solution is based on the use of MDC together with the rest of the units necessary for the conditioning of the fed streams and the post-treatment of the streams.
The technology developed in the MIDES project will be evaluated in three different places with three bioclimatic conditions and different water uses, so as to cover the possible spectrum of use of the technology in terms of water to be treated, uses of product streams and places of implantation.
The main development center is the Desalination Innovation Center (CID) that Aqualia has opened in Denia, Spain. All the technologies that include the global MIDES treatment process have been installed in this center, which includes everything from pre-treatments to post-treatments, where the first MDC pilot to be built worldwide currently operates.
As a presentation, last November and taking advantage of the implementation of the MDC pilot in Denia, the Desalination Week (25-29 Nov. 2019) was held in the Alicante town, with the celebration of a desalination school organized by IHE Delft and a Workshop on Sustainable Desalination organized by Aqualia. During these events, experts from 17 countries analyzed the most innovative approaches to generate fresh water with the least energy expenditure and impact on the environment. During the three days of the event, 25 high-level papers were presented and the first demonstration site was inaugurated, a space located in the Racons Desalination Plant.
Thanks to the activities carried out here, the desalination plant is the largest in the world with the lowest energy consumption reported so far.
Recent MIDES achievements
• Construction of two pilot plants: in recent months, two pilot plants have been built using the MDC technology developed at MIDES. These pilot plants have a maximum treatment capacity of 3.6 m3 / day of desalinated water. The first of these was installed in Denia (Alicante) in November 2019 and the second is finishing its electrical assembly and will be installed in Guía de Isora (Tenerife) in April.
• Inoculation of the Denia MDC with bioelectroactive bacteria: After start-up and abiotic tests with the MDC cell, it has been inoculated with bacteria of the Geobacter genus, bioelectroactive strains that grow on the anode of the MDC cell (microbial desalination cells or MDC, and degrade organic matter generating an electron current that is what generates the potential difference to separate ions from water.
• Validation of pretreatments with ceramic membranes: after two years of work, the use of ultrafiltration membranes of ceramic materials as pretreatment of MDC and reverse osmosis has been validated in real applications. These membranes of hydrophilic materials and high mechanical resistance allow obtaining high-quality water as a pre-treatment with low energy consumption and a useful life of the membranes of over 25 years. They have been validated working with highly complex brackish natural waters, obtaining good results both in quality and in process. This technology is confirmed as a viable alternative to conventional pretreatments and conventional polymeric ultrafiltration.
(original article in Spanish) https://www.iagua.es/noticias/aqualia/mides-busca-revolucion-sostenible-desalinizacion