Beyond freshwater generation: Mineral extraction from seawater desalination brine and seawater greenhouse (SG) farming

Reducing the environmental impact of waste from desalination and valorization of to salt brine Desalination is becoming increasingly common in many countries where freshwater shortages occur. Worldwide freshwater production from the desalinization process is approaching ca 100 m3/d, corresponding to ca 3.3 million tone salt production as a waste. In this salt waste, there are a lot of elements that are demanded by various industrial activities. Such as Li and Mg. Salt-Mine studies the extraction of valuable elements from desalinization brine by combining frugal and sophisticated technologies. Both Li and Mg are essential for clean energy; for batteries, both elements are classified as critical elements for energy production with zero emission of CO2. The growth in Li demand is exponential while electric cars become more popular, which is why the amount of Li used is expected to increase exponentially. Similarly, Mg is a highly demanding element in clean energy technologies, including carbon capture, low-carbon cement, and next-generation batteries. Extracting Li from the sweater is challenging due to its low concentration (ca 180 µg/L). Electrochemical methods are promising but still expensive and have scale-up challenges, and they need to be improved. However, if the starting concentration of Li is 10–100 times higher, then electrochemical technology will be more economical. Here frugal technique to increase the Li concentration of seawater to 10-100 times would be an excellent complementary approach to electrochemical technology. Therefore we focused on separating and enriching both Li and Mg by frugal processes, using solar evaporation and pH manipulation by cheap basic solution.

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Salt-Mine is one of 13 projects funded under the Belmont Forum`s Collaborative Research Action on Ocean Sustainability, within the framework of the United Nations`s SDG no. 14 (Conserve and sustainably use the oceans, seas and marine resources for sustainable development).The Salt-Mine consortium brings together researchers from eight partner institutes and fourteen stakeholder partners from five countries in three continents: Norway (Norwegian Institute for Water Research-NIVA and The Norwegian University of Science & Technology-NTNU); Australia (The Commonwealth Scientific and Industrial Research Organisation-CSIRO); South Africa (Wits University and The Council for Scientific and Industrial Research (CSIR)-Durban); Kenya (Kenya Marine and Fisheries Research Institute-KMFRI and EfD at University of Nairobi) and Somalia (Pastoral and Environmental Network in the Horn of Africa-PENHA). Salt-Mine will synergise with Coast-LaB (2019-2022) project, another collaborative research action between Norway and South Africa on ocean sustainability. Norwegian researchers in Salt-Mine will contribute in seawater desalination brine valorisation studies including; 1. lab and field tests for extraction of high purity minerals from seawater brine via using both high tech (lithium-selective membrane-based) and affordable artisanal methods. 2. Studying the Environmental and socioeconomic impact of seawater desalination plant operation and discharge on the environment by comparing the environmental legislation/regulations governing SDP discharge in the five partner countries. 3. Studies to help establish the baseline ecological conditions at coastal potential SDP discharge points in Mombasa, Cape Town, Durban and Witsand (where SDPs are planned or are already in operation) so as to quantify these effects after the plants are in operation and 4. Assess and account for the impact of SDPs` energy demand, greenhouse gases and pollutant emissions and other stressors like energy demand