One-Step Removal of Calcium, Magnesium, and Nickel in Desalination by Alcaligenes aquatilis via Biomineralization

In desalination, a high level of calcium (Ca) and magnesium (Mg) ions in seawater can cause scale deposition on the reverse osmosis membranes and water treatment systems. This process can significantly affect the efficiency of desalination. In addition, heavy metals in seawater affect human health. Therefore, Alcaligenes aquatilis from seawater was used to remove Ca, Mg, and nickel (Ni) by microbial-induced carbonate precipitation (MICP). The purification system was then analyzed by ionic analysis and surface characterization. This study shows that the bacteria can utilize amino acids to produce carbonate and form precipitates with a high removal rate. MICP via A. aquatilis removed 91.8%, 68.5%, and 92.2% of the initial soluble Ca, Mg, and Ni, respectively. Furthermore, A. aquatilis can remove ammonium after the MICP process under oxygen-rich conditions. Therefore, we provide interesting insight into the use of Alcaligenes (in the absence of urea) to improve the seawater quality in the process of desalination.