Water quality depends on remineralization’s method in the desalination plant

Abstract

<jats:p>Desalination of seawater is an alternative solution in arid zones to provide potable water. In south Morocco, the National Office of Electricity and Water (ONEE) has built many desalination factories. However, the osmosis water (permeate) is unbalanced and has a corrosive character. Therefore, a post-treatment of remineralization is necessary to return to water its calcio-carbonic equilibrium and to protect the distribution pipelines from corrosion degradation. Following the performance on limestone bed remineralization in Daoura plant in comparison with other methods, this article evaluates this technique, by checking the effect of parameters on water quality on the laboratory scale using a calcite bed pilot. We tested E.B.C.T (Empty Bed Contact Time), the upward speed, the bed length, the effect of water debit and the residence time on the treated water quality. Monitoring these parameters on the laboratory scale is indeed essential for optimal remineralization process. With the results of this study as well as economic consideration, it is possible to optimize the choice of the conditions needed for remineralization operation through limestone bed to minimize its costs with sizing and extrapolating to the industrial scale.</jats:p>

Valorization of surface-water RO brines via Assisted-Reverse Electrodialysis for minerals recovery: Performance analysis and scale-up perspectives

“…In the Daoura plant, a hardness of 5°f (in conformity with Moroccan standards) was obtained using only a calcite bed, without any prior acidification and, thus, in the absence of final NaOH injection [18]. Direct dosing of chemicals can be carried out by the addition of Ca(OH)2 and CO2 to increase both water alkalinity and hardness, which is the most common post-treatment in desalination plants, although lime is more expensive than calcite and the process consumes more CO2 [19]. Other chemicals such as Ca(OH)2+NaHCO3 or CaCl2+NaHCO3 can be adopted, though they are more expensive [17] and add large quantities of undesirable ions such as sodium and chlorides [20], whose presence can be a problem especially if the water is used for irrigation.…”

Desalinated water quality: Remineralization technique at the Al-Hoceima desalination plant (northern Morocco)

“…Indeed, remineralization using carbon dioxide (CO2) and lime in the Al-Hoceima desalination plant presents some difficulties, as the use of hydrated lime is relatively complex from a technical point of view, precisely if the permeate is hot, which reduces the solubility of the lime [21,22]. Lime is a relatively affordable and widely accessible option, but its use for remineralization presents various problems, including the risk of pipe clogging due to lime deposition on the injection equipment [23]. In addition, maintaining the optimum parameters of the water to be remineralized, such as TAC, Ca 2+ , pH, and TH, proves to be a complex task.…”