•Current and emerging technologies to remove calcium and magnesium ions are discussed.•A technology assessment to compare scale control technologies was conducted.•The energy consumption is the main challenge in technologies of scale control. Calcium and magnesium ions are the major components of scaling in different water sources, especially seawater. Calcium and magnesium scale causes problems in various industrial operations such as reverse osmosis unit, heating unit of multi-stage flash distillation, concentration operation of copper-molybdenum mining industry, cooling water system of power generation industry, and water injection operation of oil and gas production. In general terms, scaling affects the operation performance that leads to increased production, as well as maintenance costs. The pH control, scale inhibitors, and nanofiltration membrane have been implemented by industrial operations to control scale. However, the drawbacks of these technologies may force to seek alternative technologies which could be potential alternatives for scale control. This paper discusses the problems of calcium and magnesium scale affecting various industrial operations when seawater is used. It presents current technologies for scale control such as pH control, scale inhibitors, and nanofiltration. Moreover, the technology assessment (TA) was made to evaluate existing and emerging scale control approaches in the case of reverse osmosis (RO) process. The identification of the emerging technologies of scale control has been performed using bibliometric analysis. The comparison of the technologies was made using House of Quality (HOQ) matrix. The identified emerging technologies are: bioelectrochemical system, biomineralization, biosorbent, microbial desalination cells, step by step deposition and extraction technique, carbon dioxide as a precipitator, gas hydrate, ultrasonic crystallization, and capacitive deionization. The comparison of the technologies has shown that nanofiltration, as a common technology, could be an appropriate approach to ensure feasibility and efficiency of RO process, while emerging technology, microbial desalination cells, could become a potential alternative in the future.