MEMBRANE DISTILLATION CRYSTALLIZATION FOR PRODUCTION OF HIGH GRADE INDUSTRIAL SALT

• Main Author: Hidayat, Bambang
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67378
• Institution: Institut Teknologi Bandung

Indonesia Ministry of Industry estimated that Indonesia needs 4.6 million tons industrial salts by 2021, while the use of local salts for industries only around 1.5 million tons. Current Industrial salt is made with evaporation and recrystallization methods which are considered to be less energy efficient. The most recent technology that can be used to produce industrial salt are nanofiltration membrane (NF) for pretreatment and a distillation-crystallization membrane (MDC). The aim of this research are to produce high garde industrial salt by using membrane technology and to determine the effect of operating conditions on the recovery and purity of salt crystals using NF and MDC membranes. This study used seawater RO brine model as feed solution which was pretreated with NF for 3 hours. Variations in the NF membrane process are differentiating the operating pressures to 3, 5, and 7 bar. Concentration of the salt solution and crystallization was carried out with MDC at a temperature of 70°C. For MDC process, aeration and adding 0.19 g NaCl as seeding were carried as operating system variations. Lastly for process using NF Product solution, final concentration of feed solution, were varied to 350 g/L NaCl and 400 g/L NaCl. The results showed that the escalate of operation pressure increases the permeate flux on the NF membrane. NF systems using 5 bar as operating pressure has the highest rejection of impurity with Ca2+ and Mg2+ rejection of 65% for both. On MDC operations, aeration increases the permeate flux, and addition of crystals significantly affects the salt crystals result. The most optimum condition to produce crystals and minimize foulant on membrane surface are adding aeration and seeding, with crystals produced 75 times higher compared to operation without aeration and seeding. Variations by concentrating the solution to the supersaturation zone, adding seeds and aeration are the most optimal conditions to produce a large amount of salt crystals, with purity of salt achieved 95.1% which exceeds the SNI standard for industrial salt.