Kajian ini mengenai keupayaan membran sulingan secara langsung untul memisahkan kalsium karbonat untuk pelembutan air. Parameter yang dikaji termasuk kepekatan larutan, suhu larutan dan kadar aliran larutan. Kepekatan larutan dimanipulasi daripada 0.1g/L CaCO3 ke 9.0g/L CaCO3. Hasil kajian menunjukkan fluks telap berkurang apabila kepekatan larutan bertambah. Semakin tinggi kepekatan larutan membawa kepada pemendapan zarah pada permukaan membran menyebabkan ‘fouling’, langsung mengurangkan fluks telap. Suhu larutan dan kadar aliran dimanipulasi daripada 60°C ke 80°C dan 18.92L/jam ke 27.85L/jam. Fluks telap meningkat secara linear dengan peningkatan suhu larutan dan kadar aliran larutan. Membran sulingan secara langsung merupakan proses dorongan haba. Oleh sebab demikian, peningkatan suhu larutan akan meningkatkan tenaga dorongan untuk wap air melepasi membran. Peningkatan kadar aliran larutan akan mengurankan sempadan suhu didalam proses membran sulingan secara langsung dan meningkatkan proses pengasingan. Fenomena ‘fouling’ didapati apabila 9.0g/L larutan CaCO3 menjalani proses selama 8jam. Fluks telap didapati mula menurun selepas 6 jam proses dijalankan. Pemendapan zarah pada permukaan membran kelihatan membuktikan fenomena ‘fouling’ terjadi.
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This research studied in the performance of direct contact membrane distillation in removing calcium carbonate solution or water softening. The important parameter investigated include feed concentration, feed temperature and feed flowrate. The feed concentration are vary from 0.1g/L CaCO3 to 9.0g/L CaCO3. The result indicated that permeate flux decrease as the feed concentration increase. The higher feed concentration lead to deposition of solute on the membrane surface and cause fouling, thus the permeate flux decrease. The feed temperature and feed flowrate are vary from 60°C to 80°C and 18.92L/hr to 27.85L/hr respectively. The permeate flux increase linearly with increase in feed temperature and feed flowrate. DCMD is a thermal driven process, increase in feed temperature will increase the driving force for the water vapour pass through the membrane. Increase in feed flowrate will decrease the temperature boundary layer and enhance the separation process. The fouling phenomena was observed when the 9.0g/L CaCO3 run for 8 hour. Permeate flux start to decline after 6 hours of DCMD process. The observed deposition of the solute on the membrane surface prove that fouling phenomena did occur via cake deposition before wetting and pore blocking after wetting taken placed.
Calcium carbonate removal via direct contact membrane distillation / Mohamad Fikri Asrafa