Brackish Water Desalination: An Effective Pretreatment Process for Reverse Osmosis Systems

Fouling and scaling of membranes in reverse osmosis (R.O.) units presents a major impediment to the effective and efficient operation of the system. Consequently, pretreatment of the water that is destined for R.O. application is mandatory. The choice of the type of pretreatment to be used depends on the quality of the raw water which may range from conventional treatment to membrane-based pretreatment applications. The objective of the study is to investigate a process that could effectively eliminate most or possibly all of the fouling/scaling materials which could be present in polluted brackish water including suspended and dissolved solids in the form of calcium, magnesium, silica, strontium, boron, iron, and microorganisms. In this context, the use of different chemicals that will effectively induce precipitation of the various foulants/scalants such as lime (Ca(OH)₂), caustic soda (NaOH), and soda ash (Na₂CO₃) will be evaluated under different operating conditions namely pH and temperature, and the results optimized so as to arrive at an effective, efficient, and sustainable pretreatment process.