Desalination

OBJECTIVES

The Water Technologies Department has the following objectives in the field of desalination:
1. Identify, develop and adapt technically sound and economically feasible desalination technologies, including hybrid and integrated technologies.
2. Develop and adapt non-conventional advanced feed water pretreatment technologies for seawater desalination plants.
3. Improve process performance and utilization of existing MSF plants with possibility of lowering production cost.
4. Establish reference technical standards for water desalination.
5. Carry out studies to determine costs of water desalination using existing technologies or using other newly promising technologies under prevalent conditions in Kuwait.

WATER FROM THE SEA

KISR has invested heavily in developing seawater desalination technology and became an internationally recognized center in this field. The research has focused on reverse osmosis (RO) technology due to the high potentials it provides in terms of cost and flexible capacity. The research in this area addressed four major aspects related to the development and implementation of RO technology under the prevalent conditions in Kuwait. It evaluated the pretreatment of the seawater feed, commercially available RO membranes and their methods of cleaning, alternative materials of construction for seawater RO plants, and assessed the optimum hybridization of this technology with other commercially available seawater desalination technologies.

MEMBRANE DESALINATION

Following the development of RO technology and proving its efficiency in seawater desalination, KISR focused its efforts on reducing its operational costs. The objectives were: to develop an operationally automated system, provision of alternatives for pretreatment and reduction of energy consumption through energy recovery.

Critical parameters affecting the availability and productivity of a fully automated RO unit were identified and utilized in the design and construction of a fully automated system capable of diagnosing any malfunction in equipment or changes in the quality of the feedwater. The system was running successfully without being attended to, and led to an increase in the availability of the unit by 8%.The manpower was reduced to 50% of the usual RO plant requirements. This study translates into a substantial reduction in the cost of desalinated water.

Research studies were also directed to evaluate the technical and economic feasibility of using a micro filtration system as an alternative pretreatment method for the seawater feed for RO. The study revealed that micro filtration is more viable than conventional pretreatment, both technically and economically. It showed that this technique produces feed that is comparable with beach well seawater feed and more feasible for treatment of large quantities of seawater. Further cost reduction in the water desalination was also achieved when this technology was adopted. It was estimated that the use of micro filtration could result in more than 50% reduction in the pretreatment cost of RO.

An innovative design for a very efficient energy recovery system for seawater RO plants was developed and successfully evaluated at the Doha Water Desalination Plant in Kuwait. The prototype proved its efficiency and feasibility for energy recovery systems in reducing the power consumption of the RO desalination plant and consequently reducing the cost of the product water. A patent file was prepared and submitted for registration.

The suitability of the seawater quality at the Subiya and Az-Zour sites was evaluated for future installation of RO plants. The study specified technical design criteria for future RO pretreatment systems at the two sites.

Research efforts in this area also included assessment of the feasibility of utilizing Nano-filtration (NF) technology, which is known for its ability of selective ions separation. The research focused on the potential for using NF membranes to treat sea water feed to RO or distillation plants for reducing the concentrations of Ca⁺⁺, Mg⁺⁺, HCO ^(-3) and SO₄ ^--. Reducing the concentration of these ions in the seawater feed effectively minimizes the scale-formation potential on operating surfaces, and, hence, increases desalination plants productivity and reduces operating costs.

THERMAL DESALINATION

New technologies related to thermal desalination and hybridization of processes are gradually being introduced. MSF distillation is a well established technology with proven reliability.

Hybridization between MSF and RO processes is starting to take shape. Studies are presently being conducted to evaluate new schemes for integrating MSF with other processes. The main objective of these studies is to introduce and develop new thermal desalination technologies capable of reliably producing desalinated water at significantly lower costs, compared to the existing conventional MSF process.