Untitled

One of the largest seawater reverse osmosis (SWRO) desalination plants in the world commissioned at Addur, Kingdom of Bahrain survived the numerous obstacles that brought down the plant’s production capacity to its lowest level. The drastic production loss, ever increasing heavy chemical cleaning programs, fouling of RO membranes and subsequent replacement within a short period of commissioning mystified the desalination world and drew the attention of experts in this field. Experiments and trials were conducted to identify the problems and rectify them. Ultrafiltration membrane technology emerged as the best viable alternative and was selected to improve the quality of the feedwater thereby to restore productivity. Based on that, the rehabilitation program was implemented with major changes in the infrastructure of the pretreatment section of the plant and ultrafiltration membranes were installed and operated. Soon, it became evident that the UF needed further refinement. A number of shortfalls in the UF system affected the operation and reduced the production capacity of the plant letting the operating cost to soar high. Under ‘The Addur SWRO desalination plant rehabilitation – production improvement works’ project, a team of experts investigated the probable methods to improve the production of the plant and suggested improvements with an enhanced model of UF membranes and entirely different type of RO membranes. The trials for this project were conducted at the pilot plant level; the tests were successful and the results were hopeful. With all positive expectations, ‘the production improvement works’ would be executed soon in the coming months with the improved UF membranes and use of cellulose acetate membrane type in one RO desalination production train. This paper attempts to describe the operational and mechanical problems encountered in the plant from the commissioning period till date and analyses them in view of before and after rehabilitation and sheds light on the reasons that lead to ‘the rehabilitation – the production improvement works’. The current status of the plant also is touched upon.

Seawater reverse osmosis desalination is a rather complex process when associated with bio- fouling and material problems. It requires thorough and careful study from the constituent parameter analysis to the material selection and the process implementation. From the experiences it can be seen that SWRO at Addur has passed through a path of numerous problems and hardships. Now it is anticipated that it would stand at the brink of a successful stride. Stream lining the new UF/RO scheme is a step toward the right direction for corrections. Reverting to the conventional coagulation–flocculation pretreatment and combining them along with UF technique may prove costeffective. By the beginning of 2005, Addur SWRO plant is expected to produce 5 million gallons/d of improved water quality, which will increase when the full fledge rehabilitation programme is implemented.