World’s largest immersed membrane filtration plant for potable water. In 2000, Black & Veatch (SEA) Pte Ltd (formerly Binnie Black & Veatch), commenced consulting services for the design and construction supervision of upgrading works at the major Choa Chu Kang Waterworks (CCK) in Singapore.

CCK has a treatment capacity of 364 Ml/d (96 mgd) and treats blended reservoir waters from three coastal sources. One source has particularly high levels of organic carbon and microorganisms, which in the past have challenged existing treatment works to consistently meet treated water quality standards. Black & Veatch professionals conducted pilot plant trials evaluating immersed microfiltration and ultrafiltration membranes to ascertain suitability for use in full-scale operation.

Meeting higher water quality standards. As a result of the pilot plant trials, Black & Veatch recommended the inclusion of immersed membranes to meet the more stringent water quality standards of international regulatory bodies, such as the United States Environmental Protection Agency and the World Health Organisation.

The study showed that the use of coagulant followed by immersed membranes was not able to consistently produce a treated water of suitable quality, particularly in terms of trihalomethane (THM) content. The plant’s design required the additional treatment steps of ozone and granular activated carbon (GAC) contactors. In this application, which leads to a prolonged GAC life, the GAC contactors are designed to operate in the biological mode where the activated carbon is used as a medium for the growth and sustenance of microorganisms

Minimizing maintenance and construction costs. Detailed design for the upgrading of the waterworks is now completed, and construction is scheduled to begin in April 2004. In developing the treatment plant design, Black & Veatch professionals took advantage of the site topography and proposed a siphon to draw water through the immersed membranes. The siphon would be started by vacuum pump and is thereafter gravity-driven and self-regulating. This innovative approach for such a large-scale membrane plant reduces construction costs and provides the client with a low maintenance plant.