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230 10. COMPARISON OF GRANULAR MEDIA AND MEMBRANE PRETREATMENT
membrane pretreatment cannot be easily accounted for in an actual costebenefit analysis for full- scale desalination projects. As indicated previously, practical experience at desalination plants with open intakes and frequent algal bloom events shows the opposite trenddRO membranes downstream of UF or MF pretreatment systems are actually cleaned more frequently than these downstream of gravity granular media filtration systems due to the negative impact of the pres- surization of the source water on the algal cells contained in itdalgal cell breakage and release of easily biodegradable cell substances that accelerate RO membrane fouling.
10.9 COMMODITIZATION
Granular media filtration systems are fully commoditized and the same quality of filtra- tion media can be obtained by a number of manufacturers at a competitive market price. For comparison, membrane pretreatment systems are not commoditizeddall UF and MF membrane manufacturers offer their own design, size, and configuration of membrane ele- ments/modules, and pretreatment system racks. The membrane pretreatment systems also differ by the type, concentration, and volume of membrane cleaning chemicals needed for CEB and CIP, by filter backwash rate, type, and sequence, and by their membrane integrity testing method.
The absence of product uniformity and commoditization in the membrane market at pre- sent is an indication of the fact that membrane filtration is a fast-growing field of the water equipment industry and carries some benefits and disadvantages. The availability of multiple membrane suppliers and systems allows to better accommodate the site-specific needs of a given membrane application, thereby increasing the potential for use of membrane source water pretreatment. In addition, the lack of commoditization of the MF and UF membrane market along with the increase in membrane applications in recent years, spurs the interest of many manufacturers, which traditionally do not produce membranes to enter the mem- brane market with new products. This, in turn, results in increased competition and in accel- erated development of new membrane technologies, products, and equipment.
Fifteen years ago, there were less than half-a-dozen of membrane manufacturers, which offered MF and UF membranes and membrane systems to the municipal market and to the desalination industry. This number has increased dramatically over the past 5 years and today practically all large and many medium-size equipment and plastics manufacturers offer their own unique MF or UF membrane system.
The absence of standardization of membrane size, vessels, and configuration, however, also has a number of disadvantages that may hinder the use of membrane pretreatment, espe- cially for large desalination plants. As the membrane market gets oversaturated with manu- facturers offering similar membrane products, the market growth is likely to exceed the demand, which would trigger the exit of some of the current membrane manufacturers form the market. As a result, the manufacturers exciting the membrane market would no longer produce membrane elements and provide maintenance and technical support for their existing systems. Because their system configuration, membrane elements, and vessel type are unique, the owners of such membrane systems will have to invest significant funds and efforts to modify their membrane installations to accommodate alternative membrane equipment.