TECHNOLOGY > REVERSE OSMOSIS

Rochem's disc module technology has created major advances in the field of REVERSE OSMOSIS and its use in the desalination and purification of seawater, brackish water and city water. The Disc Tube Module (DT) is a major advance from the plate module technology which was originally developed by the West Germany Research Centre (GkSS). The patented DT Membrane-Module is a modem design for desalination and purification of liquids. It operates effectively and economically also at increased turbidity and Silt Density Index levels for reverse osmosis. The successful development of the DT module was only made possible by a precise technical approach in developing the total RO system. ROCHEM possesses the rare capability of being both the module manufacturer and the systems manufacturer. This dual capability, plus direct contact with the end user, is of great advantage to the customer. How does a RO system work? Pressure is applied to saline water to force the pure water molecules through a semi-permeable membrane. The majority of the dissolved salts, organic material, bacteria and suspended solids are unable to physically pass through the membrane and are discharged from the system in the rejected brine. The pure water is then ready for use without further treatment. Why is the ROCHEM DT MODULE SYSTEM the best choice in RO ? Firstly, the patented fluid dynamics and construction of the disc membrane stack result in an open channel, unrestricted and fully turbulent feedwater flow system. This means that suspended solids carried in the feedwater cannot be trapped or easily settle out inside the membrane module. Most importantly it also means that the infrequent and highly successful maintenance cleaning of the membranes can be achieved using a standard inbuilt cleaning system. Secondly, ROCHEM is committed to the use of only the highest quality of components, materials and methods of design and construction to ensure for the end user 24 hours per day reliability and product water quality. Advantages of ROCHEM DT module RO System Minimizes membrane scaling and fouling. While the performance of other types of RO system can be limited by membrane scaling and fouling, the unique fluid dynamics of the plate system have resolved this problem to an easily controllable degree. Simplified pre-filtration The open channel ROCHEM RO DT modules can operate without problems on filtered sea water with a Silt Density lndex(SDI) as high as 15-20. Other module systems specify SDI limits as low as 3 which require complex filtration and chemical treatments. SDI requirements of ROCHEM DT systems can easily be provided by simple sand and cartridge filters. High recovery rates for low energy costs Up to 30% from seawater —     energy costs average only 10 kWh/m3 of pure water. Up to 75% from brackish water (TDS = 5.000 ppm) -     average 4 kWh/m3 of pure water. Up 85% from city water (TDS = 800 ppm) -     average 2 kWh/m3 of pure water.   These figures relate to standard systems so if brine energy recovery is also employed for seawater desalination energy costs can be reduced by as much as further 50%. No chemical operating costs Unlike other RO systems the ROCHEM DT module technology means that no permanent feedwater pretreatment with acid is required at sea water desalination. Long membrane life The combination of low membrane scaling and fouling, highly stable membranes and a simple and effective inbuilt cleaning system means that membrane life-expectancy is not normally limited by feedwater pollution in the Rochem system. Useful membrane life of 5 years or more has proved to be a realistic figure. Lower membrane replacement costs Spirally wound and hollow fine fiber membrane elements are life-sealed at manufacture so the complete element must be replaced at relatively high cost, but the DT module system offers the possibility of replacing individual sheets of membrane at a fraction of the cost. Easy access to all membranes Modules can easily be opened up to permit exchange or inspection of each membrane cushion. This is very difficult on other types of RO modules. High quality product water / Latest membrane technology Standard ROCHEM RO systems use the latest technology, chemically stable, thin film composite (tfc) membrane materials. In addition, the use of membranes in sheet form means that we can select and accurately control the quality of the installed membrane to ensure minimal salt passage to consistently produce high quality permeate. Fail-safe unattended operation The only moving part in the system is the pump and all operating functions are automatically controlled and failsafe. No special skills are required to operate the system. Compact and flexible modular units The truly modular design and construction of all standard ROCHEM RO units simplifies transportation and installation and enables flexible use of limited floor space.