Water Saving Device of First Stage RO Water

       Technical Domain

       This invention is a device help improve yield of purified water in the first stage RO process.

       Background

       By using extra pressure on side of high solute concentration water in the first RO process, this water saving device purifies high solute concentration water, 30% of original feed water. After purification, the solvent will be sent to a tank before RO process as part of feed water for RO process, which helps decreasing water treatment amount, reducing discharge amount of waste water, improving energy utilization rate as well as decreasing consumption of tap water.

       Details of invention

       Operational process:

       Quality improvement of feed water in the 1st RO process:

       In general, conductivity of tap water is about 300~400µs and conductivity keeps the same after treatment process before RO. However, conductivity of solvent through this device is reduced to 45~60µs. When tap water mixed with the treated solvent, whose conductivity is reduced to around 200µs, enormously improve quality of feed water for RO process. Thus, quality of water treated after RO process also gets great improvement, whose conductivity will decline 3~4µs compared with water without treated by the invented device. Moreover, quality improvement of feed water also extends service life of membrane in RO process.

       Reuse of scrapped membrane:

       After filtering certain amount of water, efficiency of membrane used in RO process will decline, causing problems such as increase of treated water conductivity, decrease of water flow and increase of differential pressure on two sides of membrane. To keep normal operation of water treatment system, membrane must be changed. Used membrane usually will be scrapped directly. In general, membrane needs be changed if its conductivity exceeds 20µs. This water saving device is composed of parallel membrane shells with scrapped membrane inside and valves at both ends. Via opening or closing valves to control quantity of working membrane and then control yield amount of treated water.

       Fully use of extra pressure:

       High pressure pump push water through membrane in RO process and then get purified water. On the side of high solute concentration water area, there is 0.7Mpa extra pressure, usually will be reduced before discharge high solute concentration water. This water saving device use the extra pressure to filter high solute concentration water, which is supposed to be discharged directly before adding water saving device, so there is no need of new power and efficiency of high pressure pump has been fully used.

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