Several combinations of vessels are possible in a Deionisation system, apart from the standard Two Bed configuration. For better appreciation of the information below, it is suggested that the page titled Two Bed Deionisation is viewed first. Usually the Multi-Bed systems are custom designed for specific applications and can include the following configurations: It is necessary to obtain a detailed water analysis to help determine which Purolite Multi-Bed combination would be appropriate. Again consideration must be given to water quality desired, the operating conditions (e.g. temperature), and any other site-specific constraints before deciding on a particular configuration. The reasoning in choosing a Purolite® Multi-Bed design is generally to trade off the higher capital cost incurred in including the additional units, with the lower operating cost for overall regeneration of all the units. Incorporation of Purolite WAC and Puolite WBA resins in the design will typically reduce the overall cost of regeneration, as the efficiency of regeneration is much higher than for the Purolite SAC or Purolite SBA type of resins. In the case of a SAC - SBA - SAC system, a higher water quality can be obtained with removal of the final traces of sodium that are usually present in the effluent from the SBA unit. This can sometimes produce a water quality close to that of a Mixed-Bed system without having the complicated valving or compressed air requirement typical of such systems. For Purolite Multi-Bed applications, the following Purolite resins may be considered: Purolite® Weak Acid Cations: C104
For situations where organic loading in the water supply is considered to be high, the inclusion of an Organic Scavenging resin bed as pretreatment to the Deionization vessels may be cost effective. Purolite® Resins that are suitable for this purpose would include:
A500P
A501P
A850
A860
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