The use of powdered adsorbents for water purification has many advantages and one major drawback – lack of regeneration due to difficulty in separating powdered particles. This weakness is attempted to be broken by powdered magnetic adsorbents, in particular magnetic ion exchange resins, used to remove natural organic matter (NOM) from water. In this water treatment process, NOM removal is controlled by the adsorbent content in the reactor (adsorbent dose) and the degree of its saturation. The control over the dose and saturation is done by mutual relations between the regenerated resin stream directed to the reactor and the saturated resin stream received from the reactor. An obstacle in balancing these streams is a variable volume of the adsorbent resulting from its varied swelling, depending on the features of the solution and saturation of the adsorbent. For this reason, it was proposed to distinguish new resin dose and content categories adequate to these changes, the use of which allows full control of both streams. Thus, the reactor feed stream was associated with relative fresh resin content (RRC) and relative fresh resin dose (RRD), which indicate the volume occupied by the regenerated adsorbent in the solution of water during purification. However, the stream received from the reactor was associated with saturated resin content (SRC) and saturated resin dose (SRD), which indicate the volume occupied by saturated adsorbent in the solution of water under treatment. In turn, these two categories of contents/doses are related to the swelling degree (ηSR). Another role was assigned to the third dose category, which is absolute fresh resin dose (ARD), referring to the volume occupied by the regenerated adsorbent in the solution of demineralized water. Thanks to two key features with reference properties (demineralized water, regenerated adsorbent), ARD allows one to transfer laboratory results to practice and to compare the results of various research. The resin loss factor described by the ηLS indicator was also included in this structure.
The presented study aimed to compare the effectiveness of ultrafiltration and filtration through a sand bed during the water treatment process after the coagulation and sedimentation. The study was conducted in two flow-type water treatment systems: the reference and the test system. Both systems functioned continuously with a throughput of 1 m3/h. The research has shown that both processes ensured a very effective removal of post-coagulation suspensions, however, ultrafiltration was more effective. The filtration process allowed a slightly higher removal of organic substances as compared to ultrafiltration. The effectiveness of the removal of organic substances was determined by the biological activity of sand beds, which is not allowed in the ultrafiltration process. Besides, during the filtration process, aluminum remaining after coagulation was more effectively removed. In turn, the ultrafiltration process ensured an almost 100% effectiveness in reducing the total microorganism cell count, while the effectiveness of the filtration process was approximately half of that. In the end, the possibility of replacing the filtration process with the ultrafiltration process is determined by the costs of both processes.
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