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PHYSICAL AND CHEMICAL PRINCIPLES OF ACTION OF REVERSE OSMOSIS MEMBRANE FOULING INHIBITORS AND METHODS OF OPTIMAL USAGE THEREOF

Е. Orestov, Т. Mitchenko

National technical university of Ukraine “KPI”, Kyiv, Ukraine

e-mail: e.orestov@gmail.com 

The article provides an overview of the two major classes of modern inhibitors of reverse osmosis membrane element fouling used in water treatment processes, namely the phosphonate compounds and polymer acrylic acid derivatives with different functional groups. The brief characteristics of different types of fouling — colloidal, organic, inorganic and biofouling are given. Special attention is paid to physical and chemical principles of the formation of crystals of sparingly soluble salts from supersaturated solutions and the deposition of these crystals on the surface of the membrane (the phenomenon of scaling), and the factors that affect the scaling. The main mechanisms of action of inhibitors of various classes — threshold effect, effect of deformation and effect of dispersion are described. Physical and chemical factors that determine the effectiveness of the threshold effect inhibitors are analyzed. A list of the main representatives of phosphonate and polymeric reagents, range and principle of action, advantages and disadvantages of each are given, and main modern commercial antiscalants produced with the use of these reagents are mentioned. The information on the forms and methods of application of modern antiscalant reagents is given with focus on use of different filter materials, primarily ion exchange resins, as carriers of antiscalant chemicals.

Keywords: fouling, threshold effect, phosphonates, polyacrylates, reverse osmosis.

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19.07.2013 at 4:12 pm

EXPERIENCE OF THE APPLICATION OF ISD IN ORDER TO INCREASE CAPACITY OF THE TWO-STAGE REVERSE OSMOSIS PLANT

P. Stender1, V. Polyakov1, P. Kozlov1, T. Odinokih2

1 –  SPC “ Ecosoft”, 2- PC “Concern Stirol”, Ukraine

e-mail: pstender@voda.com.ua

Theoretical and practical aspects application of internally staged design (ISD) application are considered. ISD is based on the usage of the different types of membrane elements in one pressure vessel when designing of the multi-stage reverse osmosis plants. The experience of such an approach when replacing of 144 elements in the actual RO plant is described. Several designs based on use of various combinations of the RO elements where carried out.

Described experience acknowledges an efficiency of the ISD approach. Significant increase of double-stage RO plant’s capacity and operational costs savings are proven in practice on the stipulation of acceptable  permeate quality.

Key words: reverse osmosis, membrane elements, internally staged design (ISD), permeate, selectivity.

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28.09.2010 at 12:57 pm