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a b s t r a c tDesalination of seawater and brackish water by reverse osmosis to produce potable and process water has been widely used. But the precipitation of low soluble salts is one of the major problems in RO plants operation. Several well-known techniques are used to protect membranes and antiscalant dosing is one of the most widespread. A wide range of reliable and efficient inhibitors have been developed but the trend of the last decade is creation environmentally friendly ("green") chemicals: phosphorus-free and biodegradable. A relative ability of industrial samples of four phosphorus-free polymers (polyaspartate (PASP); polyepoxysuccinate (PESA); polyacrylic acid sodium salt (PAAS); copolymer of maleic and acrylic acid (MA/AA)) and of three phosphonates (aminotris (methylenephosphonic acid), ATMP; phosphonobutane-1,2,4-tricarboxylic acid, PBTC; and AMINAT) to inhibit carbonate membrane fouling in the simulated Black Sea water under reverse osmosis (RO) conditions for the dosages ranging from 1 to 25 ppm is tested. The following ranking ATMP > HEDP > PESA (400 ÷ 1500 Da) ~ PASP (1000 ÷ 5000 Da) > PAAS (3000-5000 Da) ~ MA-AA is found. A comparison of this ranking with that one performed following the NACE Standard TM0374-2007 under static conditions confirmed results provided by NACE Protocol.