Optimization modeling for the use of antiscalants in the brackish ro desalination plants

Reverse osmosis (RO) technologies present a solution for water scarcity in many parts of the world where brackish water exists. Antiscalants act as a pre-treatment water additive for the RO plants in order to protect the membranes from scaling. This paper presents field and experimental lab works to examine the effects of antiscalants on the small and medium-scale brackish RO desalination plants under real operation conations. To assess the impact of the different antiscalants, a sample of 50 RO desalination plants has been selected along the Gaza Strip, Palestine. The evaluation process was based on three steps: (i) RO plant’s operational questionnaire, (ii) water samples collection and chemical water quality analysis and (iii) built a generalised linear model for operational process optimisation based on the antiscalants’ type, dilution and dose. According to the optimization model to maximize the pollutants’ removal, the results show that in order to reach the maximum salts rejection (98%) the first type of antiscalant (polyphosphates) should be used, at 1 ppm concentration with a dilution of 2 L of antiscalant to 250 L of water. However, using the second type of antiscalant (phosphonates) with the same dose and concentration would lead to a 92% salts rejection.