An evaluation of chemical, physical and biological qualities of the inlet and outlet water of desalination plants by reverse osmosis and multistage flash processes in Qeshm Island during

Background and aim: One of the most important components of community’s health is providing clean drinking water. The aim of this study is the quality evaluation of inlet and outlet water of desalination plants in Qeshm by reverse osmosis (RO) and Multistage flash (MSF) processes and also to compare water quality of outlet from both of process with National and International standards of drinking water.

Methods: The cross-sectional descriptive study was carried out during 7 months from November 2011 to May 2012. Sampling was carried out once every two months from inlet and outlet water of desalination plants in Qeshm by RO and MSF processes. Parameters were studied included total hardness, electrical conductivity (EC), total dissolved solid (TDS), turbidity, temperature, pH, fluoride, nitrate, nitrite, chloride, sulfate and biological parameter (total coliform, fecal coliform). Finally, analytical analysis was performed by SPSS (version 16) using paired T- test.

Result: Although theresults of this study showed that total hardness and fluoride concentration in the effluent of the both of the processes (RO and MSF) were lower than desirable concentration and chloride concentration in RO process was higher than allowable concentration limit, the rest of parameters (chemical and physical) in both of processes were in the acceptable range. There was not observed any coliform contamination in the effluent from the both processes (RO and MSF).

Conclusion: Due to low fluoride and hardness concentration in the effluent of the both processes (RO and MSF), it should be compensated by adding fluoride and calcium or magnesium compounds. More importantly, the both processes have high capability in providing safe drinking water quality according to water quality standards.