The role of desalination in removal of the chemical, physical and biological parameters of drinking water (a case study of Birjand City, Iran)

Abstract

One of the important components of public health is providing clean water in communities. According to documentations by international organizations, it is clear that high percentage of illnesses is directly related to water consumption in the society. Considering the fact that large mineral content in water can cause problems for consumers, the use of desalination to remove the minerals solute would therefore be a great idea in Iran. This cross-sectional descriptive study was performed to evaluate the role of six desalination devices (reverse osmosis) in Birjand that can remove chemical and physical parameter inputs such as nitrate, nitrite, total hardness, electrical conductivity (EC), chromium(VI), manganese, total dissolved solids (TDS), and microbial parameters (fecal coliform and total coliform) of water. One hundred and forty-four (144) samples of input and output point’s desalination were harvested and analyzed according to standard methods. The results showed that these devices could remove up to 90% chromium(VI), TDS, salinity, nitrite, from input water and 100% in many cases. The concentrations of chemical parameters in treated water were as follows: TDS = 262–369 mg/l, total hardness = 92–200 mg/l as CaCO3, nitrate = 4.31–11 mg/l, nitrite = 0 mg/l, Cr = 0–0.002 mg/l, Ca = 6.4–12.8 mg/l, Mg = 17.3–40.3 mg/l, Mn = 0 mg/l, salinity = 63 mg/l, pH range = 7–7.6, fecal coliform = 0 (MPN/100), total coliform = 0 (MPN/100), EC = 403.4–507.7 μs/cm and membrane flux retention coefficient = 1. Analysis of input and output data using paired t-test showed significant differences in these parameters (p < 0.05). Thus to remove high levels of mineral from drinking water in Birjand and since heavy metal chromium(VI) in the resource water in that area is higher than the standard requirement, using these systems can achieve good results.