Effect of Different Treatments on the Concentration of Chloride and Free Chlorine in Bottled Water and WASA Distributed Water in Chattogram

Abstract

After several treatment process, Chattogram Water Supply and Sewerage Authority (CWASA) distributes the water from the Karnaphuli river into the Chattogram city. In this study the supplied water by CWASA and mineral water marketed around the country were analyzed. The CWASA supplied water samples were collected from three locations of Chattogram city and three samples of bottled mineral water of different brands were collected. Each sample was replicated three times and processed though filtration, sunlight treatment, boiling, combined treatment (boiling+filtration). The results were compared with the bottled mineral water samples. Recently a newspaper claimed that CWASA is applying extra chlorine to kill the coronavirus in the Covid-19 pandemic situation. That is why the Free Chlorine, Chloride Ion, pH and TDS of the supplied water are analyzed to determine if there is any health issue regarding this matter. In the raw supply water samples, maximum mean Chloride ion was observed in the sample WASA water 03 (391.07 ppm). The maximum mean free chlorine was observed in the raw WASA water 01 (0.5 mg/L) which lies within the standard limit. The highest pH in the raw water was observed in the WASA water 02 (8.2). In the raw water the maximum TDS was observed in WASA water 01 which is about 172. Among the bottled raw mineral water highest Chloride was observed in water bottle 03 (128.55 ppm), highest pH was observed in bottled water 01 (8.14), highest TDS was observed in the bottled water sample 03. Each result was varied after different treatments. But all of them were found within the standard limit. The free chlorine concentration claimed in the news was 0.5 to 1.0 mg/L. The standard limit is 0.2 to 0.5 mg/L. The news about increasing the chlorine in water can be true but this might be used for limited time only. After the study the results were within the standard limit.