Alkalinity and Hardness of Natural Waters in Chittagong City of Bangladesh

Alkalinity and hardness often used exchangeable when discussing water quality. These collective properties of water share some resemblances but are distinctly different but both has high mineral content. Generally, the water shows alkalinity due to the presence of weak acid and strong base resulting salt, typically as the form of bicarbonate salt and it can create some serious problems in water body. Hard drinking water, carry excess of Ca and Mg salt, may have moderate health benefits but can pose critical problems in domestic and industrial settings. Thus, it is important to assess the water quality with respect to hardness and alkalinity. The objectives of this study to provide an overview of alkalinity and hardness, an understanding of the importance of alkalinity and hardness from ecological perspectives and management, a summary of methods for measuring each, and the current state regulations for each in public waters of Chittagong city. The results obtained for pH, conductivity and alkaline ionic compositions from different surface and ground water samples of Chittagong city presented here with critical observations. For investigations, some related anions and metals examined by UV-visible spectrophotometer and FAAS utilizing Na-tetraborate after the pre-concentration on a column packed with Amberlite XAD-16 resin. The results show that some parameters such as salinity, total alkalinity and hardness; Na+, Ca2+, Cl–, and HCO3– loaded in both surface and ground water is quite high than slandered value; other parameters like NO3–, NO2–, SO42-, PO43-, K+, NH4+, and Mg2+ levels are in permissible range. Overall, it may state that the water of studied areas is very hard, saline as well as alkaline and suggesting that water should not uses for household, irrigation, and industrial purposes without proper treatment.