Intrusion of Seawater into Drinking Water Source: Effects on Formation and Distribution of Brominated Disinfection Byproducts

The fresh water sources often contain bromide in the range of 10 500 g/L, while in the seawater, bromide concentrations were reported in the range of 65,000 - 80,000 g/L. In the Arabian Gulf water, average bromide concentration was reported as 64,000 g/L. Chlorination of bromide rich water and/or the mixture of desalinated and ground water alters the reaction pattern and brominated DBPs are increased. The increased formation of brominated DBPs can have several problems. Epidemiological studies have reported that brominated THMs in water have a stronger correlation with low weight at birth, stillbirths and defects in neural tube. Toxicological studies have characterized brominated THMs as more toxic than their chlorinated counterparts. The brominated THMs, specifically, bromodichloromethane affects trophoblasts, which produce the hormone that is necessary while pregnant. A reduction of necessary levels of the hormone may lead to several complexity at pregnancy. Understanding the implications of seawater intrusion on formation and distributions of brominated DBPs in municipal water and their effects to human is important. The proposed study will investigate the seawater intrusion effects on distribution of brominated THMs and HAAs, bromide conversion into DBPs, their risks to human and develop a point of use device to reduce human exposure and risks. Specifically, this research aims to: (i) determine THMs and HAAs through laboratory simulation using natural seawater at various proportions to the deionized water and disinfecting using chlorination under variable operational conditions; (ii) develop models to predict THMs and HAAs species under various operational conditions; (iii) predict bromide conversion at different levels of seawater intrusion; and (iv) predict human health risks at different levels of seawater intrusion and develop risk reduction strategy. (v) develop the point of use device using locally available low-cost materials and test the device to minimize DBPs exposure through water consumption. In context to Saudi Arabia, mixture of desalinated water and groundwater contains higher levels of bromide. When bromide is present, chlorine accelerates brominated DBPs formation while these DBPs have higher toxicity and several health related issues. Effects of seawater intrusion on the level of bromide in groundwater and the consequent formation and distribution of brominated DBPs might assist in better understanding of the quality of finished water. In Saudi Arabia, it is important, due to prolong stay of water in the pipelines at higher temperature, which can promote brominated DBPs formation. This project will investigate the related issues through laboratory investigations by mixing the natural seawater into the deionized water at various proportions (to achieve bromide concentrations of 25, 50, 100, 500 and 1000 g/L respectively) conducting control experiments, developing models, predicting health risk and developing a point-of-use (PoU) filtration technology. This study will assist in developing strategy to minimize risks from DBPs in drinking water. Notably, reduction of one bladder cancer can save approximately 0.8 million SAR, spent for diagnostics, hospitalization and treatment. The results will be communicated with the water supply authorities and regulatory agencies. The coastal cities and countries are likely to be benefitted from this study.