Prevention of Saltwater Intrusion: A Laboratory-Scale Study on Electrokinetic Remediation
Authors :- AA Sutar, VM Rotte
Publication :- Climate Change and Water Security. Lecture Notes in Civil Engineering, vol 178. Springer.
India has 7516.6 km length of shoreline with 66 coastal districts in mainland India, 3 in Andaman and Nicobar, and 1 in Lakshadweep. In 2017, 171 million which is 14.2% of total population of the country belongs to coastal district’s population. Taking into account the growing population, industrial growth and climate change the supply of freshwater to coastal region is creating a national challenge nowadays. The surface fresh water does not meet required standards due to pollution consequently, and ground water is considered as the best option to meet expected demands. Extreme pumping of ground water causes seawater intrusion in coastal aquifers which is a major threatening challenge to the future water needs. Usually the contaminated aquifer is abandoned resulting in the loss of a precious groundwater source. Electrokinetic barrier is the best remediation technology for prevention of saltwater intrusion which allows water and some ion transport but prevents some ions reducing salt intrusion. The principal aim of this study is to provide an Electrokinetic barrier to allow saltwater flow with minimizing Na+ and Cl− ions concentration to obtain improved quality water to meet drinking and/or irrigation standards. The laboratory scale model with dimensions 360 mm × 290 mm × 180 mm has been developed for carrying out experiments with sodium chloride solution as model solution to investigate the electrokinetic migration of soluble salts under the influence of DC electric field. An electrokinetic barrier made up of electrodes array was provided in the middle part. Effect of spacing and types of electrodes on electrical conductivity, total dissolved solids, and pH of water in pumping wells on upstream and downstream of electrokinetic barrier was analyzed. These values can be related with salinity of water. The values of electrical conductivity and total dissolved solids of the samples from pumping wells in control test were higher than of electrokinetic remediation tests. Electrical conductivity and total dissolved values were observed to increase with time. However, a particular relation between the pH of sample with time was not noticed. Experiments show that the more than 60% of saltwater intrusion was carried out by electrokinetic barrier.