P. D. Nemade et al., International Journal of Emerging Trends in Engineering Research, 9(11), November 2021, 1413 – 1417 1413 ABSTRACT In the present study laboratory studies are carried out to examine the removal of hardness by electrocoagulation process from drinking water using iron rod electrodes in batch mode. The purpose of this study was to investigate the efficiency of EC process in removal of water hardness through iron-rod electrodes in varying conditions. Experimental water sample was taken from water distribution network of local area Pune City, Maharashtra state, India. The indices for calcium and total hardness removal in pH (4.0, 7.0, and 10.0), electrical potential of 12 and 24 V and reaction times of 5 minutes to 30 minutes were measured. The maximum efficiency of hardness removal which was obtained at pH 10.0, voltage of 12 and reaction time of 60 min are equal to 98.5% and 97.5% for calcium and total hardness, respectively. Final pH of remained solution has also increased which rises with acidic pH and decreases in alcoholic pH, so the results demonstrate the direct effect of pH, potential difference and reaction time on hardness removal using EC process. Key words: Electrocoagulation, Hardness removal, Iron electrodes, Reaction time 1. INTRODUCTION Water is elixir of life and available for human consumption limited and likewise, available drinking water has been reduced because of the pollution created naturally and due to anthropogenic activities. Amongst water quality parameters, hardness is generated due to carbonates of calcium, magnesium and in lower traces; aluminum, iron and other bivalent and trivalent. Furthermore, water hardness is a vital parameter in industrial water consumption in manufacturing of high-quality products [1]. Hard water causes many problems in domestic and industrial consumptions like scale formation in hot water pipes, kitchen devices, water supply facilities, boilers, cooling towers, membrane clogging, declining efficiency of heat exchangers and reaction to the soap and formation of hard foam [2]. Moreover, soft water is preferred to be hard enough to prevent Nephritis. Hence, water hardness is one of the compounds which has to be removed and its process is called water softening [2]. WHO Recommendation for drinking water's hardness is based on maximum 500 mg/l calcium carbonate [3]. Numerous technologies which need adding chemicals for water softening, are chemical precipitation and ion exchange and those which do not need to add chemicals; include reverse osmosis, electro-dialysis, nano-filtration, crystallization, distillation and evaporation [4, 5]. These techniques have some problems such as increased sludge, permanent water hardness, water salts like sodium, annual high operation costs, sediment formation on membrane, which require an effluent post treatment and disposal of residual sludge [2, 6]. Recently, growing demand for high quality water has justified the development of modern and low cost technologies for hard and very hard water softening [6]. One of these techniques is electrochemical technology such as electrocoagulation process (EC), which is being used for the removal of ions, organic matters, colloidal and suspended particles, dyes, surfactants, oil and heavy metals from aqueous environments [7–11]. This procedure has a broader potential to improve the faults of other water softening equipments. Electrocoagulation process involves three stages; coagulant formation through dissolution of metal ions of anode reactor electrode, destabilization of pollutants, suspended particles and de-emulsification, and aggregation of instable phases and floc-forming [12]. Destabilization of pollutants, suspended particles and de-emulsification mechanism can be established through dispersed double layer compression, ion neutralization species existing in water and wastewaters, and flocs and sludge forming [9]. In this study, iron electrodes have been used in electrocoagulation (EC) process. Following equations, illustrate EC process in relation to iron electrode [10]: Removal of hardness from drinking water by electrocoagulation using iron electrodes P. D. Nemade 1* , K. T. Patil 2 , S. J. Kadbhane 2 , M. B. Patil 2 , Y. H. Tambe 3 1 * Professor, Department of Civil Engineering, MVPS’s KBT College of Engineering, Nashik, Savitribai Phule Pune University, Pune, Maharashtra, India. (Corresponding author: Email: pravin.nemade@gmail.com) 2 Faculty of Civil Engineering, MVPS’s, KBT College of Engineering, Nashik, Maharashtra, India 3 Research Scholar, Department of Civil Engineering, Dr. D.Y. Patil Institute of Technology, Pimpri, Pune, Savitribai Phule Pune University, Pune, Maharashtra, India. Email: yhtcivil.svpm@gmail.com Received Date : October 06, 2021 Accepted Date : October 27, 2021 Published Date : November 07, 2021 ISSN 2347 - 3983 Volume 9. No.11, November 2021 International Journal of Emerging Trends in Engineering Research Available Online at http://www.warse.org/IJETER/static/pdf/file/ijeter089112021.pdf https://doi.org/10.30534/ijeter/2021/089112021