Hardness and Fluoride Removal Efficiency of Groundwater: Use of Physiochemical Methods in Water Purification at Anuradhapura District Dry Zone in Sri Lanka

Abstract

The limitation of drinking water critically affects the day-to-day life of most of the community in Sri Lanka as well as in the world. The community in the dry zone of Sri Lanka has especially been facing this difficulty for a long period. It is identified that high concentration of Calcium, Magnesium and Fluoride in groundwater is the main reason for this situation. Even though there are various methods used for water purification, the problem remains the same for rural communities and some urban communities. This study is focused on installing the most suitable and effective water treatment pilot plant and the collection of data to design an industrial water treatment plant. Anuradhapura and Mihinthale were selected as the study area based on the data collected during field visits. A pilot plant with a Reverse Osmosis (RO) membrane was installed and operated for two months of a time period, at the army camp Padulagama while comparing it with an industrial treatment plant at Rajarata University. According to the physical and chemical parameter results it was revealed that 32.43% of the raw water was successfully purified. Hardness and Fluoride concentration could be reduced up to 42.07 mg/l and 0.06 mg/l respectively. The common parameters which were reduced due to the use of RO membrane were also analyzed and found acceptable. Operation lapses and difficulties in treatment plants were identified and rectifications were carried out successfully. Designing of a RO water treatment plant with a pre-treatment unit and maintenance, regeneration and replacements were conducted. Recommendations were made for appropriate discharging methods of the rejected water from the RO membrane.