Removal of Hardness from Water Samples by a Carbonation Process with a Closed Pressure Reactor

Min Ahn,Choon Han,Thriveni Thenepalli,Ramakrishna Chilakala

doi:10.3390/w10010054

Min Ahn, Choon Han + Show 2 more

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https://doi.org/10.3390/w10010054

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Abstract

One of the undesirable characteristics of some ground and natural water sources is hardness. Hard water can cause many problems around the world, including increased scaling on water pipes, boilers, atopic eczema and odd-tasting drinking water. Hardness in natural water is caused by dissolved minerals, mainly calcium and magnesium compounds. According to the Water Quality Association (WQA) and the United States Geological Survey (USGS), hard water is classified based on the Ca2+ and Mg2+ ion concentration in waters, as follows: 0–60 ppm as soft; 61–120 ppm as moderately hard; 121–180 ppm as hard and more than 180 ppm as very hard water. Most water utilities consider a hardness level between 50 and 150 ppm of CaCO3 as publicly acceptable. The present study investigated the effects of a carbonation process on the removal of hardness in different water samples. Currently, a wide variety of hardness removal technologies are available. Among those conventional methods, carbonation is an inexpensive process which can be used for the removal of Ca2+ and Mg2+ ions from hard water. This study measured the hardness levels of 17 different water samples using the ethylene diamine tetra acetic acid (EDTA) method. Among these, Seoul outdoor swimming pool water (140 ppm) samples showed high concentrations of Ca2+ and Mg2+ ions. The hardness of the different water samples was reduced by 40–85% by a carbonation process with a closed pressure reactor for a 5 min reaction time.

Highlights

Hardness is one of the common water quality problems throughout the world.A total of 70% of the earth’s surface is covered by water
The main objective of this study is to describe the removal of hardness in water by a carbonation carbonate (PCC) and magnesium carbonate from hard water samples were investigated
The results clearly indicated that the hardness removal efficiency temperatures: 25, and enhanced up to 60–70% by the carbonation process with 21 g of CO2/L for 5 min reaction at 40 °C

Summary

Introduction

Hardness (hard water) is one of the common water quality problems throughout the world.A total of 70% of the earth’s surface is covered by water. Hard water is found at a rate exceeding 85%, as water picks up minerals such as magnesium and calcium ions from rocks and soil, leading to the hard water. Knowing the hardness of water is important when evaluating its use as a domestic or industrial water supply. Hard water interferes with laundering, washing, bathing and personal grooming [2]. Hard water utilization in the home can lead to other issues as well. It affects soap and detergent used for cleaning because soap used in hard water combines with the high amount of minerals to form a sticky sludge. Bathing with soap in hard water can deposit this sticky residue onto the skin and can lead to irritation under slightly acid conditions

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