Research on drinking water purification technologies for household use by reducing total dissolved solids (TDS).

Bill B Wang,Mahendra Singh Dhaka

doi:10.1371/journal.pone.0257865

Abstract

This study, based in San Bernardino County, Southern California, collected and examined tap water samples within the area to explore the feasibility of adopting non-industrial equipment and methods to reduce water hardness and total dissolved solids(TDS). We investigated how water quality could be improved by utilizing water boiling, activated carbon and sodium bicarbonate additives, as well as electrolysis methods. The results show that heating is effective at lower temperatures rather than long boils, as none of the boiling tests were lower than the original value. Activated carbon is unable to lower TDS, because it is unable to bind to any impurities present in the water. This resulted in an overall TDS increase of 3.5%. However, adding small amounts of sodium bicarbonate(NaHCO3) will further eliminate water hardness by reacting with magnesium ions and improve taste, while increasing the pH. When added to room temperature tap water, there is a continuous increase in TDS of 24.8% at the 30 mg/L mark. The new findings presented in this study showed that electrolysis was the most successful method in eliminating TDS, showing an inverse proportion where an increasing electrical current and duration of electrical lowers more amounts of solids. This method created a maximum decrease in TDS by a maximum of 22.7%, with 3 tests resulting in 15.3–16.6% decreases. Furthermore, when water is heated to a temperature around 50°C (122°F), a decrease in TDS of around 16% was also shown. The reduction of these solids will help lower water hardness and improve the taste of tap water. These results will help direct residents to drink more tap water rather than bottled water with similar taste and health benefits for a cheaper price as well as a reduction on plastic usage.

Highlights

The concentration of total dissolved solids(TDS) present in water is one of the most significant factors in giving water taste and provides important ions such as calcium, magnesium, potassium, and sodium [1,2,3]
When added to room temperature tap water, there is a continuous increase in TDS of 24.8% at the 30 mg/L mark
The new findings presented in this study showed that electrolysis was the most successful method in eliminating TDS, showing an inverse proportion where an increasing electrical current and duration of electrical lowers more amounts of solids

Summary

Introduction

The concentration of total dissolved solids(TDS) present in water is one of the most significant factors in giving water taste and provides important ions such as calcium, magnesium, potassium, and sodium [1,2,3]. Many plants are effective in ensuring the quality and reduction of these contaminants, but often leave out the secondary considerations, The United States Environmental Protection Agency (US EPA)’s secondary regulations recommend that TDS should be below 500 mg/L [2], which is supported by the World Health Organization(WHO) recommendation of below 600 mg/L and an absolute maximum of less than 1,000 mg/L [3] These substances form calcium or magnesium scales within water boilers, heaters, and pipes, causing excess buildup and drain problems, and nitrate ions may pose a risk to human health by risking the formation of N-nitroso compounds(NOC) and less public knowledge about such substances [12,13,14,15]. By determining a better way to lower TDS and treat water hardness, water standards can be updated to include TDS levels as a mandatory measurement

Materials and methods

Findings

Conclusion