Water is the source of life which is irreplaceable and crucial for every person and animal on the planet. Yet, to consume water, one must know that it is safe and does not contain any harmful elements. To ensure it, over centuries, people have developed numerous ways of purifying water by subjecting it to various procedures. Today, large cities and small settlements rely on the services of water treatment plants which largely still utilize technologies created many decades ago.
Water purification has always been essential for ensuring the well-being and normal functioning of society. There is historical evidence that people in Ancient Egypt were already familiar with basic processes such as coagulation helpful for water treatment. Nevertheless, it was not until the beginning of the 19th century when the civilization produced the first water purification plants, and it is important to establish how the technology has evolved to this day.
The technologies related to water treatment plants have been rapidly developing over the course of the last two hundred years. At the beginning of the 19th century, Scottish inventor Robert Thom became the first person in history to build a water treatment plant using a unique method involving slow sand filters (Blockley, 2020). Namely, water was poured into a container full of sand, tiny particles of which trapped the debris contained in the liquid; after finishing the process, the water was pure enough to be used for drinking. Yet, Thom’s plant did not have any pipes, and the water had to be delivered with the help of carts. Moreover, his technique did not ensure complete purification, and certain diseases such as cholera continued to spread through water. In the mid-19th century, John Snow, a British scientist, discovered that adding chlorine to water eradicated all the germs. The invention of chlorination enabled authorities to install mandatory filters involving the slow sand technology combined with chlorination in major cities. The chlorination method for water disinfection is still used in the majority of countries on the planet, including in the U.S.
At the end of the 19th century, a new method of fast sand filtering was implemented in plants in the U.S. which utilized the new approach. American scientist George W. Fuller was the man behind the innovation. He spent ten years conducting research in the field of water treatment and developed a technology which demonstrated an increase in the speed of filtration of sixty times when compared to slow sand filters (Slack, 2017). To facilitate the purification process, he used aluminum sulfate before the primary filtration procedure (Slack, 2017). The chemical compound was effective in causing large debris particles in water to coagulate and thus be easily removed, which reduced the time required for the filtration to complete. It is important to note that aluminum sulfate, when used in small volumes, is not dangerous for people’s health. Eventually, George W. Fuller integrated the rapid sand filtration technology, also known as mechanical filtration, in a plant in Little Falls, New Jersey. As a result, the facility had a capacity to clean thirty million gallons per day, which indicated a breakthrough in the sphere of public health.
The chlorination method continued to be the primary way of treating water at the beginning of the 20th century, yet its negative effects soon were discovered and raised concerns of the public. For instance, today, it is known that exposure to chlorine may trigger airway, skin, and eye irritation, coughing, sneezing, sore throat, and other unpleasant symptoms (“The facts about chlorine,” n.d.). The dissatisfaction with the chemical encouraged scientists to experiment and seek alternative ways for water treatment. Belgium used a mixture of ferric chloride and calcium hypochlorite, which was effective in purifying the country’s public water supply (Twimz Animatez, 2017). While in France, researchers successfully utilized ozone as a means of disinfection. In the second half of the 20th century, there were many technological advances in the field of water purification and reverse osmosis was the main innovation among them. Reverse osmosis involves pushing water through a semipermeable membrane which traps contaminants and other impurities and producing clean water as a result. This solution is extremely scalable since it can be applied both at large industrial facilities and at home for personal use.
Today, modern water treatment plants vary in their approaches and particular technologies, yet the most advanced ones follow the same steps necessary for achieving ultimate purification. The process begins with the coagulation and flocculation stage, which implies adding chemicals such as aluminum sulfate to water, causing sediment, bacteria, and organic materials to coagulate. The following step takes place in a flocculation basin where the solution of water and the coagulants are physically mixed together, which results in the formation of a floc (Concerning Reality, 2018). The second stage is called sedimentation, which implies moving the water into a tank where floc particles start to settle out, turning into sludge which then gets removed from the tank. After the debris is removed, the next step is filtration which is usually performed with the help of sand filters. The process is simple, the water goes through several layers of sand and exits as clear yet still containing bacteria (Concerning Reality, 2018). To ensure that the water is safe to drink, disinfection is conducted by adding chlorine to the water or subjecting it to ultraviolet radiation. It is evident that the process of water treatment has not changed significantly over the past hundred years and involves many steps developed many decades ago.
Water purification is essential for maintaining public health and safety, and it is crucial to understand how the technologies currently utilized in water treatment plants were discovered. Robert Thom was a pioneer in this field since he designed the first facility for purifying water at the beginning of the 19th century using slow sand filtration. Then came chlorination, a technology which is still commonly used even in the most advanced plants. The introduction of mechanical filtration also revolutionized the field and made the treatment of large volumes of water possible. Today, water purification facilities use a four-stage approach which includes coagulation and flocculation, sedimentation, filtration, and disinfection.
Blockley, D. (2020). Creativity, problem solving, and aesthetics in engineering. Springer.
Concerning Reality. (2018). How do water treatment plants work? [Video]. YouTube.
Slack, H. (2017). George W. Fuller and the purification of water. SciHi Blog. Web.
The facts about chlorine. (n.d.). The New York State Department of Health. Web.
Twimz Animatez. (2017). History of water purification [Video]. YouTube.