Impact emerging contaminants water supplies - Addressingissue

Impact of emerging contaminants to water supplies - Addressing the issue

10:25 AM, 16th May 2018
Impact of emerging contaminants to water supplies - Addressing the issue
Water recycling or water reuse initiatives are on the rise globally to augment current water supplies and reduce reliance on seasonal sources.

By Dr Tarun Anumol (PhD)

Have you ever wondered if the glass of water you are going to drink is the same as that consumed by a celebrity of yesteryear? Or, if the water you are bathing in is the same used by a thirsty dinosaur several million years ago? It very likely may be, as the water on Earth has stayed mostly the same over several billion years, because of the way the water cycle works.

The difference is that the water we use today may contain tiny amounts of manufactured chemicals like pharmaceuticals, personal care products (ingredients from perfumes, and antimicrobial soaps) plasticizers, fire retardants used in furniture, detergents, insect-repellents, contraceptive hormones and even a little bit of caffeine! This group of chemicals, that has recently been detected in our water supplies at trace levels and normally through anthropogenic influences, are broadly classified as ‘emerging contaminants’. These chemicals are often used to improve our lives but also find their way into our water supplies. In fact, numerous reports have suggested these chemicals are found in rivers, lakes and drinking water supplies globally, and at increasing frequency.

A few of these emerging contaminants are known to have adverse biological effects on humans and wildlife but toxicological data for a vast majority of them is still unknown and under review. Furthermore, the longterm effects of being exposed to low dose concentrations of these compounds in  water and potential synergistic effects they may have over time in humans is currently unknown. With over 130 million known chemicals in the world today, it should not be a surprise to find that some of them are entering the environment. Very few, if any, emerging contaminants are regulated in water around the world.

Population explosion, urbanization and changes to climate are some factors that tax our limited water supplies. It is estimated that more than two billion people living on this planet currently experience water stress. With water resources being stretched, we are forced to look for alternate sources of water to sustain our daily needs as well as industrialization. This leads to sources that may differ from traditional ‘pristine’ waters, and include those that have been used for many decades and may be influenced by agricultural runoff, as well as industrial and domestic wastewater that can add chemicals, including emerging contaminants, to the water.

Water recycling or water reuse initiatives are on the rise globally to augment current water supplies and reduce reliance on seasonal sources. These schemes essentially rely on treating wastewater to a sufficiently high standard so that it can be used again for several purposes. Successful implementation of water reuse systems requires a thorough knowledge of the contaminants in wastewater, treatment processes to remove them, and the ability to test water accurately to ensure safety.

Traditional water treatment plants were designed to remove dangerous microbes, bulk organic parameters like color, turbidity, odor and a few regulated chemicals that were known at the time. Indeed, water treatment processes drastically improved water sanitation and reduced water-borne diseases. For example, the process of water disinfection by chlorination, which started in the early 1900’s was so effective at killing pathogens that it dramatically reduced waterborne illness and increased lifeexpectancy1.

However, traditional water treatment processes were not designed for, and hence are not as effective at, removing many of the emerging contaminants we detect in water today. Several studies have shown that treatment processes like coagulation, flocculation and disinfection remove very little if any of the pharmaceuticals, perfluorinated compounds, bisphenol A, industrial additives and other compounds which means that once these emerging contaminants are introduced to the water system, they are very difficult to remove by traditional water treatment processes and tend to persist for a long time.

To better deal with these emerging contaminants, advanced water treatment processes like nanofiltration, reverse osmosis (RO) and advanced oxidation processes (AOPs) like ozonation are being implemented as part of newer advanced water treatment plants.

These processes can remove many (but not all) of the emerging contaminants but they are also expensive and energy intensive. Both RO and nanofiltration are physical membrane-based separation processes that are effective at removing a vast majority of emerging contaminants but lead to a small highly concentrated waste stream of these emerging contaminants that still need to be disposed of – which can be very difficult and expensive. AOPs are chemical oxidation processes where the aim is to mineralize a chemical to CO2 and H2O.

These processes have been thought to be effective at eliminating many emerging contaminants in water too. However, most of these contaminants are not mineralized with the AOP doses used in water and so actually result in the parent compound being converted into a transformation product. These transformation products can sometimes be more toxic than the parent compound in water. In fact, the disinfection process that kills pathogens and saves so many lives can also react with organic matter like emerging contaminants in the water to form new compounds known as disinfection byproducts. Some disinfection byproducts can be extremely toxic and have even been linked to cancer2.

Indeed, balancing the use of disinfection to prevent waterborne illness with formation of toxic disinfection byproducts is critical and a necessary field of current and future research: While new water treatment technologies are able to attenuate many emerging contaminants, further study of current and the development of new technologies is still needed. The development of advanced analytical instrumentation like tandem quadrupole mass spectrometers has made it a lot easier to detect and quantify these emerging contaminants.

Improvements to sensitivity and increased access to advanced analytical instrumentation has resulted in these compounds being detected at extremely low levels (nanaogram per liter) in our waters. Further, innovations in hardware and software have also made these tools affordable, accessible and more easy to use for new audiences.

The development of high-resolution accurate-mass mass spectrometers has also allowed researchers to identify new and previously unknown chemicals in the environment. The identification of every single chemical present in the water, from the several million that are in production is tedious and economically impractical. Therefore, a new paradigm of testing that combines chemical analysis with biological testing has been proposed. In this method, scientists run the (water) samples through a battery of biological assays that measure different toxicological end-points to determine the safety of the water sample. When an effect is detected in any of these biological tests, the water is analyzed to detect the chemicals present in them that cause the adverse biological result.

This information can then be used to create focused treatment technologies for the specific chemicals causing the biological effects in the water. This technique of combining biological testing with chemical analysis is known as ‘effects-directed analysis’ and is an effective method to not only screen water samples but also protect public safety.

The continued development and creation of new chemicals to improve quality of life and support our future demands is important. However, these processes should be balanced out with consideration to protect our precious natural resources and environment - essential to healthy life. While source control is the most effective way to prevent new and emerging contaminants from entering our environment and water sources, the continued development of novel and effective water treatment technologies to attenuate them when they get into our water is critical.

Also, technology advancements and continued development of sophisticated analytical tools to identify, measure and monitor levels of these emerging contaminants in the environmental is essential to maintaining safe water and protecting public health.

Author: Dr Tarun Anumol (PhD), Global Environment Industry Manager, Agilent Technologies

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1. A Century of U.S. Water Chlorination and Treatment: One of the Ten Greatest Public Health Achievements of the 20th Century. Available at: [Accessed April 2018]

2. Richardson, S. D., et al. (2007). Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection by-products in drinking water: A review and roadmap for research.” Mutation Research-Reviews in Mutation Research, 636(1-3): 178-242.



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