DELOACH BLOG

Clean water is essential for sustaining life, and ensuring its purity is a priority for environmental agencies worldwide. However, a growing concern has emerged in recent years – the presence of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in drinking water. PFAS are persistent, human-made chemicals widely used in various industrial and consumer products, posing a significant threat to water sources and public health. Here, we'll explore the strategies and challenges involved in removing PFAS from drinking water, shedding light on the ongoing efforts by environmental agencies to manage and dispose of these persistent chemicals.

Understanding PFAS Contamination

PFAS contamination is a complex issue stemming from the widespread use of these chemicals in industries such as manufacturing, firefighting, and even everyday household products. These substances are known for their heat, water, and oil resistance, making them valuable for various applications. However, their persistence in the environment has raised serious concerns.

PFAS enter water sources through various pathways, including industrial discharges, wastewater treatment plants, and the use of firefighting foams. Once in the water, PFAS can accumulate over time, threatening aquatic ecosystems and, ultimately, human health. Long-term exposure to PFAS has been linked to adverse health effects, including developmental issues, immune system suppression, and an increased risk of certain cancers.

Strategies for Removing PFAS from Drinking Water

Addressing PFAS contamination requires a multifaceted approach, combining advanced water treatment technologies with comprehensive regulatory measures. Several strategies have been employed to remove PFAS from drinking water, each with its challenges.

Activated Carbon Filtration

One widely adopted method for PFAS removal is activated carbon filtration. Activated carbon has a high affinity for PFAS compounds, effectively adsorbing them from the water. However, the efficiency of this method can be influenced by factors such as the type of activated carbon used, the water's chemical composition, and the presence of other contaminants. Additionally, the disposal of used activated carbon loaded with PFAS poses a significant challenge, as it can contribute to environmental contamination if not handled properly.

Ion Exchange Resins

Ion exchange resins are another technology employed to remove PFAS from drinking water. These resins replace PFAS ions with less harmful ions, effectively capturing and removing them from the water. While ion exchange can be highly effective, managing the used resins saturated with PFAS is challenging. Proper disposal methods must be implemented to prevent the release of these persistent chemicals back into the environment.

Advanced Oxidation Processes (AOPs)

Advanced Oxidation Processes (AOPs) involve using powerful oxidants to break down PFAS compounds into non-toxic byproducts. Techniques such as ozonation, ultraviolet (UV) irradiation, and hydrogen peroxide treatment fall under AOPs. While these methods show promise in PFAS degradation, they can be energy-intensive and may produce secondary pollutants. Balancing effectiveness with environmental impact remains a key challenge in implementing AOPs for large-scale water treatment.

Water demineralization is also called deionization and is a process known as “Ion Exchange.”

In simple terms, water demineralization is “Water Purification.” The process involves removing dissolved ionic mineral solids from a feed-water process, typically for “Industrial” water applications. Still, it can also be utilized to remove dissolved solids from a water process for “Aquaculture,” “Food and Beverage,” and the “Municipal” markets.

Why is demineralization utilized? It can remove dissolved solids to near distilled water quality at a much lower capital and operational cost than other treatment processes such as membrane softening (Reverse Osmosis). Demineralization applies the science known as “Ion Exchange,” which attracts negative and positive charged ions and allows either to attach themselves to a negative ion depending on their respective current negative or positive charge during what is known as a resin cycle. In other technical articles, we will explore and go into more specific details on the science of the ion exchange process. Water that has dissolved salts and minerals has ions, either negatively charged ions known as “Anions” or positively charged ions known as “Cations.” To treat the water and remove these contaminants, the ions in the water are attracted to counter-ions, which have a negative charge. In a demineralization treatment process, there are pressure vessels that hold resin beads which are typically made of plastic. The beads are made from a plastic material with an ionic functional group that allows them to hold and maintain an electrostatic electrical charge. Some of these resin groups are negatively charged, referred to as “Anion” resins, while others hold a positive charge and are called “Cations” resins.

There are different applications to apply Ion exchange technologies, which is why you will often hear different terminology interchanged like deionization and demineralization. The raw water quality and the specific application will dictate the type of ion exchange process needed. For example, if the water contains a high level of hardness, the water will most likely contain Ca2+ or Mg2+ dissolved solids possessing a positive charge. To replace these hard ions, it is typical to utilize a resin bed with a salt ion like Na+. As the water passes over the resin bead material within the pressure vessel. The hard ions are replaced with the salt ion; therefore, all the hardness within the water is removed. However, the water will now contain a higher concentration of sodium ions, and this must be considered during the evaluation and selection process of the type of resin material to utilize for the specific application. If the water application requires high purity and the removal of as many solids as possible, then the term or process selected is referred to as demineralization.