Improving Water Quality Affordably

Maintaining water quality simply is an invisible concept to most people, removal of contaminants and bacteria from water requires a great deal of effort from treatment systems and the humans which man them. Fundamental and clever engineering can help prevent waterborne illnesses and exposure to substances in water which are carcinogenic in nature. Engineers at Michigan Tech are developing an affordable low tech solution to improve the quality of water from municipal water tanks to remove micropollutants from the water using renewable materials, as published in 3 journals Journal of Molecular Liquids, Colloids and Surfaces A, and Journal of Hydraulic Engineering.

Most communities have one or more large water storage tanks with lines in to supply it with water and a line out. Most of these tanks the lines in and out are located at the bottom of the tank. Even though these tanks get refilled daily the water at the top of the tank is never used and as a result becomes stagnant. Despite most municipal water supplies being treated with chlorine that top layer can become breeding grounds for algae, bacteria, or waterborne illness such as E.coli and giardia. Due to the water not moving around these things can start to grow, it is best to keep water moving especially in the hotter regions. If there is a fire in the community or the water tank is significantly drawn down the community then will be drinking this stagnant water. After a fire and water tanks get drawn down it is known that people in that community get sick, this is the issue engineers are trying to remedy.

Engineers have developed shower head like attachments which can be added to new or existing tanks for minimal cost. PVC sprinkler pipes added to the top of the tank with a reverse sprinkler at the bottom of the tank moves water into the system which keeps all the water circulating in the tank alleviating the top stagnant water issue. Engineers hope that this easy, simple, low tech and affordable solution for improving water quality will be adopted by water quality managers.

Organic contaminants are not the only cause of contaminated water as very few municipal systems are equipped to adequately handle micropollutants such as hormones, microplastics, pharmaceuticals, nanoparticles in socks and synthetic fleece, antifungal compounds, and types of industrial waste that are present in low concentrations. Despite small microgram amounts of these pollutant in water they still have carcinogenic long term effects on health in aquatic creatures and humans. Retrofitting treatment plants to filter out micropollutants can be costly.

Researchers can up with the idea of adsorbing pollutant from water, which would occur by using molecules that stick to any surface. A polymer coated magnetic nanoparticle was tested to adsorb tonalide, bisphenol-A, triclosan, metolachlor, ketoprofen, and estriol. The magnetic polymer coated nanoparticles were very effective at adsorbing BPA and ketoprofen removing these pollutants with 95-98% effectiveness within 15 minutes using only 0.1 milligrams of the adsorbent. After the magnetic nanoparticles had completed their work magnets were used to remove them from the water. Once the polymer coated magnetic nanoparticle adsorbents were removed from the water they can be rinsed with a restorative methanol solution making them reusable which is a key component, in testing the nanoparticles were rinsed and restored 5 times before starting to show any signs of decreased effectiveness.

The next phase according to the researchers is to scale up for use in water treatment plants. Removal of micropollutants from water using this technology is not only affordable but sustainable and offers the potential to increase and further protection of aquatic and human health without having to undergo lengthy and expensive retrofitting of treatment plants.