By Peter S. Cartwright, PE
In Part 1, we presented the case for concern about the presence of PPCPs in our drinking water, particularly in regard to health risks. Part 2 addresses possible activities and technologies to mitigate the problem and offers a prediction for the future.
What can we do about this issue?
Obviously, we can (and should) all become personal stewards of our own environment. This includes more diligence about what we throw down the drain, as well as our overall water usage. There is evidence that people are becoming more knowledgeable about waste in general, and more careful about how they dispose of unused pharmaceutical products, for example. Many pharmacies are accepting them at no charge and at the very least, more consumers are disposing of them in the trash rather than the toilet. We must individually monitor our personal practices regarding purchases and disposal of personal care products. Fortunately, this attitude seems to be taking hold, albeit very slowly. There is an exciting paradigm shift slowly happening in the manufacturing and agricultural industries: the trend is toward water conservation, as well as wastewater recovery and reuse.
There is significant federal activity addressing PPCP issues. One bill introduced in the Senate in 2015, Personal Care Products Safety Act, amends the Federal Food, Drug and Cosmetic Act to require cosmetics companies to submit, to the US Food and Drug Administration (FDA), a list of the chemicals in their products and to report any serious adverse health events associated with their products.(1) It has not yet been enacted into law. A new US EPA rule requires companies that manufacture chemical substances known as nanoscale materials to submit a report containing manufacturing data and “existing information concerning environmental and health effects.” These materials are defined as particles of sizes of one to 100 nanometers (a nanometer is 0.001 µ).(2) Individual states can enact their own contaminant concentration limits for drinking water, providing they are more stringent than existing US EPA standards; many states have chosen to do so for specific contaminants.
The huge number of chemicals with their innumerable structures and properties presents a significant challenge for drinking water treatment. The good news is that the concentrations of almost all of these contaminants can be reduced with existing water treatment technologies. On the other hand, the most complete removal will probably involve not one, but several technologies, probably used in combination.
Although current biodegradation technologies employed by municipal wastewater treatment plants have little or no effect on overall PPCP removal,(3,4) much scientific activity is underway on new microorganism approaches; improvements in remediation of these contaminants through this route may be possible. It appears that in-situ bioremediation offers promise by using customized bacteria designed to treat localized aquifers in certain cases. Unfortunately, most municipal water and wastewater treatment plants are significantly underfunded and the funding for new technologies are generally not available.
Activated carbon (AC), long employed for removal of chlorine, certain gases and many dissolved organics, is an effective technology for many of the lower molecular-weight organic contaminants in PPCPs. Utilizing surface adsorption, AC filters capture these chemicals and can be very effective. They ultimately require replacement; however, the exhausted resins can usually be safely landfilled.(3,4,5,6)
The family of membrane technologies, microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO), are very effective for the reduction of a wide range of contaminants. MF and UF will target higher molecular-weight PPCP organic compounds, while NF and RO are most effective on the more ionic (polar) and lower molecular-weight organic compounds. These membrane technologies are designed to reject the contaminants in a separate concentrate stream, which is usually discharged to drain. They are most effective when used to treat water specifically for drinking and culinary purposes. Of course, these technologies don’t destroy PPCPs; they just redirect them into the drain. Such notorious contaminants as lead and nitrate are also readily removed by RO.(4,6,7,8,9) Table 1 roughly summarizes the PPCP removal properties of both activated carbon and the membrane technologies.
Distillation is also an effective technology for reduction of waterborne contaminants. This process involves boiling the water and then condensing the water vapor to produce purified water. A potential problem is that those organics with boiling points close to that of water may also evaporate and end up in the distillate. Activated carbon can be utilized to help mitigate this problem. A downside of distillation is the energy required to boil water and to cool the distillate.
The technologies known as advanced oxidation processes (AOPs), utilize destructive technologies such as UV irradiation, ozone and hydrogen peroxide in various combinations and concentrations to break organic bonds and generally produce more benign chemicals. Depending on the characteristics of the chemicals resulting from these oxidation processes, they may or may not be less dangerous; however, the resulting chemicals may be more easily removed by the other processes. In the wastewater treatment industry, AOPs are (currently and) primarily used to inactivate (kill) microorganisms.(3,4,6,7)
It may be that harnessing the (elusive) hydroxyl radical (●OH) will be required to more completely break down some compounds. The technologies to produce this very powerful oxidant have escaped widespread practical application so far, but it should become viable in the not-too-distant future. The POU undersink RO units (designed to treat drinking water for a single tap) so readily available from water conditioning dealers and DIY stores have been shown to be capable of removing an estimated 60 to 80 percent of all PPCPs. Because virtually all incorporate both activated carbon and RO membrane technology, they should all work equally well. This is the best possible solution to the PPCP issue at this time. Although less commonly available, POU distillers are also available.
Regardless of the treatment technology selected, they all require maintenance, primarily dictated by the characteristics of the water to be treated. Usually, the issue is suspended solids (dirt) in the water supply or certain chemicals that may become insoluble during the purification process. For example, with POU RO units and distillers, they should be fed with softened water.
Because the water conditioning industry includes some less-than-desirable characters selling foo-foo dust or unproven technologies, it is imperative that only units that have been validated by credible third-party organizations be selected. Fortunately, excellent manufacturing and performance standards for each technology have been developed. For POU RO units, NSF/ANSI 58 establishes manufacturing and performance protocol and several ANSI-accredited organizations are capable of certifying a unit to meet this standard. They include Canada Standards Association (CSA), IAPMO Research and Testing, NSF International, Water Quality Association (WQA) and Underwriters Laboratories (UL). These organizations provide certification that treatment units meet the appropriate manufacturing and performance standards associated with their specific technology. It is important that the product label include a statement that the unit complies with the requirements established by the appropriate standard.
Philosophically, I have always had an issue with the requirement to deliver the high-purity water we require for drinking and cooking when we actually only consume about one percent of what comes into the house. Without dual piping systems in the home, however, choices are limited. If bottled water manufacturers’ labels confirm that the product is treated by RO or distillation, this product should be acceptable. On the other hand, BPA plastic is now being discontinued and its replacement, BPS, is under suspicion for causing endocrine-system problems, Then there is the solid-waste issue. My suggestion is that if you want to take your drinking water with you, get a stainless steel water bottle and fill it up from your own RO unit or distiller when you leave your residence.
So, what does the future hold? First, remember that a human health link to PPCPs in drinking water has not yet been established. My personal predictions are:
1. The concentrations of PPCPs will increase in our water supplies.
2. A risk to human health from these will eventually be identified.
3. The immediate solution will be to put a drinking water treatment system in each home, initially consisting of a POU RO or distillation unit, as described above.
4. A fundamental change to the way we use our water supplies may be required, accessing only this treated water for our individual drinking and culinary requirements.
5. More effective and less expensive wastewater treatment technologies will be developed to facilitate reuse.
6. People will become better water stewards, installing dual-piping systems, collecting and using rainwater and graywater for non-potable applications.
7. There will be greater use of wetlands and innovative processes for treating and reusing wastewater from virtually all sources.
In this writer’s opinion, the vast (and still growing) array of contaminants in our drinking water will inevitably result in the identification of new health risks. In the meantime, the concerned consumer can reduce self-exposure with a simple, economical water purification unit feeding a single tap dedicated to drinking and culinary purposes. Additionally, we must all recognize the limits of our finite water supply and conserve, collect and reuse. Just as the knowledge of water contamination has resulted in the elimination of virtually all waterborne pathogens and mitigated the exposure to heavy metals, arsenic, etc., we need to develop a science and risk-based understanding of the PPCP issue in order to determine how to most effectively minimize its effect. Creativity and innovation are human characteristics and once we know the chemistry of the problem, I am confident that new products, processes and improvements will appear on the scene. These are exciting times for the water/wastewater treatment industry. We have only begun to scratch the surface and the best is yet to come!
(3) Mohammad Feisal Rahman et al. “Advanced Oxidation Treatment of Drinking Water: Part 1. Occurrence and Removal of Pharmaceuticals and Endocrine-Disrupting Compounds from Lake Huron Water.” Ozone: Science & Engineering, 32; 217-229.
(4) M.F. Rahman et al. “Endocrine disrupting compounds (EDCs) and pharmaceuticals and personal care products (PPCPs) in the aquatic environment: implications for the drinking water industry and global environmental health.” Journal of Water and Health. 07.2 2009.
(5) Gregory H. LeFevre et al. “Occurrence of Neonicotinoid Insecticides in Finished Drinking Water and Fate During Drinking Water Treatment.” Environmental Science & Technology Letters, April 2017 DOI: 10.1021/acs.eslett.7b00081.
(6) Shane Snyder et al. “Pharmaceuticals in the Water Environment.” NACWA (pp. 22, 23).
(7) World Health Organization 2012. Pharmaceuticals in drinking-water. ISBN 978 92 4 150208 5 (p. 28).
(8) T. U. Kim, G. Amy, J. E. Drewes. “Rejection of trace organic compounds by high-pressure membranes.” Water Sci Technology, 2005; 51:335-44 16003994.
(9) Rosa Boleda, et al. “Winning the Wastewater Drug War.” Pollution Engineering, May 2010.
Three referenced website links listed in Part 1 were not valid. The correct website links are as follows:
Reference 2: www.ewg.org/skindeep/2004/06/15/exposures-add-up-survey-results/
Reference 3: http://newsnetwork.mayoclinic.org/discussion/nearly-7-in-10-americans-take-prescription-drugs-mayo-clinic-olmsted-medical-center-find/
Reference 5: http://wisconsinwatch.org/2013/ 05/13/studies-endocrine-disruptors-common-in-mn-waters/
About the author
Peter Cartwright entered the water and wastewater treatment field in 1974 and has had his own consulting engineering company since 1980. He is a graduate of the University of Minnesota, with a degree in Chemical Engineering and is a registered Professional Engineer in that state. Cartwright has authored over 300 articles, written several book chapters, presented more than 300 lectures around the world and holds several patents. He is a recipient of both the Award of Merit and Lifetime Member Award from the Water Quality Association and is the Technical Consultant to the Canadian Water Quality Association. Cartwright was the 2016 McEllhiney Distinguished Lecturer for the National Ground Water Research and Educational Foundation. He can be reached at firstname.lastname@example.org; his website is www.cartwright-consulting.com.