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Popular Science: Is it possible to save the water from the micropollutants?

Not long ago, they were not known and even today there is still a lack of information about the potentially negative effects of all groups of “micropollutants”. At present, however, together with pesticides, they pose the most significant threat to drinking water quality. What substances do we actually drink and is it possible to remove them? A team of researchers from the T. G. Masaryk Water Research Institute, p. r. i. together with Zbyněk Hrkal and David Rozman from the Institute of Hydrogeology, Engineering Geology and Applied Geophysics of the Faculty of Science is dealing with the question.

Micropollutants, referred to as PPCPs (pharmaceuticals and personal care products), are substances that occur in water in the concentrations of nanograms to micrograms, their removal is complicated and therefore they are often still present in the water after treatment in the wastewater treatment plant (WWTP). It is a group of thousands of chemicals that enter sewers on a daily basis and often flow back into the taps.

Even though they are not yet included in Czech and European drinking water legislation, many of them could be potentially carcinogenic, teratogenic (causing birth defects and freak defects), with embryotoxic effects (negative effects on the unborn fetus), some are extremely stable and they may accumulate in the environment (e. g. carbamazepine), and at the same time the interaction between them could increase their negative effects (synergism).

Between 2015–2016, the monitoring Czech-Norwegian Research Programme project AQUARIUS was carried out in the locality of Horní Beřkovice, where the monitored micropollutants in already purified waste water were repeatedly detected. Therefore, in this study, the researchers focused on the quantification of 94 monitored PPCPs and their metabolites in the Jizera River basin, which affects the water quality of the Káraný Waterworks in Prague, which supplies a significant number of Prague residents. Monitoring took place at nine sampling points every month for two years.

The city of Mladá Boleslav, with a population of more than 44 thousand, and the psychiatric hospital at Kosmonosy, from which a large volume of pharmaceuticals gets into the WWTP and afterwards are discharged into the Jizera River, have an absolutely crucial impact. At the highest concentrations, in tens of micrograms per liter, oxypurinol (a drug used in elevated uric acid concentrations), diclofenac (an anti-inflammatory drug, the active substance increases the risk of a heart attack or stroke) were systematically present at higher concentrations (µg / l). tramadol (a painkiller, reduces attention and increases the risk of heart attack), lamotrigine (an antiepileptic drug, impacts the central nervous system, causes dizziness, headaches, etc.), and hydrochlorothiazide (diuretic, risk of developing tumors). Another 44 substances were detected at lower concentrations. The micropollutant concentration was influenced by the sampling time during the day, with the residence time being relatively short, closely linked to the local source. The flow rate was also important; elevated water discharges diluted the water and micropollutants were below the detection limit.

Pure clean water is not clean
Photo: K.Fraindová.

Furthermore, the researchers focused on the effectiveness of PPCP removal using two methods – artificial recharge and bank infiltration. Although both methods removed a substantial proportion of micropollutants, bank infiltration removes PPCPs in a more effective way. Using artificial recharge, acesulfame and oxypurinol in concentrations exceeding 100 ng / l were consistently present, as was the occasional occurrence of ibuprofen. Although the use of bank infiltration also caused the occasional occurrence of acesulfame and other substances, they were not present in all the samples. The higher bank infiltration efficiency can be explained by a higher proportion of clay minerals in the river bed, while artificial recharge takes place in clean sands and gravel.

As a solution for eliminating PPCPs in drinking water, the authors see more alternatives. The cheapest would be to optimize the production of drinking water depending on the flow rate, but due to the long-term low flow rates it could be difficult to implement. Another, but more expensive solution would be to equip the WWTP in Mladá Boleslav and pretreatment technology in Káraný with active carbon filters.

Hrkal, Z., Eckhardt, P., Hrabánková, A., Novotná, E., Rozman, D. (2018): PPCP Monitoring in DrinkingWater Supply Systems: The Example of Káraný Waterworks in Central Bohemia. Water, 10, 13 s.

Kateřina Fraindová

Published: Jul 29, 2019 07:15 AM

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