Drugs in our wastewater
Some of the drugs that we consume are discharged into the municipal wastewater via our urine. The European Commission has drawn up a list of 4,000 active pharmaceutical ingredients that are likely to end up in wastewater: contraceptives, antidepressants, antibiotics, anti-inflammatories, anticancer drugs, contrast agents used in medical imaging, etc. Some of them have an impact on the environment, especially fish and amphibian reproduction. This is particularly true of endocrine disruptors, which influence our hormonal system. However, in most countries there are currently no regulations regarding the treatment of these drug residues. One of the components of the MERMISS project consists in establishing and drawing up a vigilance list for the most toxic pharmaceutical residues on a European scale. This will allow innovation efforts to concentrate on treating these substances.
The municipality of Aarhus, Denmark’s second-largest city, decided to tackle the drug residues found in wastewater when planning the city’s new university hospital. This move led to the creation of a consortium consisting of Aarhus University Hospital, Herning and Aarhus water utility companies, the Danish Technical Institute, Krüger, the Technical University of Denmark, Aarhus University and Air Liquide. It was tasked with identifying the most efficient and environmentally friendly way to remove pharmaceuticals from wastewater: the MERMISS project (Environmentally friendly treatment of highly potent pharmaceuticals in hospital wastewater). Initial tests began at Aarhus University Hospital with wastewater from the oncology department. The scope was then expanded to include Herning’s municipal wastewater, and finally effluent from the municipal WWTP in Aarhus was polished. The aim was to draw up a suitable treatment framework.
Diffuse pollution
The question was as follows: should they treat the wastewater at the hospital’s own treatment plant or send it for treatment at the municipal level? With the growing popularity of outpatient care, the number of patients monitored at home by Aarhus University Hospital rose by 34% on average between 2007 and 2015. As a direct consequence, pharmaceutical pollution is no longer limited to the hospital’s wastewater.
To make the right decision, Aarhus University Hospital’s Environmental Coordinator, Thomas Møller, studied patients’ medical data. Only 4% of the total prescribed pharmaceuticals are consumed in hospitals. The results are indisputable: to limit the environmental impact, the municipal water must be treated.
Biological efficacy
“We chose to work with Krüger because they offer technical solutions to eliminate drug residues that are effective and economical in one,” states Thomas Møller. Aarhus hospital and Krüger decided on MBBR (Moving Bed Biofilm Reactor) technology. This biological treatment technology relies on micro-organisms that grow on plastic media. Due to the project’s configuration, they will develop specific “skills” for treating pollution that is not readily biodegradable.
« “Unlike traditional activated sludge, this technology facilitates the degradation of complex organic matter using slow-growing bacteria,” states Christina Sund, Business Development Director at Krüger.
More bacteria, less ozone
Unprecedented water treatment at the new hospital
In the Danish city of Herning, where the ambitious hospital complex of Gødstrup is being built to serve western Jutland from 2020 onward, the question of treating drug residues is key. “We are very keen to provide high-quality drinking water both now and in the future, and therefore not discharge drug residues into the environment,” highlights Niels Møller Jensen, CEO of Herning Vand, the city’s water utility company. “Yet 95% of this residue is discharged by people outside the hospital. We must therefore treat the water in the municipal plants.” Herning Vand and Krüger worked together to find an effective and affordable solution to this problem. Once again, the solution chosen was MBBR (Moving Bed Biofilm Reactor) technology. “We discovered that nature was much more efficient than we thought: with MBBR technology, we will be able to eliminate drug residues in all the city’s wastewater,” concludes Niels Møller Jensen.
This technology can also be used as a post-treatment step for effluent polishing, after the “conventional” wastewater decontamination process. For complete treatment, e.g. for hospital wastewater (cf. above), the system consists of six MBBR reactors in series. The post-treatment concept harnesses three reactors using the same technology, supplemented by ozone oxidation to remove all target pharmaceuticals to PNEC (predicted noeffect concentrations) level. The more effective the biological treatment, the less ozone needs to be added – a more expensive and energy-consuming process. The results of the experiment are extremely conclusive. Up to 90% of the pharmaceutical residues found in the municipal wastewater have been removed. Which opens up a world of opportunities!
“We are just about to launch a new project to test this purely biological elimination technology on a larger scale,” states Thomas Møller. “As MBBR technology is so inexpensive, it becomes relatively costeffective to eliminate pharmaceuticals from wastewater, even in municipal wastewater treatment plants. Krüger’s technology can be a game-changer, allowing us to meet the challenge of pharmaceutical pollution in wastewater.”
