Success Story: CORNET project AOPTi
The importance of innovative treatment technologies for elimination of micropollutants in wastewater
Micropollutants, such as active pharmaceutical ingredients, pesticides and other chemicals are continuously released into municipal wastewater. However, urban wastewater treatment is not designed to remove these substances. On average, about 20 to 50% of micropollutants are eliminated by conventional wastewater treatment processes. The introduction of the Water Framework Directive has provided Europe with the legal framework to create a single water policy. Environmental quality standards for surface waters currently exist for 45 priority substances and are to be met by 2027. A watch list contains further substances for which legal regulations are expected in the coming years. Therefore, solutions for the reduction of the amount of micropollutants at the point source WWTP effluent will be required to ensure a good chemical status of the receiving surface waters. In some local legislations micropollutants are already indirectly taken into account at present. An indirect measure for the content of (micro)pollutants is the assessment of water toxicity. The analysis of the resulting toxicity of water for Daphnia magna (water flea) has been obligatory in Wallonia since March 2016.
Innovative treatment technologies for elimination of persistent, mobile and/or toxic micropollutants in wastewater are needed. For an effective reduction of micropollutants, traditional WWTPs need additional barriers, such as advanced treatment technologies (tertiary wastewater treatment). In recent years, some wastewater treatment processes (activated carbon, ozonation, UV-oxidation) have been investigated for this reason.
The inquiring path to reduce organic trace substances in wastewater
The aim of the project was to reduce trace organic compounds, often also referred as micropollutants or contaminants of emerging concern (CECs), in wastewater from municipal and industrial treatment plants. A combination of ozonation with photocatalysis and an adsorption step was studied with the aim of eliminating as many micropollutants as possible. First steps in the project were the selection of relevant micropollutants in Belgium and Germany and the identification of the most efficient titanium dioxide (TiO2) coating to increase the efficiency of the photocatalysis step. This was followed by laboratory-scale tests to evaluate the combination process of the oxidative processes. The next step was a scale-up of the TiO2 coating and the development of a treatment process in a mobile container at a wastewater treatment plant. The advantage of a mobile container is the fast and space-saving application on site. The structure and design of the combination process (ozone-UV) is crucial to facilitate future implementation by small or medium sized enterprises (SMEs).
The successful development of a combination module for the oxidative and adsorptive treatment of wastewater in a mobile container
Within the framework of the research project, a combination module for the oxidative and adsorptive treatment of wastewater was successfully developed in a mobile container (Figure 1).
The development of a stable coating based on TiO2 to increase the effectiveness of UV treatment for individual substances could also be demonstrated on a laboratory scale. By combining oxidative and adsorptive processes, a wider range of substances can be eliminated from wastewater. Each process step can be selected individually or for particularly heavily polluted wastewater, a combination of processes can be selected.
This is especially for different industrial wastewaters important. The costs for the combined treatment of a wastewater are significantly higher than the costs for a single treatment step, but significantly lower than the costs for thermal disposal of liquid waste like often done in the chemical or pharmaceutical industry. The re-use idea and thus the resource-saving handling of the foodstuff water is also supported by the use of the wastewater treatment methods. Furthermore, pre-treatments for a more extensive biological degradation by means of oxidative technologies are conceivable.
The economic benefits
As SMEs, both plant manufacturers and distributors of coatings or plant components can benefit from this type of wastewater treatment. The further developed technologies can be applied to municipal and industrial wastewater treatment.
01.09.2017 – 29.02.2020
Dr. Jochen Türk, Institut für Energie- und Umwelttechnik e.V., e-mail: email@example.com,
phone: 02065418 179
Dr. Christelle Vreuls, Celabor, e-mail: Christelle.Vreuls@celabor.be,
phone: +32 87 322 460
Dr. Stephanie Lambert, University of Liège, NCE, e-mail: firstname.lastname@example.org, phone: +32 4 366 4771
Participants from Germany:
IUTA – Institut für Energie- und Umwelttechnik e. V, Duisburg, North Rhine-Westphalia, Germany
Participants from Belgium:
CELABOR, Herve, Wallonia, Belgium – Coordinator
ULG-NCE, University of Liege, Department of Chemical Engineering – Catalysis, Nanomaterials, Electrochemistry, Liege, Wallonia, Belgium
Images: © Institut für Energie- und Umwelttechnik e.V.