Engineering and Architecture
Sandra Contreras Iglesias
Marta Schuhmacher Ansuategui
Nanoscience, Materials and Chemical Engineering
Evaluation Of Treatments for the Removal of Microplastics In Urban Wastewater Treatment Plants
Microplastics have become recently a major cause of concern due to their widespread distribution, small size, persistence and uncontrolled introduction into the environment. Wastewater treatment plants (WWTPs) are considered one of the major sources of introduction of microplastics into aquatic environments. Microplastics in municipal wastewater treatment plants have their origin in daily life activities, e.g., laundry processes (polyester and polyamide components), personal care (from the use of toothpaste, shower gel…), medicines or consumer plastics.
Microplastics may pose different problems when present in aquatic environments: aggregation onto cell membrane surface after uptaking, adsorption of pollutants and their introduction into organisms, additives in plastics may be transferred to gut tissues… When present in the environment, they suffer the action of different processes (photodegradation, attrition, biodegradation, oxidation), that may induce changes in the morphology, mechanical properties, molecular weight, surface characteristics. This aging process of microplastics can also change their adsorption properties (Liu et al., 2019).
The efficiency on the removal of microplastics in WWTPs depends on the treatment stages applied. According to previous studies (Liu et al., 2021 and references herein) up to 99% of microplastics entering a WWTP could be removed by the combination of pre-treatment, primary, secondary and tertiary treatment. However, they were primarily transferred to the sludge phase; and still, the large volumes of treated water discharged also involve a significant introduction into the environment. Single technologies have been also studied (grit chambers, biological processes, advanced oxidation processes), but results obtained differ significantly between the different studies.
The objective of this research is to study the performance of different technologies (belonging to primary, secondary and tertiary treatments) in the removal of microplastics and understanding the mechanism of action of these technologies on microplastic parts. A special focus will be given to the application of different advanced oxidation processes (Fenton, ozonation and O3/H2O2, UV/H2O2, photocatalysis) as tertiary treatments. Some previous studies on the application of AOPs to the degradation of microplastics have been published (Gomes et al., 2021; Liu et al., 2019; Tofa et al. 2019).
In the framework of an undergoing doctoral thesis, a methodology for the quantification and characterization of microplastics has been developed. The techniques that will be used in the thesis include the removal of organic matter by advanced oxidation-Fenton, and a combination of alkaline and enzymatic hydrolysis. Subsequently, will be applied a density separation and the particles will be classified and identified using a stereoscopic, optical and electron microscope (SEM) combined with spectroscopy techniques (Raman, ATR-FTIR, µFTIR) (Hurley et al., 2018; Lares et al., 2018; Mahon et al., 2018). According to the concentration of total solids in each treatment unit, different methodologies will be applied to obtain an accurate analysis of the Microplastics.
G. de Aragao Bele T., Neves T.F., Cristale J., Prediger P., Constapel M., Dantas R.F., “Oxidation of microplastics by O3 and O3/H2O2: Surface modification and adsorption capacity”, Journal of Water Process Engineering, 41, 102072 (2021).
Hurley, R. R.; Lusher, A. L.; Olsen, M.; Nizzetto, L. Validation of a Method for Extracting Microplastics from Complex, Organic Rich, Environmental Matrices. Environ. Sci. Technol. 52, 7409− 7417 (2018)
Lares M, Ncibi MC, Sillanpää M, Sillanpää M Occurrence, identification and removal of microplastic particles and fibers in conventional activated sludge process and advanced MBR technology. Water Res 133:236–246 (2018)
Liu P., Qian L., Wang H., Zhan X., Lu K., Gu C., Gao, S. “New insights into the aging behaviour of microplastics accelerated by advanced oxidation processes”, Environ. Sci. Technol., 53, 3579-3588 (2019).
Liu, W., Zhang J., Liu H., Guo X., Zhang X., Yao X., Cao Z, Zhang T., “A review of the removal of microplastics in global wastewater treatment plants: Characteristics and mechanisms”, Environment International, 146, 106277 (2021).
Mahon, A. M.; O’Connell, B.; Healy, M. G.; O’Connor, I.;Officer, R.; Nash, R.; Morrison, L. Microplastics in Sewage Sludge: Effects of Treatment. Environ. Sci. Technol., 51 (2) (2017).
Tofa T.S., Kunjali K.L., Pau S., Dutta J., “Visble light photocatalytic degradation of microplastic residues with zinc oxide nanorods”, Environmental Chemistry Letters, 17, 1341-1346 (2019).
Highly desirable attributes of the ideal candidate
* Hold a Master degree, or equivalent, in: Chemical Engineering or related
* Language skills: Good English level
* Other skills:interpersonal skills, teamwork, able to work in an international and competitive environment, hard working, science-driven
Ethics: This project does not involve ethical aspects
Workplace Location: Campus Sescelades, Tarragona
37.5 hours a week
12 April 2022
|This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 945413|