Wastewater Treatment From Pharmaceutical Substances With Filamentous Fungi
Summary of the Doctoral Thesis
Brigita Daļecka, Riga Technical University, Latvia; KTH Royal Institute of Technology, Sweden
The ever-increasing concern about the widespread occurrence of pharmaceutical substances in the aquatic environment has been recognized as an emerging environmental issue, as it can cause undesirable effects on the ecosystem and human health. The current wastewater treatment methods are not designed to treat municipal wastewater from the contamination of various pharmaceutical substances. As a result, pharmaceuticals can enter the environment and pose a threat to life forms. Therefore, it is important to enhance the classical wastewater treatment process in order to meet the challenges by advancing the technologies. Currently, the biological treatment method with filamentous fungi has been considered a promising, cost-effective, and environmentally friendly method for removing pharmaceutical substances from municipal wastewater.
Thesis “Wastewater Treatment from Pharmaceutical Substances with Filamentous Fungi” demonstrates the potential application of fungi in removing pharmaceutical substances and their expedience to incorporate into the classical municipal wastewater treatment process. The investigation focused on selecting suitable fungal strains that could adapt without adjusting physico-chemical parameters and compete with the microbial community in the municipal wastewater. Further, the Thesis investigated whether fungal strains could reduce nutrients and pharmaceutical substances in lab-scale and pilot-scale setup and the mechanisms of pharmaceutical substance removal.
The research consists of two main stages. In the first stage, the batch-scale experiments were carried out under laboratory conditions, finding out the most suitable fungal strains for the removal of pharmaceutical substances from wastewater. The results demonstrated that fungi compete with each other, since higher removal efficiency was observed if the fungi were grown individually. Batch-scale experiments showed that Trametes versicolor (a laboratory strain) and Aspergillus luchuensis (an environmental isolate from a municipal wastewater treatment plant) can be promising strains for removing pharmaceutical substances in a non-sterile municipal wastewater treatment without the adjustment of pH level. Therefore, these strains were used for further study.
In the second stage, the pilot-scale system with a fungal fluidized bed pelleted bioreactor was developed. The results demonstrated a high potential to remove phosphorus from municipal wastewater efficiently and successfully under a batch scale experiment with non-sterile municipal wastewater, while the results from the fluidized bed bioreactor did not demonstrate any significant decrease of phosphorus. Additionally, the fluidized pelleted bioreactor was optimized to perceive bioaugmentation as a strategy with the frequent addition of fungal biomass. The results from the optimization process showed that bioaugmentation is a relatively efficient approach to build on fungi in the fluidized pelleted bioreactor. Furthermore, the results from the AI-based platform with modeling study showed that optimization of bioaugmentation with fungi increases the removal efficiency of pharmaceutical substances from non-sterile municipal wastewater.
The author of this study showed that both the literature review and the results from the batch and pilot-scale experiments provided new knowledge that can be used for future investigations of wastewater treatment with fungi. The Thesis will help to improve and better understand the possible application of fungi in the municipal wastewater treatment process.