Occurrence of organic micropollutants (OMPs) in aquatic environment is a worldwide concern. A long list of anthropogenic substances, including pharmaceuticals, hormones, etc., are frequently detected in natural water sources. Wastewater treatment plants are one main source of OMPs pollution, but also a key step to control OMPs dissemination into the environment. This dissertation focuses on the evaluation of Membrane Aerated Biofilm Reactor (MABR) as a sustainable process to treat wastewater polluted by OMPs. Furthermore, application of high intensity pulsed light is proposed as an innovative tertiary treatment to produce reclaimed water of high quality.
In Chapter 1, a literature review was performed to investigate the occurrence and toxicity of 12 selected organic micropollutants (OMPs) in surface and ground water and the limitations of current available biological processes. Among these technologies, systems with enriched nitrifying activity were able to enhance the removal of specific OMPs through cometabolic activities. Thus, I proposed the use of a MABR with enriched nitrifying biomass to treat OMP polluted water.
In Chapter 2, I studied the influence of biofilm thickness on the removal of 13 OMPs via MABR. Results demonstrated OMP removal was dependent on biofilm thickness and bacterial cell density.
MABR demonstrated important efficiencies in the removal of ammonium, COD, acetaminophen and triclosan at early stages of biofilm thickness. However, the removal of nonpolar, hydrophobic 4
OMPs and anionic, acidic OMPs required thicker biofilms, achieving maximum removal at biofilm with 1.02 mm thickness and 2.2 × 106 cell mL-1.
In Chapter 3, the contribution of sorption and biodegradation in the removal of OMPs via MABR was evaluated. At three stages of biofilm thickness studied, biodegradation dominated the removal for most OMPs. Heterotrophs played an important role in OMP biodegradation at all biofilm thickness, while autotrophic nitrifiers enhanced their contribution at thickness beyond 0.58 mm.
Increased removal of pollutants like estrone and ethinyl estradiol were linked to the MABR enrichment with nitrifying bacteria. Sorption was essential for the removal of lipophilic and recalcitrant pollutants like triclosan.
Finally, to provide high quality treated water for reuse, Chapter 4 explores the use of high-intensity pulsed light (HIPL) as post-treatment. The number of pulses and optical energy dose have a significant impact on the OMPs removal. HIPL demonstrated fast kinetics and efficient photodegradation – with significant OMPs removal within milliseconds.
The findings from my Ph.D. dissertation indicate that MABR combined with high-intensity pulse light may be an effective treatment train for the efficient removal OMPs present in municipal wastewaters. This combined treatment process could potentially pave the way to produce high quality reclaimed water for various reuse purposes.
|Date of Award||Nov 2022|
|Original language||English (US)|
- Biological, Environmental Sciences and Engineering
|Supervisor||Peiying Hong (Supervisor)|
- Biofilm processes
- Biofilm thickness
- Biofilm microbial community
- Organic micropollutants
- Aerobic wastewater treatment
- Degradation Pathway
- High intensity pulse light
- Advanced oxidation processes
- Photonic curing