Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Chemical and Biochemical Engineering

Supervisor

Dr. Madhumita B. Ray

2nd Supervisor

Dr. Lars Rehmann

Joint Supervisor

Abstract

Presence of micropollutants in water is a global concern because of their ability to potentially cause adverse effects in organisms at concentrations as low as a few ng/L, particularly when present as a component of complex mixture. Most of the endocrine disrupting compounds (EDC) and pharmaceutical and personal care products (PPCP) are not removed well in traditional wastewater treatment processes and enter the environment and spread throughout the water ecosystem. Depending on the properties of the micropollutants and the biology of the receiving species, they may bioaccumulate, metabolize or cause adverse effects. These effects may translate into alterations on a higher biological level such as disruption of the hormone system, followed by impacts on reproduction, etc. Eventually, effects may translate into other compartments of the ecosystem. Advance oxidation treatment is a powerful technology for the treatment of water and wastewater contaminants. They are characterized by the production of highly reactive and non-selective hydroxyl radicals, and by mineralization of refractory pollutants. However, complete mineralization of organic contaminants is expensive, while partial mineralization may not produce desirable water quality both for ecosystem as well as for potable purposes. All these technologies require an efficient and powerful set of tools and assays in order to quantify the biological compatibility of treated water contaminated with micropollutants. Therefore, bioassays which are powerful tools can be used to screen the estrogencity and the toxicity of a complex chemical mixture.In this work, a full factorial design was applied to investigate the antagonistic-synergistic interactions of different concentrations and mixtures of the model compounds; 17-β estradiol, sulfamethoxazole and bisphenol A and humic Acid. The estrogenic activity was determined by using the yeast estrogencity screen (YES) assay, and the genotoxicity of the compounds and their intermediates was monitored by using the Ames test, before and after ozonation, UV/ O3and UV/ H2O2 which are very effective oxidative treatments for the degradation of various organic micropollutants in water. SMX showed ~ 100% removal in all the AOPs, the slowest removal occurred for only ozonation whereas the combination of UV with ozone and hydrogen peroxide produced much faster degradation rate. While E2 showed much higher degradation in ozonation and combination of UV increased the rate only by 18%. BPA also showed good removal with ozonation, and the rate was increased by only 5% by the addition of UV with ozone. On the contrary, by the addition of H2O2, rate was reduced by 86% from that of UV/ozonation. Humic acid demonstrated the lowest degradation rate of all the compounds tested. The effect of the presence of humic acid on the degradation rate constant of pure compounds and mixtures varied depending on the micropollutants type and the mixture. TOC removal was reduced when HA was added to all solutions.

Humic acid and sulfamethoxazole had a synergistic interaction with 17-β estradiol that led to increase the estrogencity of water by 4.4, 2.7 and 4.7 times for HA- E2, SMX- E2 and SMX- HA- E2 mixtures, respectively both before and during oxidation. No mutagenicity was shown by using the Ames test for all mixtures.

The work demonstrated that bioassays such as estrogencity and mutagenicity and total organic carbon (TOC) reduction can be used to determine the optimum AOP treatment without conducting detailed chemical analyses.


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