Disinfection By-Product Precursor Identification and Formation Potential in a Full-Scale Wastewater Reuse Facility: A Year-Long Study
Date
2023-12-13
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Abstract
Water scarcity is a critical global challenge, prompting the exploration of innovative solutions to ensure sustainable safe drinking water. Wastewater reuse has emerged as a promising approach to address this issue, offering a means to augment water supplies while reducing environmental impacts. This research project investigates the effectiveness of advanced wastewater treatment processes to remove contaminants that form toxic disinfection by-products ( DBPs). Wastewater samples were collected monthly over the course of a year (April 2022-April 2023) after various treatment stages including treated wastewater secondary effluent, ultrafiltration, ultrafiltration followed by ozone, and ultrafiltration followed by reverse osmosis. This investigation also included the characterization of the organic matter through spectroscopy techniques, and the formation potential of six regulated and unregulated DBP families after chlorination and chloramination, which are the two most commonly used disinfectants. To unravel the complex organic matter and obtain detailed monitoring of seasonal changes in wastewater before disinfection fluorescence analysis along with Parallel Factor Analysis was carried out in each type of water. Organic matter characterization further revealed that the main constituents in wastewater are related to three main groups: humic acid like, soluble microbial products like, and aromatic protein like. The concentrations of these groups change over the seasons but are also transformed over the treatment process, especially after ozone. Disinfection was performed on each water sample under uniform formation conditions. To quantify the DBPs present after disinfection gas chromatography and tandem mass spectrometry techniques were employed. The study identified 30 DBPs from six families of DBPs: trihalomethanes, haloacetonitriles, halonitromethanes, haloketones, iodinated trihalomethanes, and haloacetaldehydes. By comparing the results from fluorescence and disinfection analysis, the research established connections between the precursor concentrations and DBPs formed during disinfection, alongside other parameters used to monitor water quality after treatment. Correlations between total precipitation (i.e. snow, rain), nitrate, bromide, and DBP formation potential were found. This project also involved the evaluation of the cytotoxicity and genotoxicity of the treated waters to better understand the potential health risks associated with the presence of DBPs and demonstrate the relevance of nitrogen compounds and the utilization of chloramine in the presence of nitrogen-based DBPs, and in consequence the toxicity related to their occurrence in waters. The results obtained from this approach offer valuable insights into identifying DBP precursors and the overall safety of the disinfected wastewater, providing critical information for decision-makers and water treatment practitioners.
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Keywords
Disinfection by-products, Wastewater rehuse, EEM-PARAFAC, Fluorescence, GC-MS/MS
Citation
Perez Perez, J. A. (2023). Disinfection by-product precursor identification and formation potential in a full-scale wastewater reuse facility: a year-long study (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.