Efficient removal of natural organic matter from drinking water for reducing disinfection by-products
Chlorine as a low-cost bactericide has been used for more than a century for the disinfection of drinking water. However, the contact between chlorine-based disinfectants and natural organic matter (NOM) leads to the production of hazardous disinfection by-products (DBPs). Trihalomethanes (THMs) and...
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| Format: | Thesis |
| Language: | English |
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Memorial University of Newfoundland
2022
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| Online Access: | https://research.library.mun.ca/15868/ https://research.library.mun.ca/15868/1/converted.pdf |
| Summary: | Chlorine as a low-cost bactericide has been used for more than a century for the disinfection of drinking water. However, the contact between chlorine-based disinfectants and natural organic matter (NOM) leads to the production of hazardous disinfection by-products (DBPs). Trihalomethanes (THMs) and haloacetic acids (HAAs) as two groups of regulated DBPs by U.S. EPA and Health Canada have been of concern in the last two decades for the water treatment facilities around the world, specifically small communities of Newfoundland. Enhanced coagulation (EC) and adsorption with activated carbon (AC) are two recommended methods by U.S. EPA for the removal of NOM. Although many studies have tested these methods in full scale and lab scale for the removal of dissolved organic carbon as the main precursor of THMs and HAAs, certain environmental factors in NL (e.g., seasonal variations) and treatment factors (i.e., fast mixing and settling time in EC, and aluminum coating in AC) have not been considered so far. This research aims to (i) examine the effect of five factors of pH, coagulant dosage, coagulant type, fast mixing speed, and settling time simultaneously on the removal of DBPs rather than DOC. (ii) establish prediction models for the removal of DOC and reduction of THMs and HAA5 based on NL water characteristics. (iii) decrease the power consumption of EC. (iv) to reduce the coagulant dosages (v) improve the mesoporosity of activated carbon for NOM removal by chemical activation using nitric acid and physical activation, (vi) enhance the removal of DOC and humic acids by surface charge modification through metal impregnation, (vii) study the efficient removal of NOM by combination of EC and AC (viii) study the variations of NOM characteristics in four communities of NL over two years. (ix) to figure out the most crucial factors affecting the production of HAA5 and THM4. The results of this research on EC confirmed that optimization of EC parameters based on THMs and HAAs reduction, reduced the dosage of coagulant ... |
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