| Summary: | 碩士 === 國立屏東科技大學 === 環境工程與科學系所 === 106 === Livestock wastewater, including swine wastewater from animal husbandry has long been concerned for high organic and suspended solid pollutants which need to be properly treated before discharge to avoid environmental pollution. In this study, we investigated the feasibility of using an atmospheric plasma (AP) advanced oxidation process (AOP) to remove organic pollutants from swine wastewater. We explored the better operating condition of this process through testing various operating parameters (plasma power, air flowrate, water volume, and COD/NH3-N loading). Tetracycline (TC), one of environmental emerging contaminants and the most commonly used antibiotics to animal agriculture, is often found in livestock wastewater. Therefore, this study used the obtained better AP operating condition for the degradation of organic pollutants in swine wastewater and prepared solutions to explore the degradation efficiencies of organic pollutants and reaction kinetic parameters. Moreover, fluorescence excitation-emission matrix (EEM) and Ultraviolet-Visible (UV-Vis) tests were conducted to evaluate the plasma-degradation characteristics of water matrices during operations. Liquid chromatography-mass spectrometry (LC-MS), and high performance liquid chromatography (HPLC), analyses were performed to identify the intermediates (products) and pathways of TC plasma-degradation.
The results show that good COD and ammonium nitrogen degradation efficiencies of swine wastewater were achieved by using the better operating condition (plasma power (156 W), air flow (5 L/min), different volumes (250 mL), and temperature (25°C)). After plasma-degradation for 8 hours, the removal rates of TOC, COD, BOD, and NH3-N were 47%-100%, 52%-92%, 55%-95%, and 45%-99%, respectively. The concentration of nitrite nitrogen in most of the wastewater samples increased first and then decreased, while that of nitrate nitrogen increased with increasing operation time.
In the prepared solution, the TC degradation efficiency and TOC removal rate increased with the increase of plasma-degradation time. After 240 minutes, the concentration of TC decreased to ND, but that of TOC did not. The removal efficiencies of TOC, COD, BOD, and NH3-N were 79%-92%, 52%-92%, 40%-95%, and 45%-100%, respectively. The absorption peaks detected in UV-vis analysis for the swine wastewater samples with/without TC addition and prepared TC solution exhibited decreasing intensity and finally disappeared as the electrolysis time increased. Only the prepared TC solution had a new absorption peak and its intensity increased with increasing plasma-degradation time.
In fluorescence analysis, each swine wastewater showed fluorescence peaks in region I (tyrosine-like)/region II (tryptophan-like) and region IV (soluble microbial by-product), respectively, while the prepared TC solution had a fluorescence peak across the region III (fulvic acid-like), region IV (soluble microbial by-product), and region V (humic acid-like). However, the intensities of fluorescence peaks in swine wastewater decreased but that of TC prepared solution increased with the increase of operation time. The TC in prepared solution was degraded by plasma into the intermediates with m/z = 427, 409, 460, 443, 399, 476, 459, 415, 425, 441, 431, 382, 490, 508, 446, 479, 495, 411, 426, 417(1) and 417(2).
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