| Summary: | 碩士 === 國立屏東科技大學 === 環境工程與科學系所 === 100 === Dissolved organic matter (DOM) originates from widely diverse sources, which affect the distribution, sorption, transport, and biological toxicity of persistent organic pollutants, and play a key role in biogeochemical cycles. Wastes generated by concentrated animal feedlot operations (CAFOs) are rich in DOM. This study investigated the change in pig farm wastewater DOM following different wastewater treatments. The binding capacity to estrogen-like compounds was also studied. In addition, the binding capacity and properties were compared with the different sources of wastewater treatment plant effluent.
In this study, optical indices of UV/Vis and fluorescence spectra were used to characterize the properties of DOM in different wastewater treatment units. The results showed that the humification degree and molecular weight increased in DOM following wastewater treatment. Three municipal and three pig farm effluents were studied. Regarding municipal wastewater treatment plant effluents, the plant “D” municipal effluent had a higher degree of humification than two other plants, plants “F” and “L”. Fluorescence peaks showed a blue shift, which represented a smaller degree of humification. Considering the humification degree of the pig farm effluent, plant “P3” had higher degree humification than plants “P2” and “P1”.
The DOMs were separated into high and low molecular weight solutions (HMWOM and LMWOM, respectively). The HMWOM had a higher degree of humification than the LMWOM in treatment processes that included raw water, an anaerobic process, and an aerobic process but the effluent had different properties in a large pig farm wastewater treatment plant. Different effluent DOMs in a wastewater treatment plant (EfOM), the “D” and “L” plants, and three pig farm effluents, had a higher wavelength and intensity in the HMWOM fluorescence peak than LMWOM.
The investigation of nonylphenol (NP), octylphenol (OP), and bisphenol A (BPA) sorption capacity to DOM with a fluorescence quenching method shows that HMWOM had a better sorption capacity than LMWOM but there were conflicting results in the municipal wastewater effluents. The log Kdoc values ranged from 3.46 to 5.58 for BPA, from 3.87 to 5.73 for OP, and from 2.26 to 5.83 for NP.
FT-IR spectra of the DOM samples in pig farm wastewater in different treatment units showed five samples had a hydroxyl group (OH), a carboxyl bond (O-H), olefins bond (C=C), alkyl, ethers, alcohols and carbohydrates bonds (C-O), and an aromatic bond (C-H). The FT-IR spectra in HMWOM and LMWOM had a similar bonding signal but the LMWOM had a stronger signal than the HMWOM. The correlation analysis showed that indices of Bio/Geo, sum of fluorescence intensity in region IV divided to sum of fluorescence intensity in region V (R4/R5), sum of fluorescence intensity in region III divided to sum of fluorescence intensity in region V (R3/R5), and absorbance integral area from 250 nm to 450 nm (A250) had good correlation with specific ultraviolet absorbance at 254 nm divided DOM carbon concentration (SUVA254). Especially the index of A250; it can be used as alternative parameters of SUVA254, and had a significantly positive correlation with SUVA254, which is a well-established humification index.
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