Occurrence And Removal Of Organic Pollutants In Piggery Wastewater And Its Treatment System

As one of the most important environmental problems to be solved in many countries, piggery wastewater treatment and disposal raise a lot of attention in recent years. Piggery wastewater is a mixture of animal waste and flushing water, with high concentrations of organic matter, suspended solids, ammonia nitrogen and phosphorus, which far exceed the national discharging standards. Moreover, large numbers of toxic or harmful organic compounds existed in piggery wastewater, including conventional pollutants and emerging contaminants, such as lipoid substances including fats, fatty acid compounds and sterol, and odorants including aromatic phenols, nitrogen-containing heterocyclic compounds, volatile fatty acids, thiol, and two inorganic species, NH3 and H2S belong to the former. Some of the especially antibiotics which were belonged to emerging contaminants were also detected in piggery wastewater. These incomplete treated pollutants discharged into lakes, rivers or other water bodies, cause serious pollution of lakes and rivers.According to the previous studies, most of the attention has been paid to the conventional pollutants analyses, such as COD, BOD5, TN and TP. The specific organic components of piggery wastewater are real studied. In the present study, the overall characterization of organic matters of piggery wastewater has been reported, the optimized quantification methods for conventional pollutants and emerging contaminants are well established respectively. Removal effectiveness of these pollutants during wastewater treatment plant in pig farm has been evaluated, paying a special attention to transformation and degradation fate of MLs antibiotics under solar irradiation. The main points of this thesis are summarized as follows:Occurrence and removal of organic components in piggery wastewater. A new pilot-scale wastewater treatment plant containing preliminary treatment, RPAFR, MEOD and MFMI system was introduced. More than 90% pollutants were removed after treatment processes. Piggery wastewater was fractionated by three ways:different molecular size, resin absorption and polarity diversity. Different size fractions were operated by UF system into six parts from 1 kDa to 1μm: M1 (not fractionated), M2 (<1μm), M3 (<0.45μm), M4 (0.45μm～1μxm), M5 (<1 kDa) and M6 (1 kDa～0.45μm). The SUVA values at different wavelengths decreased with increase in UV absorbance:210 nm> 254 nm> 280 nm. The SUVA of different fractions changed in the following way:M5> M4> M6> M2> M3. The FT-IR spectra of organic matters of different fractions (M1-M6) were similar, and nine absorption bands were observed. DOM from sample M3 was fractionated into six fractions:HoA, HoB, HoN, HiA, HiB and HiN. From the UV spectra, the functional peaks appeared at 254 nm and 280 nm. Most of the organic matters were existed in HoA, HoN and HiB fractions. The FT-IR spectrum showed nine main bands. The existence of high concentration of protein and amino acids was revealed, and the P-H stretch was attributed to phosphorous substances. The main non-polar components were alkanes in both M3 and M5 fractions, indicating that non-polar organic pollutants were predominantly alkanes in the DOM fractions of the wastewater. For aromatic component, phenol-like compounds accounted for more than half of the aromatics fractions of organic compounds in sample M3, phthalates acid esters (PAEs) and other non-polar esters accounted for more than 15% of the aromatics compounds in sample M3, and more than 50% in sample M5. For non-hydrocarbons component, sterols and FAMEs accounted for more than 70% of the fractions. In this study, six pharmaceuticals were also identified in non-hydrocarbons fraction of M3 and M5.Occurrence and removal of malodorous substances and long chain fatty acids. The analytical conditions of malodor substance which pre-concentrated by HS-SPME and SPE were optimized respectively. For HS-SPME, the optimal extraction conditions were pH=4,30 min at 70℃, with 30%(m/v) NaCl addition; the desorption process was 3 min at 260℃. For SPE, the best conditions were pH=7, with 30%(m/v) NaCl additon and 10 mL DCM-Hexane (1:2) as eluting solvent. At the best condition, the detection limits ranged from 0.09 to 1.48μg L-1 and the measurement precision was less than 15% of most compounds. The two methodologies were compared in evaluating indicators, such as selectivity, sensitivity and odor quantification. HS-SPME showed better results in terms of LOQs and RSD than SPE, but the semi-validated method of SPE also provide appropriate alternative approaches for qualitative and quantitative analysis of volatile compounds in piggery wastewater. All of the odorants were not completely removed in wastewater treatment plant, the residual toxicity of which was a incipient fault for human health.The analytical method of long chain fatty acids determination is established by XAD resins separation coupled with GC-MS detection. The major fatty acids (considered as a relative percentage of the total) in the wastewater were palmitic acid (C16:0) and stearic acid (C18:0). Stearic acid achieved nearly 1.4 mg L-1 level in the wastewater as one of the saturated acid. Some unsaturated acids (C16:1,C18:1 and C20:1) were also coeluted and observed at relative high concentration. Most of the fatty acids were not well removed in RPAFR system. Nevertheless, more than half of the fatty acids were removed in MEOD system (effluent W2). Nearly all the fatty acids were completely removed after MFMI treatment (effluent W3). The obtained results showed that our pilot scale wastewater treatment process was suitable for fatty acids removal from piggery wastewater.Occurrence and removal of veterinary antibiotics in wastewater treatment processes. An optimized SPE-LC/MS/MS method to analyze multi-residues of selected TCs, SAs, FQs and CAP in groundwater, lake water and swine wastewater was presented. A method for rapid multi-residue screening of PCs using LC-ToF-MS and LC-MS/MS were compared in this chapter. Both of LC-ToF-MS and LC-MS/MS were rapid and simple in PCs analysis, however, LC-MS/MS presented lower limit of detection and high reliability. The concentrations of antibiotics residues in groundwater, lake water, final effluent and influent swine wastewater were respectively 1.6-8.6, 5.7-11.6,7.9-1172.3 and 8.5-21692.7 ng L-1 in summer; and respectively 2.0-7.3,6.7-11.7, 5.8-409.5 and 32.8-11276.6 ng L-1 in winter. AMOX, AZT and ERT were appeared in relative low concentration in effluent wastewater (540 ng L-1,602 ng L-1 and 456 ng L-1, respectively). The LOQ levels were relative rather low in groundwater, lake water, final effluent wastewater and influent wastewater. Even though the antibiotics were detected at relatively low concentrations, there are high risks of their toxic effects on non-target organisms and, finally, on human health.Photodegradation of macrolide antibiotics in the aquatic environment under simulated and natural sunlight irradiation. In order to explore the feasibility of photodegradation of macrolide antibiotics, the photodecomposition kinetics of AZT in six matrices (HPLC water, FW, FW+nitrate, HA, FW+nitrate+HA and piggery wastewater) were studied in photochemical reactor simulating solar irradiation. Photodegradation of AZT followed first-order kinetics in all six matrices with order of degradation rates as follows:FW+nitrate+HA> HA> piggery wastewater> FW+nitrate> FW> HPLC water. A UPLC-(+)ESI-QqToF-MS2 allowed to identify tentative major phototransformation products (TP 1, TP 2, TP 3, TP 4, TP 5, TP 6 and TP 7) of AZT was applied. TP 1 and TP 2 were generated by methyl radical loss from AZT. Further degradation of TP 1 and TP 2 leads to the generation of TP 3 and TP 4 via loss of·O·and methyl radical from two sugars, respectively, and then the formation of TP 5 and TP 6 by loss of desosamine and cladinose sugar from AZT, respectively, wile TP 5 and TP 6 could be degraded directly from AZT by sugar loss. The final product of TP 7 with macrolide ring was considered to be formatted from TP 1-TP 6 or directly from AZT. The optimized mass condition in MRM mode was used for TPs quantification by UPLC-QqQ-MS2. Most of the TP 1, TP 2, TP 3, TP 4 and TP 5 were generated less than 1 hour, and arrived at the highest concentration less than 10 hours in different matrices. While TP 6 and TP 7 were generated at very different time, and the highest concentrations were obtained between 30-50 hours irradiation. However, most of the TPs were detected in the final solution after 70 hours of irradiation. TP 1 and TP 6 persisted more than 100 hours in piggery wastewater under irradiation. The half life of AZT at 5.4 d in river water was obtained, and more than 70% of which was removed after 8 days. Transformation products of TP 1 and TP 6 appeared in half of one day in river water, and were also detected in the final sample under 35 days irradiation. Thus, the environmental risk of AZT and its degradation products need to be gained more attention, and the necessity of investigate the fate of these contaminants was evidenced in order to obtain a realistic estimation of the environmental impact.