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Formation Of Anammox Process During Swine Wastewater Treatment And Its Mechanism

Posted on:2022-01-25Degree:MasterType:Thesis
Country:ChinaCandidate:Z Z PanFull Text:PDF
GTID:2491306539970089Subject:Environmental Science and Engineering
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The wastewater from pig production has the characteristics of deep color,more suspended impurities,high organic load and imbalance of carbon nitrogen ratio.How to remove nitrogen efficiently and low consumption is an important research hotspot.Anaerobic ammonium oxidation(anammox)is a recognized green technology with high efficiency and low consumption for microbial removal of inorganic nitrogen.However,the practical application of anammox is still difficult because it is difficult to cultivate anammox bacteria in the actual wastewater environment.This study found that Anammox occurred naturally in some pig wastewater systems in South China,so the mechanism of anammox formation was studied,hoping to provide theoretical support for the popularization and application of anammox technology.In the preliminary investigation of this study,it was found that red granules occurred naturally in several swine wastewater treatment systems in South China.Two swine wastewater systems(named J1 and J2 wastewater systems)in Yangjiang City,Guangdong Province were selected for process analysis and sample collection analysis.In order to verify whether the particles were anammox and the application of anammox process in wastewater treatment system,practical and simulated experiments were carried out,including water quality determination,nitrogen balance,15N isotope tracing,16S r RNA sequencing,antibiotic resistance gene detection and particle observation by focused ion beam microscope(FIB-SEM).These results were as follows:(1)It was found that the red active granules spontaneously formed in the pig wastewater treatment system were indeed anammox granules.The removal rates of NH4+-N and NO2--N by granules(50g)were 18.14 mg N·L-1·h-1and 18.99 mg N·L-1·h-1,respectively.The involvement of anammox process was confirmed by 15N isotope tracing.In addition,anammox bacteria were distributed in the inner,middle and outer layer of the granules.(2)Favorable water quality was one of the reasons for the natural occurrence of anammox.Anammox particles were formed under the DO of 0.19-0.54 mg/L,C/N of 0.60,CODcr<300mg/L,p H of 7.35-7.99.Anammox bacteria became the dominant bacteria under the DO of0.05-1.61 mg/L,C/N of 0.62-2.32,CODcrof 194.7-510.0 mg/L,conductivity of 1.79-6.05m S/cm.(3)Anammox promotes more efficient nitrogen removal,but the effect was related to the condition control.About 99.99%of NH4+-N was removed by first-stage aerobic tank in J1-system,and the residual amount of NH4+-N in effluent was less than 0.02 mg/L.The first-stage facultative tank of J2-system reduced NH4+-N from 561.7 mg/L to 173.6 mg/L under the DO of 0.05±0.01 mg/L and ORP of+81 m V.However,the fitst-stage aerobic tank removal NH4+-N by 170.1 mg/L,but NO3--N was increased by 124.6 mg/L under the DO of 1.21±0.20 mg/L and ORP of+130 m V.(4)Good microbial ecology was one of the important reasons for the natural occurrence and stabilization of anammox.Candidatus Brocadia was the main anammox bacteria in the sludge of the two wastewater treatment systems.Correlation analysis showed that there was a strong positive effect between bacteria.Thermomonas,Arenimonas,Dokdonella and Thiobacillus were the most active with Candidatus Brocadia within nitrogen removal bacteria.Meanwhile,Candidatus Brocadia had the highest correlation with Arenimonas and Dokdonella(about 0.7).(5)The antibiotic resistance gene levels of the two systems are similar to or lower than those of other researchers.The relative abundance of tet A,tet B and tet E were 5.0×10-3 to9.1×10-1,1.23×10-6 to 1.79×10-2 and 5.46×10-8 to 9.48×10-4,respectively.The relative abundances of bla MOX and bla FOX were 6.62×10-9 to 2.82×10-5 and 4.67×10-6 to 2.48×10-3,respectively.
Keywords/Search Tags:anaerobic ammonium oxidation (anammox), swine wastewater, wastewater treatment plant, simultaneous nitrogen removal, antibiotic resistance genes (ARGs)
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