Enhanced Degradation Of Reactive Red X-3B By Using AQS-PUF/Shewanella Sp. RQs-106/iron

Azo dyes are widely used in various aspects of life and manufacture,thus,the discharge of wastewater containing azo dyes receives people's attention.Azo dyes not only have toxicity,but also their reduction products are of mutagenicity,carcinogenicity and teratogenicity.One of traditional methods for treating azo dyes is anaerobic-aerobic treatment.However,the metabolism rate of anaerobic microorganisms is very slow,and the reduced aromatic amines easily occur auto-oxidation,resulting in the formation of refractory compounds under aerobic conditions.Based on this,in this dissertation,Reactive Red X-3B was used as a model pollutant,the enhanced decolorization performance of Reactive Red X-3B by using AQS-modified polyurethane foam?AQS-PUF?and Shewanella sp.RQs-106was investigated in an up-flow anaerobic sludge bioreactor?UASB?,and the degradation of aromatic amines by AQS-PUF coupling strain RQs-106-driven Fenton reaction was explored.AQS-PUF and strain RQs-106 were used to enhance the performance of UASB treating Reactive Red X-3B.First,AQS-PUF was prepared,on which AQS concentration was 0.0475mmol·g^-1 PUF.Then 2.60 g AQS-PUF was added into the UASB.When hydraulic retention time was 15 h,reflux was 10 mL·min^-1 and the influent concentration of Reactive Red X-3B was 300 mg·L^-1,AQS-PUF and strain RQs-106-supplemented reactor displayed over 88.3%color removal efficiency in 40 days,which increased 6.7%and 17.5%compared with PUF and AQS-PUF-supplemented reactors,respectively.High performance liquid chromatography?HPLC?-mass spectrum analysis showed that Reactive Red X-3B could be anaerobically transformed to aniline and 2-amino-8-?4,6-dichloro-[1,3,5]-trianzin-2-ylamino?-1-naphthol-3,6-disulfonate sodium?ADCTNDS?.Further analysis found that AQS-PUF could promote the secretion of flavins by microorganisms in UASB.The content of total flavins was 58.32nmol·L^-1 in AQS-PUF and strain RQs-106-supplemented reactor,which was 2.7-fold higher than that in AQS-PUF-supplemented reactor.This result showed that strain RQs-106 could secrete more flavins compared with other microorganisms in the reactor,resulted in the enhanced decolorization.Catalytic performance of AQS-PUF in reactors after its long-term usage was slightly lower compared with unused AQS-PUF.High-throughput sequencing analysis showed that the addition of AQS-PUF increased the diversity of the community in reactors.Moreover,genera Clostridium,Bacillus,Pseudomonas,Lactococcus,Geobacter and Shewanella capable of secreting flavins and reducing quinone compounds were enriched.Genus Shewanella became a dominant community due to the addition of strain RQs-106.These studies showed that the addition of AQS-PUF and strain RQs-106 could accelerate the decolorization of Reactive Red X-3B.AQS-PUF coupling strain RQs-106-driven Fenton reaction was explored to degrade aromatic amines.H₂O₂ was prepared via anaerobic bioreduction-aerobic autooxidation circles of AQS-PUF whereas Fe²⁺was produced through AQS-PUF-mediated bioreduction of citrate-Fe.The optimal reaction conditions were 0.20 mmol·L^-1 immobilized AQS,0.16 g·L^-1biomass,40 mmol·L^-1 sodium lactate and 4.5 mmol·L^-1 citrate-Fe.The generated H₂O₂reached 42.9?mol·L^-1 and the removal efficiencies were 48.6%?aniline?and 43.3%?ADCTNDS?,after 7 anaerobic-aerobic cycles.The structure of AQS-PUF analyzed by Fourier transform infrared spectroscopy was negligibly destroyed.HPLC analysis showed that aniline was transformed to p-benzoquinone and phenol,then further degraded into small molecular organics,and finally to CO₂.