可见光催化氧化—生物降解直接耦合技术降解四环素废水的效能与作用机制

发布时间：2018-08-09 19:33

【摘要】：抗生素类废水处理技术高能耗与低效率之间的矛盾是亟待解决的技术难题。目前被广泛采用的高级氧化技术存在处理费用高、矿化不完全的问题。由于抗生素具有杀菌抑菌的特性,生物法不能单独完成抗生素废水的处理。工程上广泛采用高级氧化法和生物降解联合工艺进行抗生素废水处理,其中抗生素的氧化程度是该工艺高效低耗的关键调控因子。光催化氧化-生物降解直接耦合技术(VPCB)与上述传统工艺相比,对抗生素废水处理具有潜在优势。VPCB体系中,可生物降解的光催化中间产物能够被微生物直接利用,避免了过度氧化并提高了矿化效率。然而,目前还鲜见VPCB技术用于降解抗生素类废水的报道,其所涉及到的关键科学问题就是载体内部的生物膜是否能维持活性并发挥生物降解功能。论文选择盐酸四环素(TCH)作为模式污染物,首先探讨了VPCB对TCH降解的效能与机制。以多孔海绵为载体,以银掺杂的二氧化钛为光催化剂,以活性污泥为生物种源,成功的制备了光催化生物降解直接耦合复合载体。与单独的光催化反应(VPC)相比,VPCB对TCH的降解速率提高了10%。光催化反应积累的骈四苯的大分子中间产物能够被VPCB中的生物进一步的降解。生物膜观察和溶解性微生物代谢产物分析(SMPs)结果进一步阐明VPCB载体内部的生物膜未受到显著伤害。VPCB中的生物群落结构演替过程中,耐TCH的菌属(Methylibium)、带有TCH抗性基因的菌属(Runella)、和降解芳香化合物及其衍生物的菌属(Comamonas和Pseudomonas)丰度显著增加。此外,VPCB对TCH的矿化效率较光催化氧化提高了23%。可见,VPCB中生物降解对提高TCH降解速率和矿化效率起到了关键作用。采用外加醋酸盐的手段,探讨进一步提高生物活性对VPCB中TCH降解的影响。外加NaAc后,生物膜中的活菌比例从56%提高至86%,生物膜活性显著提高,VCPB对TCH的降解效率从90%提高至95%,降解速率常数提高了~40%,出水溶解性化学需氧量(SCOD)分别降低了5.2和16.1 mg/L。同时,生物群落结构演替并富集了Thauera、Pseudomonas、Runella等与TCH或其中间产物降解有关的菌属,强化了TCH光催化产生的中间产物的降解。中间产物分析结果进一步揭示投加NaAc后VPCB中产生的一些含π-π共轭体系的小分子中间产物能被微生物进一步降解。这说明基于外加电子供体的策略提高生物活性,不仅能够强化光催化氧化作用,还能有效避免光催化中间产物的累积。论文首次探讨了VPCB在抗生素类废水处理领域的应用,解析了典型抗生素TCH在VPCB中的降解行为和降解途径,发现了生物降解在VPCB技术中的关键作用和自我调节机制,并提出了外加电子供体的策略进一步提高TCH的降解效率和矿化效率。论文研究结果为抗生素废水高效降解提供了新的思路。
[Abstract]:The contradiction between high energy consumption and low efficiency in antibiotic wastewater treatment is an urgent technical problem. The advanced oxidation technology, which is widely used, has the problems of high treatment cost and incomplete mineralization. Because of the bactericidal and bacteriostasis characteristics of antibiotics, the treatment of antibiotic wastewater can not be completed by biological method alone. The combination of advanced oxidation and biodegradation is widely used in the treatment of antibiotic wastewater. The oxidation degree of antibiotics is the key regulation factor of high efficiency and low consumption in this process. Photocatalytic Oxidation-Biodegradation Direct Coupling Technology (VPCB) has potential advantages in antibiotic wastewater treatment. Biodegradable photocatalytic intermediates can be directly utilized by microorganisms. Overoxidation is avoided and mineralization efficiency is improved. However, there are few reports on the application of VPCB technology in the degradation of antibiotic wastewater. The key scientific problem involved is whether the biofilm inside the carrier can maintain its activity and play a biodegradation function. In this paper, tetracycline hydrochloride (TCH) was selected as the model pollutant. Firstly, the effect and mechanism of VPCB on TCH degradation were discussed. Using porous sponge as carrier, silver doped titanium dioxide as photocatalyst and activated sludge as biological provenance, the photocatalytic direct coupling composite carrier for biodegradation was successfully prepared. Compared with the photocatalytic reaction (VPC), the degradation rate of TCH was increased by 10%. The macromolecular intermediates accumulated in photocatalytic reaction of tetrabenzenes can be further degraded by VPCB. Observation of biofilm and analysis of metabolites of dissolved microbes further clarified that biofilm in VPCB carrier had not been significantly damaged. The abundance of (Methylibium), (Methylibium), with TCH resistance gene, and Comamonas and Pseudomonas, which degrade aromatic compounds and their derivatives, increased significantly. In addition, the mineralization efficiency of TCH was increased by 23% than that by photocatalytic oxidation. Therefore, biodegradation plays a key role in improving the degradation rate and mineralization efficiency of TCH. The effect of increasing biological activity on the degradation of TCH in VPCB was studied by adding acetate. After adding NaAc, the proportion of living bacteria in the biofilm increased from 56% to 86%, the bioactivity of biofilm increased significantly from 90% to 95%, the degradation rate constant increased by 40%, and the dissolved chemical oxygen demand (SCOD) in the effluent decreased by 5.2 and 16.1 mg / L, respectively. At the same time, the biocommunity structure succession and enrichment of TCH and other bacteria related to the degradation of TCH or its intermediate products enhanced the degradation of intermediates produced by TCH photocatalysis. The results of intermediate product analysis further revealed that some small molecular intermediates containing 蟺-蟺 conjugated system produced in VPCB after adding NaAc could be further degraded by microorganisms. This indicates that the strategy based on external electron donor can not only enhance the photocatalytic oxidation, but also avoid the accumulation of photocatalytic intermediates. In this paper, the application of VPCB in the treatment of antibiotic wastewater is discussed for the first time. The degradation behavior and pathway of typical antibiotic TCH in VPCB are analyzed, and the key role and self-regulation mechanism of biodegradation in VPCB technology are found. The strategy of external electron donor was proposed to further improve the degradation efficiency and mineralization efficiency of TCH. The results of this paper provide a new idea for the high-efficiency degradation of antibiotic wastewater.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X703

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