石墨烯类纳米材料对废水生物处理系统的影响和作用机制研究

Because of their unique physical and chemical properties, graphene nanomaterials have been widely applied in many fields, and have a good development prospect Along with the large-scale industrial production and application of graphene nanomaterials, the waste containing such materials will enter the environment. Prospective studies on the environmental impacts and risks of these materials should be done, however, there is little research in this area at present. Regarding the point of graphene nanomaterials flowing into wastewater treatment system, the effects of materials on wastewater biological treatment will be studied in present project in order to provide reference for the evaluation of the effect of graphene nanomaterials on water environment. Taking graphene oxide and activated sludge as research objects and adopting laboratory-scale activated sludge reactor, effects of graphene nanomaterials on wastewater treatment efficiency (including COD, N and P removal efficiency) and sludge dewatering performance will be investigated in present study. Existing states of GO in biological treatment system will be analyzed to explore its distribution patterns in extracellular, intracellular and mixed liquid and to reveal micro-mechanisms of interactions between GO and microorganism. Effects and mechanisms on bacteria activity of different concentration graphene nanomaterials in activated sludge will also be studied by molecular biological means, so as to select the characteristic microorganism which is suitable for the treatment of graphene oxide, and provide proactive solution for environmental issues caused by application of graphene nanomaterials.

石墨烯类纳米材料因其特有的物理化学性质使其在很多领域有着广泛的应用，具有良好的发展前景。伴随着其大规模的工业化生产和应用，含有此类材料的废物必将进入环境，由此带来的环境影响及环境风险需做前瞻性的研究，然而目前此方面研究甚少。本研究拟以石墨烯类纳米材料进入废水系统为切入点，研究其对废水生物处理的影响，以期为石墨烯类纳米材料对水体环境的影响评价提供借鉴。本课题以氧化石墨烯（GO）和活性污泥为研究对象，采用活性污泥法小试生物试验，研究石墨烯类纳米材料对废水处理效果（COD、N、P去除效果）和污泥脱水性能的影响；分析GO在微生物处理系统中的赋存状态，探索其在胞外、胞内及混合液内的分布规律，揭示氧化石墨烯与微生物相互作用的微观机理；应用分子生物学方法分析其浓度对活性污泥中细菌活性影响与作用机制，以期筛选出适宜处理氧化石墨烯的特性微生物，为未来石墨烯类纳米材料可能带来的环境问题提供前瞻性的解决方案。

石墨烯类纳米材料因其特有的物理化学性质使其在很多领域有着广泛的应用，具有良好的发展前景。伴随着其大规模的工业化生产和应用，含有此类材料的废物必将进入环境，由此带来的环境影响及环境风险需做前瞻性的研究，然而目前此方面研究甚少。本研究以氧化石墨烯进入废水系统为切入点，研究了其对废水生物处理的影响。.首先探究了高浓度GO材料泄露进入城市污水处理系统对污水处理系统短期影响，发现160 mg/L的GO使得系统中的COD去除效果降低，240 mg/L的GO使得总氮（TN）的去除性能下降约20%，微生物活性变弱。GO浓度越高活性污泥所受影响越大，GO会激发活性污泥抵御环境变化的能力，但其代谢活性降低，活性污泥的脱氢酶活性随着GO浓度的升高受到的抑制越强，活性污泥的沉降性能变差。.然后考察了进水中浓度不断升高的GO对序批式活性污泥系统的有机物去除、脱氮效果以及微生物群落的影响，在提高GO浓度的试验中，COD、氨和磷酸盐的去除性能下降，低浓度的GO（1-10 mg/L）对氨和磷酸盐的去除性能影响更大。每个浓度梯度下，去除效率都有一定的恢复趋势。.最后对低浓度GO在稳定运行的序批式活性污泥系统中长期存在的情况做了进一步的探索，长期投加低浓度GO会使EPS中多糖的含量最多增加约50%来使其适应GO环境，因而会轻微影响活性污泥的沉降性能。.16S rRNA基因测序的结果表明，长期接触GO会显著改变活性污泥微生物群落的组成和结构，随着GO浓度的增加，细菌的丰富度和均匀度指数均降低。添加GO后观察到细菌群落结构发生了显著变化，然后在不添加GO的恢复阶段稍有恢复。此外，活性污泥中的功能细菌发生了明显变化，并且直接影响系统的氮磷的去除和EPS的产量。.研究还分析了GO进入废水处理系统后，其在系统中的赋存状态，初步探讨了GO的存在对功能微生物的作用机制。以期为石墨烯类纳米材料对水体环境的影响评价提供借鉴。