【作者】 黄辉；

【导师】 任洪强；

【作者基本信息】 南京大学 ， 环境科学与工程， 2015， 博士

【摘要】 生物膜工艺具有高有机负荷、高有机物去除率、低剩余污泥产量、运行管理方便等优点,在未来污水处理“提标增效”、“节能降耗”的要求中,将引发新一轮需求热潮。本研究针对污水处理生物膜法中成膜机理不清、定量评价机制缺乏等问题,以典型污水处理系统和实际工程填料(固定和悬浮式)为研究对象,深入研究了生物膜的形成机制和基于分子水平、生物群落和细菌种群等三个尺度响应生物膜活性的基本规律。研究结果可为生物膜法污水处理工艺的高效稳定运行提供理论指导,并为实现生物膜相关过程的高效调控提供技术支撑。本研究选取生活污水、精细化工废水和化工园区综合废水等3种实际废水,并以此为依据设计12种不同有机污染、盐度特性和离子组成配置组合的模拟废水;选取典型填料材质——聚苯乙烯和聚酰胺,采用石英晶体微天平检测技术,系统研究了填料亲疏水性和水质特征对填料表面薄膜形成过程的综合影响;在此基础上,设计开展典型污水水质条件下固定和悬浮式填料表面生物膜形成及其活性研究;运用磷脂脂肪酸(PLFA)分析技术,解析生物膜在分子水平和生物群落的分布特征,建立生物标志物/群落与生物膜活性的定量关系式;进一步运用16S rRNA高通量测序技术,对生物膜细菌种群及其分布进行鉴定,深入研究细菌种群对生物膜活性的响应规律。论文的总体结论如下:1、关于生物膜的形成(1)填料亲疏水性对生物膜的形成具有显著影响。亲水性表面更利于水溶性污染物的沉积和薄膜的形成,从而加快生物膜的形成。(2)水质特征对薄膜和生物膜的形成具有重要且复杂的影响。有机物浓度越高,薄膜越易形成,且其影响要高于离子及其强度。Ca2+对薄膜形成的影响与离子强度有关,表现为“低促高抑”,即在低离子强度下促进薄膜形成,而在高离子强度下抑制薄膜形成。高盐度有利于生物膜的快速形成,对于同一类型的污水,高悬浮污泥浓度也能显著提高挂膜速度。(3)对填料表面薄膜形成机理的研究表明,大分子的沉积不仅受压缩双电层作用控制,而且还受非DLVO过程的综合影响。(4)采用石英晶体微天平监测污(废)水中溶解性污染物在不同有机填料基质表面的微观沉积,可快速判定填料的生物亲和性。2、关于生物膜的活性(1)生物膜STOUR、SHOUR、ATP/VS和AEC四种活性指标间均呈现极显著正相关性;本研究提出,当AEC小于0.6时,生物膜处于老化状态,需要进行活化。(2)填料类型对生物膜的活性有重要影响。软性和组合填料生物膜更易变成“粘泥”而老化,时间约为60天;在同一水质条件下,悬浮填料生物膜STOUR、SHOUR、ATP/VS和AEC均高于软性和组合填料生物膜,其老化速率较慢,一般需要70天以上。(3)生物膜的活性受污水有机物浓度影响较大,氮、磷次之,并与系统中悬浮污泥活性密切相关。实验条件下,高盐度和有机物含量、高悬浮污泥浓度可加快生物膜老化进程。(4)基于PLFA的分析表明,不同来源生物膜PLFA中,C16:00、C18:00、C16:1 w7c、C18:1 w7c、C12:00和C18:1 w9c是相对丰度最高的6种标志物;生物膜中细菌相对丰度最高,而革兰氏阴性菌相对丰度又显著高于革兰氏阳性菌;真菌含量一般大于放线菌和原生动物;C16:00对STOUR的量化响应最为理想,复合、生长或指数曲线方程为最优模型;真菌对AEC的量化响应最为理想,三次曲线方程为最优模型;老化生物膜真菌等真核微生物含量增加;高有机污染废水生物膜中,真菌等真核微生物含量相对较低;老化组合填料生物膜中革兰氏阳性菌和放线菌含量相对较高。(5)16S rRNA高通量测序结果表明,生物膜中相对丰度较高的细菌主要有变形菌、拟杆菌、放线菌、酸杆菌和厚壁菌;进水水质对生物膜细菌种群的影响大于填料类型,高有机污染高盐度废水生物膜中易富集α-变形菌,而高溶解氧高悬浮污泥浓度体系生物膜中γ-变形菌为优势种群;产生生物膜活性的属水平细菌主要有:动胶菌属、不动杆菌属、Dechloromonas、硝化螺菌属等,与生物膜活性呈负相关的细菌主要包括:暖绳菌属、束缚杆菌属、大理石雕菌属、陶厄氏菌属和特吕珀菌属等;软性和组合填料生物膜老化时,暖绳菌属含量相对较高;悬浮填料生物膜老化时,除暖绳菌属外,不动杆菌属含量也较高。更多还原

【Abstract】 Biofilm process has several advantages such as high organic load,high removal rate of organics,low yield of residual sludge,and convenient operation and management,and is bound to get more application under the demand of standard-raising,efficiency-improving,energy-saving and cost-reducing,upon wastewater treatment in the future.Based on the current situation of insufficient research on microcosmic mechanism of biofilm formation and biotic response to biofilm activity,this study focused on typical wastewater treatment systems and engineered biocarriers(i.e.fixed and suspended biocarriers),and conducted an intensive exploration on the mechanism of biofilm formation and characteristics of responses to biofilm activity by macromolecules,biotic population and bacterial communities.This study is believed to provide theoretical guidance for the stable and highly efficient operation of biofilm wastewater treatment process and can be a technical support for the realization of efficient regulation of biofilm-related processes.Three real wastewater samples containing municipal wastewater,fine chemical wastewater and chemical industrial park wastewater,and twelve corresponding synthetic wastewater samples with different configurations of organics,ion strength and calcium ion(Ca2+),were both employed.Typical biocarriers of polystyrene and polyamide were selected.The comprehensive effect of biocarrier wettability and water quality characteristics on adlayer formation on the surface of biocarriers,was systematically studied,by using Quartz crystal microbalance with dissipation monitoring(QCM-D).On this basis,biofilm formation on engineered fixed and suspended biocarriers and their activities in typical wastewater treatment systems,were investigated.Distribution of biofilm in molecular and biocoenotic levels were analyzed through phospholipid fatty acid(PLFA)analysis,and quantitative relationships between biomarkers/biotic communities and biofilm activity,were established.16S rRNA high-throughput sequencing technology was further adopted to identify bacterial communities and their distributions in biofilm,and the response of bacterial communities to biofilm activity was studied.The overall conclusions of the study were as follows:1.Conclusions on biofilm formation(1)Wettability of biocarriers has a significant influence on biofilm formation.The hydrophilic surface is more conducive to the deposition of water soluble pollutants and adlayer formation and thereby accelerates the formation of biofilm.(2)Water quality exhibits important and complex influences on the formations of adlayer and the biofilm.The higher the organic concentration,the easier the formation of adlayer,with a greater effect than that of the ion and its strength.The effect of Ca2+on adlayer formation is related to the ionic strength,i.e.promoting at a low ionic strength and inhibiting at a high ionic strength,respectively.A high salinity is favorable to the rapid formation of biofilm,for the same type of wastewater,a high concentration of suspended sludge can also significantly improve biofilm retention.(3)The mechanism of adlayer formation on biocarrier surfaces showed that the deposition of macromolecules is not only controlled by the effect of double layer compression,but also by the non DLVO processes.(4)The method that monitoring microcosmic deposition of water soluble contaminants on organic biocarrier surfaces through QCM-D,provides a rapid determination of bioaffinity of biocarriers and has a widespread application prospect.2.Conclusions on biofilm activity(1)Highly significant positive correlations are found among four biofilm activity indexes of STOUR,SHOUR,ATP/VS and AEC.It’s proposed in this study that aging biofilm occurs when AEC is less than 0.6 and further activation is needed.(2)The type of biocarriers has an important influence on biofilm activity.Biofilms on soft and integrated biocarriers are more likely to become "slime" and the aging time is about 60 days.Under the same condition of water quality,STOUR,SHOUR,ATP/VS and AEC of biofilm on suspended biocarrier are higher than those on soft and integrated biocarriers,with a longer aging time of more than 70 days in general.(3)The activity of biofilm is greatly influenced by organic concentration,and secondly the nitrogen and phosphorus,and is closely related to the activity of suspended sludge in the system.Aging process of biofilm can be accelerated by high salinity and organic contents,and the concentration of suspended sludge,under tested conditions.(4)PLFA analysis showed that C16:00,C18:00,C16:1,w7c,C18:I,w7c,C12:00 and C18:1 w9c are the top six biomarkers with highest relative abundance among different sources of samples.Bacteria possesses the highest relative abundance in biotic population,among which a significantly greater amount of Gram-negative bacteria than that of Gram-positive bacteria is observed.The content of fungi is generally greater than that of actinomycetes and protozoa.C16:00 achieves the optimal quantitative response to STOUR,with the best model of compound,growth or exponential curves.Fungi gets the optimal quantitative response to AEC,with the best model of cubic curve.PLFA composition changes in aging biofilm,with the appearance of more microeucaryotes including fungi.The content of microeucaryotes is relatively lower in biofilm living in high organic wastewater.More Gram-positive bacteria and actinomycetes occur in aging biofilm on integrated biocarrier.(5)16S rRNA high-throughput sequencing results showed that the main bacteria with relatively high abundance in biofilm are Proteobacteria,Bacteroidetes,Actinobacteria,Acidobacteria and Firmicutes.Influent quality has a greater impact on bacterial community than that of the type of biocarrier,with enrichment of Alphaproteobacteria in biofilm living in high organic and saline wastewater and Gammaproteobacteria in biofilm living in high dissolved oxygen and concentration of suspended sludge,respectively.Biofilm activity can be promoted by the following bacteria in genus level:Zoogloea,Acinetobacter,Dechloromonas and Nitrospira,and is negatively related to the bacteria mainly including Coldilinea,Haliscomenobacter,Marmoricola,Thauera and Truepera.The content of Caldilinea is relatively high in aging biofilm on soft and integrated biocarriers,while Acin.etobacter is also higher in content in addition to Caldilinea,in aging biofilm on suspended biocarrier.更多还原