某厂清水池壁细菌生长特性研究

附着在清水池壁生长的生物膜可能使出厂水的细菌数增加,对饮用水的安全性造成威胁。以北京市某水厂清水池壁上自然生成的生物膜为样本,研究了构成该生物膜的微生物种类,形成了比较系统的菌种鉴定方法。研究发现清水池壁的生物膜中存在细菌、放线菌、真菌和酵母菌等多种微生物,这些微生物以革兰氏染色阳性菌为主。这是因为革兰氏阳性菌细胞壁和细胞膜的通透性比较低,不易被消毒剂杀灭,而革兰氏阴性菌的细胞壁和细胞膜的通透性比较高,消毒剂容易透过细胞壁和细胞膜把细菌杀灭。     

金属给水管道生物膜的形成与控制

金属管道在我国给水管网系统中广泛使用,腐蚀问题增加了金属管道的使用成本。微生物腐蚀是管道腐蚀产生的重要原因。而管壁生物膜是给水管网系统中微生物的主要来源,并带来许多公共卫生问题。重点论述金属给水管道生物膜的形成特点,以及由生物膜的形成带来的生物膜脱落、消毒副产物(DBPs)生成、管道腐蚀等危害。总结影响金属给水管道生物膜形成的因素,在此基础上讨论实际可行的控制策略。最后,从监测和遏制管道生物膜形成等方面做出了展望。     

给水管壁腐蚀对余氯衰减的影响

在参与供水管网余氯消耗的三种因素中,除了主体水和管壁生物膜的消耗外,管壁腐蚀也是不容忽视的因素,尤其在铸铁管中.从微观电化学反应的角度,得到了管壁腐蚀导致的余氯衰减模型,结果与实际情况符合较好.     

管材、营养元素和温度对模拟给水管网生物膜形成的影响

以环状反应器(annular reactor,AR)模拟实际给水管网,研究了管材、营养元素和环境温度对管网生物膜生长的影响。结果表明,4种管材按单位面积最大细菌数,铸铁片铜片PVC片铝片,都超过103CFU/cm2;按生物膜发育成熟速度,铸铁片≈铜片PVC片铝片,成熟时间至少需要一周。在考虑消毒和成本多种因素后,PVC是一种较为理想的管材。增加进水中碳、氮、磷等营养元素的浓度,都会增加模拟管网反应器中的生物膜生物量,且磷对生物膜的影响最大。温度在20～30℃时最适于生物膜的生长,超过或低于这一温度都会抑制生物膜的生长,且低温的抑制作用更为明显。     

模拟输配水系统中化合氯衰减模型研究

通过模拟输配水系统和主体水烧杯试验模拟化合氯的衰减过程,考察了水温、pH、初始氯浓度以及水力流速等因素对化合氯衰减的影响.结果表明:管壁对化合氯衰减影响的速率常数kt远大于主体水化合氯自身的衰减速率常数kb.流速、水温与衰减系数成正比,pH、初始氯浓度与衰减系数成反比,同时建立了化合氯衰减速率常数与上述各因素的数学模型.同时发现,管道细菌繁殖和生物膜增长对化合氯衰减有重要影响,为提高管网水质,管道应定期清洗、消毒.     

可同化有机碳及氯浓度对给水管网中生物膜生长的影响

以北京市自来水集团有限责任公司第九水厂炭滤池出水为研究对象,通过中试规模的臭氧活性炭工艺控制和改变进入模拟管网水中的可同化有机碳(Assimilable Organic Carbon,AOC)及余氯浓度,确定AOC含量、余氯与给水管壁生物膜生长的定量关系.试验表明:AOC浓度对管网中生物膜的生长有显著的影响,在不加氯的条件下模拟管网进水AOC维持在100 μg/L左右时,模拟管网中挂片生物量达到107 CFU/cm2量级;在进水AOC维持在40～50 μg/L时,挂片生物量下降显著,维持在104CFU/cm2量级.在加氯后挂片生物量不超过103 CFU/cm2量级,在余氯0.3～0.5 mg/L下挂片生物量稳定在102 CFU/cm2量级,同不加氯时相比生物膜的生长得到很好的抑制.     

循环冷却水输水管壁生物膜生长发育及微生物腐蚀问题研究

开发设计了一种模拟输水管道生物膜反应器(SIBR)试验装置,该试验装置通过模拟一定输水条件下的管壁剪切力,实现了对输水管网水力特性的模拟,并获得国家专利。应用SIBR反应器模拟了循环冷却水输水管道中的水力条件,研究了以碳钢作为循环水输水管材时管内壁生物膜生长发育状况,探讨了微生物腐蚀机理,并采用X射线衍射技术对管壁腐蚀产物进行了分析。     

多级AO生物膜反应器污泥减量机理研究

在反应器内投加球形多孔微生物载体构建的多级AO生物膜反应器可确保脱氮效果并有效减少剩余污泥产量,以生活污水为试验进水,比传统活性污泥法降低污泥产量90%。反应器污泥减量主要有3方面原因:一是球形多孔微生物载体延长生物膜污泥龄强化生物捕食作用;二是多级AO生物膜反应器内进行多级水解酸化强化微生物隐性增长;三是反应器提供的多级氧化还原环境使微生物的分解和合成代谢相对分离,污泥产率降低。     

饮用水系统生物膜形成和控制研究

饮用水系统生物膜形成和控制是当前研究的热点。系统阐述了饮用水系统中生物膜的形成和影响成膜的各种因素。生物膜控制技术包括降低有机物含量、物理方法、消毒剂、酶试剂控制、分散剂、紫外线消毒等。饮用水系统中生物膜对剥离剂和紫外线具有抗剥离能力,500mg/L的常规剥离剂也难以剥离成熟的生物膜,紫外线对生物膜中微生物杀灭能力明显弱于对溶液中微生物的杀灭作用。采样结果表明:饮用水管道内部存在严重的微生物污染。一旦生物膜形成,其将紧紧附着于管道内壁。控制饮用水系统中生物膜,降低微生物安全风险,对保证安全供水将具有重要的意义。     

天津市给水管网余氯衰减模型研究

以天津给水管网为对象,利用水体自身的信息,通过实验室试验和现场实测,分别确定了主体水和管壁水余氯衰减的模型。结果表明,管壁生长环是影响余氯衰减的主要因素,不同的管道属性对余氯衰减的影响也有较大差别。建立了天津市管网余氯衰减的数学模型。     

反冲洗回收水消毒对除铁锰效果影响生产性试验研究

针对高升水厂在生产运行中出现的除锰效果变差的问题进行了理论分析和生产性试验研究。发现反冲洗回收水消毒对滤池除锰效果有较大的负面作用,原因是回收水中剩余消毒药剂破坏了滤料层铁锰细菌形成的生物膜,抑制了新的铁锰细菌生长。生产性试验表明,当滤料表面铁锰细菌量达到105个/mL砂数量级后,才能获得较好的除锰效果。在除铁除锰工艺中,不宜对反冲洗回收水进行消毒处理。     

一体化OCO工艺处理生活污水研究

介绍了一种改进型的OCO工艺———一体化膜泥法OCO污水处理工艺。与传统OCO工艺相比 ,具有如下特点 :融生物反应器与二次沉淀池于一体 ,节省项目占地 ,减少基建费用 ;实现了污泥的自动回流 ,减少设备购置、运行和维护费 ;充分利用了生物膜法和活性污泥法的优点。研究结果表明 ,本工艺用于生活污水的处理效果良好。     

Investigation of microbial communities on reverse osmosis membranes used for process water production.

In the present study, the diversity and the phylogenetic affiliation of bacteria in a biofouling layer on reverse osmosis (RO) membranes were determined. Fresh surface water was used as a feed in a membrane-based water purification process. Total DNA was extracted from attached cells from feed spacer, RO membrane and product spacer. Universal primers were used to amplify the bacterial 16S rRNA genes. The biofilm community was analysed by 16S rRNA-gene-targeted denaturing gradient gel electrophoresis (DGGE) and the phylogenetic affiliation was determined by sequence analyses of individual 16S rDNA clones. Using this approach, we found that five distinct bacterial genotypes (Sphingomonas, Beta proteobacterium, Flavobacterium, Nitrosomonas and Sphingobacterium) were dominant genera on surfaces of fouled RO membranes. Moreover, the finding that all five "key players" could be recovered from the cartridge filters of this RO system, which cartridge filters are positioned before the RO membrane, together with literature information where these bacteria are normally encountered, suggests that these microorganisms originate from the feed water rather than from the RO system itself, and represent the fresh water bacteria present in the feed water, despite the fact that the feed water passes an ultrafiltration (UF) membrane (pore size approximately 40 nm), which is able to remove microorganisms to a large extent.     

Contamination potential of drinking water distribution network biofilms.

Drinking water distribution system biofilms were investigated for the presence of hygienically relevant microorganisms. Early biofilm formation was evaluated in biofilm reactors on stainless steel, copper, polyvinyl chloride (PVC) and polyethylene coupons exposed to unchlorinated drinking water. After 12 to 18 months, a plateau phase of biofilm development was reached. Surface colonization on the materials ranged between 4 x 10(6) and 3 x 10(7) cells/cm2, with heterotrophic plate count (HPC) bacteria between 9 x 10(3) and 7 x 10(5) colony-forming units (cfu)/cm2. Established biofilms were investigated in 18 pipe sections (2 to 99 years old) cut out from distribution pipelines. Materials included cast iron, galvanized steel, cement and PVC. Colonization ranged from 4 x 10(5) to 2 x 10(8) cells/cm2, HPC levels varied between 1 and 2 x 10(5) cfu/cm2. No correlation was found between extent of colonization and age of the pipes. Using cultural detection methods, coliform bacteria were rarely found, while Escherichia coli, Pseudomonas aeruginosa and Legionella spp. were not detected in the biofilms. In regular operation, distribution system biofilms do not seem to be common habitats for pathogens. However, nutrient-leaching materials like rubber-coated valves were observed with massive biofilms which harboured coliform bacteria contaminating drinking water.     

Microbiota in Surface Films: an Historical Perspective

Research over the past 50 years has revealed the ubiquitous nature of the organic surface film and the significant enrichment of bacteria in it. This enrichment is greater with certain types of microorganisms and is related to the lipid content of the film. Surface films are trapping devices for bacteria and vehicles for the passive dispersion of bacteria into the atmosphere. The secretions of these bacteria and phytoplankton, as well as proteins and lipids liberated from autolyzing microorganisms, may be important for the formation and regeneration of the surface film.     

MBBR法处理桃浦工业区废水的中试研究

采用MBBR法处理桃浦工业区废水 ,同原有的SBR法相比无论在有机物的去除效果上还是对有机物的耐冲击负荷上都更优越。试验结果表明 ,当HRT为 6～ 15h时 ,MBBR法对COD的平均去除率大于 75%。     

臭氧对生物增强活性炭系统中菌群稳定性影响研究

为提高生物增强活性炭(BEAC)工艺的生物稳定性,进行臭氧工艺对固定的优势菌群稳定性的影响研究。结果表明,臭氧投加量1.5～2.5mg/L,接触时间大于10min时,可有效杀灭进水中的杂菌,且产生的余臭氧量(小于0.25mg/L)不会影响后续工艺中优势菌群的生物活性。通过对比臭氧—BEAC和单独BEAC工艺滤料表面菌群组成随运行时间的变化规律,臭氧—BEAC工艺优势菌在活性炭表面始终占主导地位,菌种组成及生态结构未发生改变,有较好的生物稳定性。单独BEAC工艺运行至6个月时,菌群组成发生较大变化,优势菌数量减少。通过扫描电镜观察,运行6个月的臭氧—BEAC炭上形成菌体重叠的菌团结构,并有较多未被生物覆盖的滤料表面和空缺的地方。单独BEAC工艺活性炭表面粗糙结构较少,被大量污染物与菌团相互包裹的颗粒所覆盖。     

接触氧化工艺中生物填料的发展及应用

选择合适的生物填料可以有效地提高接触氧化工艺的处理效果。对接触氧化工艺中采用较多的硬性、软性、半软性、组合型、悬浮型及固定化微生物型填料进行了分类介绍,分析了各自的构造、挂膜性能、有机物去除效率等。认为悬浮型、生物密集型、固定化微生物型填料将会成为今后生物填料的发展方向。     

The role of aquatic ecosystems as reservoirs of antibiotic resistant bacteria and antibiotic resistance genes.

The widespread and indiscriminate use of antibiotics has led to the development of antibiotic resistance in pathogenic, as well as commensal, microorganisms. Resistance genes may be horizontally or vertically transferred between bacterial communities in the environment. The recipient bacterial communities may then act as a reservoir of these resistance genes. In this study, we report the incidence of antibiotic resistance in enteric bacteria isolated from the Mhlathuze River and the distribution of genetic elements that may be responsible for the observed antibiotic resistance. The resistance of the enteric bacteria isolated over a period of one year showed that resistance to the older classes of antibiotics was high (94.7% resistance to one antibiotic and 80.8% resistance to two antibiotics). Furthermore, antibiotic resistance data of the environmental isolates showed a strong correlation (r = 0.97) with data obtained from diarrhoea patients. PCR based methods demonstrated that class 1 integrons were present in >50% of the environmental bacterial isolates that were resistant to multiple antibiotics. This class of integrons is capable of transferring genes responsible for resistance to beta-lactam, aminoglycoside, sulfonamide and quaternary ammonium antimicrobial agents. Conjugate plasmids were also isolated, but from a small percentage of isolates. This study showed that the Mhlathuze River (a) is a medium for the spread of bacterial antibiotic resistance genes, (b) acts as a reservoir for these genes and (c) due to socio-economic pressures, may play a role in the development and evolution of these genes along this river system.