基于好氧反硝化及反硝化聚磷菌强化的低温低碳氮比生活污水生物处理中试研究

【背景】低碳氮比生活污水很难达标处理,多级A/O工艺、生物强化技术及生物膜技术的有机结合可有效解决这一问题。【目的】开发出一种泥膜共生多级A/O工艺并进行中试研究,驯化出高效脱氮除磷菌剂并对系统进行生物强化。【方法】通过测定中试设备出水及污水处理厂出水化学需氧量(Chemical oxygen demand,COD)、氨氮(NH_4~+-N)、硝氮(NO_3~--N)、总氮(Total nitrogen,TN)、总磷(Total phosphorus,TP)对比分析两种工艺的污染物去除效能,利用高通量测序技术对比生物强化技术对系统微生物群落结构的影响。【结果】中试设备对COD、NH_4~+-N、NO_3~--N、TN、TP的去除效果均优于污水处理厂的处理工艺;驯化的低温好氧反硝化菌TN去除率最大值可达84.21%,驯化的低温反硝化聚磷菌群对磷的去除率最高可达85.75%;利用驯化菌群对中试设备进行生物强化后较好地改善了系统NH_4~+-N、NO_3~--N、TN、TP的去除效果;经生物强化后,具有好氧反硝化和反硝化聚磷功能的Pseudomonas菌群明显增多。【结论】泥膜共生多级A/O工艺对于低碳氮比生活污水的处理具有很好的效果,利用生物强化技术可有效提高低温条件下系统污染物去除效能。     

Biological detoxification of precious metal processing wastewaters

A biological treatment plant is utilized at the Homestake Mine in Lead, SD, to effect detoxification of a daily discharge of 4 million gallons of wastewater. The wastewater matrix requiring treatment contains cyanide, ammonia, toxic heavy metals, and a variable component of toxic chemicals associated with extractive metallurgy and mining operations. Rotating biological contactors (RBCs) are used to attach the biofilm. Cyanides and heavy metals concentrations are reduced by 95–98%. The treated discharge makes up as much as 60% of the total flow in a cold‐water trout fishery. This receiving stream, which remained lifeless for over 100 years as a mine drainage, has now become an established trout fishery and recently yielded a state record trout.     

A study of the effect of isothiazolones on the performance and characteristics of a laboratory-scale rotating biological contactor

AIMS: To study the effect of the isothiazolone biocide (Kathon WT) on the performance of laboratory-scale rotating biological contactors (RBCs) and their component biofilms. METHODS AND RESULTS: Biofilms were established on the RBCs and then exposed to 0.7-15 p.p.m. isothiazolones. Young, 1-week-old, biofilms were found to attain treatment efficiency equal to that of mature, 2-month-old, biofilms. Isothiazolone concentrations at 3 p.p.m. and above caused a progressive decline in treatment efficiency and 15 p.p.m. isothiazolones inhibited all microbial activity and resulted in the death of the biofilms. Bio-oxidation and the biodegradation of isothiazolones within the biofilms ontinued unhindered at concentrations which caused the total inhibition of planktonic bacteria. CONCLUSION: There was at least a 10-fold difference in susceptibility of planktonic and biofilm bacteria to isothiazolones. The chemical oxygen demand (COD) test was shown to be a reliable tool for investigating the efficiency of wastewater treatment units when the influent contains isothiazolones, while the biochemical oxygen demand (BOD) was unreliable due to the inhibition of bio-oxidation by the biocide. SIGNIFICANCE AND IMPACT OF THE STUDY: The results show that RBCs can be used to treat effluents containing isothiazolones at concentrations up to 1.5 p.p.m.     

Biofilm reactors in anaerobic wastewater treatment

Attached biofilm reactors provide the means for implementing energy-efficient anaerobic wastewater treatment at full scale. Progress has been made in the development of fixed, expanded and fluidized bed anaerobic processes by addressing fundamental reactor design issues. Several new biofilm reactor concepts have evolved from recent studies.     

一株吡啶降解菌Pseudomonas sp.ZX08的生物膜形成特性及影响因素

【背景】煤化工企业排放的废水中含有大量难降解、高毒性的有机污染物,采用以高效降解菌为基础的生物强化技术对其进行处理,是一种经济可行的策略;而促进高效降解菌在载体材料表面的生物膜形成,有助于提升生物膜法废水处理系统的效能。【目的】探究一株吡啶高效降解菌Pseudomonas sp. ZX08的生物膜形成过程和特性,识别不同的环境因子如温度、pH、Na⁺、K⁺、Ca²⁺、Mg²⁺等对其生物膜形成的影响规律,为实现人工调控其在实际废水处理系统中的成膜过程提供理论依据。【方法】采用改良的微孔板生物膜培养与定量方法,以单因子影响实验测定不同条件下菌株在12孔板内的生物膜形成量和浮游态细菌量;采用激光共聚焦显微镜(confocallaserscanning microscope,CLSM)观察和分析生物膜的结构特征。【结果】Pseudomonas sp. ZX08菌株具有良好的吡啶降解性能,且生物膜形成能力较强,CLSM观察到其在载体表面形成的生物膜可达40-50mm;生物膜外层的活细胞比例更高,分泌的胞外蛋白...     

基于Lux型群体感应系统干预的生物被膜调控在污水处理中的研究进展与前景

基于Lux型群体感应系统的生物被膜调控在污水处理中的研究备受关注,群体感应系统的干预包括正向强化和负向削弱两类。群体感应系统的正向强化作用可提高生物膜法污水处理中的挂膜速度,提高污水处理效率,促进活性污泥中胞外聚合物(Extracellular polymeric substance,EPS)和可溶性微生物产物(Soluble microbial products,SMP)的生成,提高生物被膜的产量;群体感应的负向削弱作用可以降解生物被膜形成过程中所需要的信号分子,切断生物被膜形成的基因表达过程,有效抑制MBR膜表面生物被膜的形成,防止膜污染。对信号分子酰基高丝氨酸内酯(N-acyl homoserine lactone,AHLs)的结构和作用机理的进一步研究、群体感应淬灭菌的固定化技术与应用、多种防治膜污染方法的协同效果验证及群体感应干预在更多污水处理领域的应用可行性是该领域要研究的几个重要方向。     

Biofilm formation and interactions of bacterial strains found in wastewater treatment systems

Biofilm formation and adherence properties of 13 bacterial strains commonly found in wastewater treatment systems were studied in pure and mixed cultures using a crystal violet microtiter plate assay. Four different culture media were used, wastewater, acetate medium, glucose medium and diluted nutrient broth. The medium composition strongly affected biofilm formation. All strains were able to form pure culture biofilms within 24 h in at least one of the tested culture media and three strains were able to form biofilm in all four culture media, namely Acinetobacter calcoaceticus ATCC 23055, Comamonas denitrificans 123 and Pseudomonas aeruginosa MBL 0199. The adherence properties assessed were initial adherence, cell surface hydrophobicity, and production of amyloid fibers and extracellular polymeric substances. The growth of dual-strain biofilms showed that five organisms formed biofilm with all 13 strains while seven formed no or only weak biofilm when cocultured. In dual-strain cultures, strains with different properties were able to complement each other, giving synergistic effects. Strongest biofilm formation was observed when a mixture of all 13 bacteria were grown together. These results on attachment and biofilm formation can serve as a tool for the design of tailored systems for the degradation of municipal and industrial wastewater.     

Mathematical Model and Mechanisms for Biofilm Wastewater Treatment Systems

Summary Fundamental theoretical depiction is still lacking on biofilm wastewater treatment systems up to today. A mathematical model of biofilm wastewater treatment systems, taking account of suspended microorganisms and some factors influencing biofilm formation and stabilization, is developed in this paper. By theoretical and numerical analyses, the factors influencing biofilm formation and stabilization, such as the dilution rate, influent organic concentration, detachment and initial inoculum concentration etc, are discussed. Qualitative investigations were carried out and suggestions on industrial applications are then proposed. This paper not only plays an important role in understanding the physical mechanisms of biofilm dynamics, but also has far-reaching implications for industrial practices.     

生物膜型污水脱氮系统中膜结构及微生物生态研究进展

生物膜法污水脱氮系统主要利用生物膜中脱氮功能微生物的代谢活动去除氮素,从而达到净化水质的目的,研究脱氮生物膜的微观结构和微生物生态是揭示生物膜脱氮机理从而提高脱氮效率的重要途径.本文综述了生物膜型污水脱氮系统类型、生物膜微观结构特征及其影响因素、生物膜型污水脱氮系统内氮素传质过程、脱氮机理和生物膜数学模型等方面的研究进展.另外,本文介绍了生物膜型污水脱氮系统内生物膜脱氮功能微生物分布特征,不同生物膜脱氮系统、底物、运行条件和时间对功能微生物群落影响,及新型脱氮功能微生物等方面的研究进展,为生物膜脱氮技术的深入研究提供参考.     

Wastewater treatment with particulate biofilm reactors

The review presented in this paper focuses on applications of particulate biofilm reactors (e.g. Upflow Sludge Blanket, Biofilm Fluidized Bed, Expanded Granular Sludge Blanket, Biofilm Airlift Suspension, Internal Circulation reactors). Several full-scale applications for municipal and industrial wastewater treatment are presented and illustrated, and their most important design and operation aspects (e.g. biofilm formation, hydrodynamics, mass transfer, mixing) are analysed and discussed. It is clear from the review that this technology can be considered a grown up technology for which good design and scale-up guidelines are available.     

Phosphorus removal coupled to bioenergy production by three cyanobacterial isolates in a biofilm dynamic growth system

In the present study a closed incubator, designed for biofilm growth on artificial substrata, was used to grow three isolates of biofilm-forming heterocytous cyanobacteria using an artificial wastewater secondary effluent as the culture medium. We evaluated biofilm efficiency in removing phosphorus, by simulating biofilm-based tertiary wastewater treatment and coupled this process with biodiesel production from the developed biomass. The three strains were able to grow in the synthetic medium and remove phosphorus in percentages, between 6 and 43%, which varied between strains and also among each strain according to the biofilm growth phase. Calothrix sp. biofilm turned out to be a good candidate for tertiary treatment, showing phosphorus reducing capacity (during the exponential biofilm growth) at the regulatory level for the treated effluent water being discharged into natural water systems.

Besides phosphorus removal, the three cyanobacterial biofilms produced high quality lipids, whose profile showed promising chemical stability and combustion behavior. Further integration of the proposed processes could include the integration of oil extracted from these cyanobacterial biofilms with microalgal oil known for high monounsaturated fatty acids content, in order to enhance biodiesel cold flow characteristics.     

Biodegradation of aniline using light carriers with optimised surface in TPIFB

The successful microbial immobilisation along with fluidisation are keys to highly effective microbiological wastewater treatment. The Inverse Three-Phase Fluidised Bed (TPIFB) is a novel technique proposed for wastewater treatment. In the present work a method based on analysis of the factors governing the biofilm formation has been developed for production of biocarriers for packing in a TPIFB for biodegradation of aniline containing wastewater. Tests of the treated samples show that the procedure ensures forming of a steady biofilm. The continuous cultivation of Pseudomonas putuda and Ps. aeruginosa in TPIFB with aniline as a single substrate provides high biodegradation rates and stability of the process of wastewater treatment within one-year-long operation. Electrochemical probe for monitoring and control the biofilm growth proves its reliability and efficiency in TPIFB.     

Detachment forces and their influence on the structure and metabolic behaviour of biofilms

The biofilm reactor has been frequently applied in wastewater treatment. The formation, structure and metabolic activity of the biofilms are closely associated with the detachment forces in the reactors. This paper reviews the essential role of detachment forces in the biofilm process. A more compact, stable and denser biofilm can be formed at a relatively higher detachment force. The detachment force has significant influence on the structure, mass transfer, production of exopolysaccharides, metabolic and genetic properties of the biofilm. In an engineering sense, the detachment forces can be manipulated, as a control parameter, to produce a more stable and compact biofilm for use in wastewater treatment. The molecular and genetic mechanisms responsible for the detachment force-associated phenomena are not yet fully understood.     

Resistance of bioparticles formed of phosphate-accumulating bacteria and zeolite to harsh environmental conditions

Extreme environmental conditions, such as pH fluctuations, high concentrations of toxicants or grazing of protozoa, can potentially be found in wastewater treatment systems. This study was carried out to provide specific evidence on how ‘bioparticles’ can resist these conditions. The term ‘bioparticle’ is used to describe a particle comprising natural zeolitized tuff with a developed biofilm of the phosphate-accumulating bacterial species, Acinetobacter junii, on the surface. The bacteria in the biofilm were protected from the negative influence of extremely low pH, high concentrations of benzalkonium-chloride and grazing by Paramecium caudatum and Euplotes affinis, even under conditions that caused complete eradication of planktonic bacteria. During an incubation of 24?h, the biofilms were maintained and bacteria detached from the bioparticles, thus bioaugmenting the wastewater. The bioparticles provided a safe environment for the survival of bacteria in harsh environmental conditions and could be used for successful bioaugmentation in wastewater treatment plants.     

Experimental and theoretical investigations of rotating algae biofilm reactors (RABRs): Areal productivity,nutrient recovery,and energy efficiency

Microalgae biofilms have been demonstrated to recover nutrients from wastewater and serve as biomass feedstock for bioproducts. However, there is a need to develop a platform to quantitatively describe microalgae biofilm production, which can provide guidance and insights for improving biomass areal productivity and nutrient uptake efficiency. This paper proposes a unified experimental and theoretical framework to investigate algae biofilm growth on a rotating algae biofilm reactor (RABR). Experimental laboratory setups are used to conduct controlled experiments on testing environmental and operational factors for RABRs. We propose a differential–integral equation-based mathematical model for microalgae biofilm cultivation guided by laboratory experimental findings. The predictive mathematical model development is coordinated with laboratory experiments of biofilm areal productivity associated with ammonia and inorganic phosphorus uptake by RABRs. The unified experimental and theoretical tool is used to investigate the effects of RABR rotating velocity, duty cycle (DC), and light intensity on algae biofilm growth, areal productivity, nutrient uptake efficiency, and energy efficiency in wastewater treatment. Our framework indicates that maintaining a reasonable light intensity range improves biomass areal productivity and nutrient uptake efficiency. Our framework also indicates that faster RABR rotation benefits biomass areal productivity. However, maximizing the nutrient uptake efficiency requires a reasonably low RABR rotating speed. Energy efficiency is strongly correlated with RABR rotating speed and DC.     

Moving-Medium Biofilm Reactors

Four moving-medium biofilm reactors treating wastewater were reviewed in this paper: the rotating biological contactor (RBC), the moving bed biofilm reactor (MBBR), the vertically moving biofilm reactor (VMBR) and the fluidized-bed reactor (FBR). The RBC process has been applied widely. MBBR is a good process for upgrading current wastewater treatment systems. VMBR is suitable for treating small wastewater flows. FBR can maximize pollutant removals and minimize sludge production.     

The effect of harvesting on biomass production and nutrient removal in phototrophic biofilm reactors for effluent polishing

An increasing number of wastewater treatment plants require post-treatment to remove residual nitrogen and phosphorus. This study investigated various harvesting regimes that would achieve consistent low effluent concentrations of nitrogen and phosphorus in a phototrophic biofilm reactor. Experiments were performed in a vertical biofilm reactor under continuous artificial lighting and employing artificial wastewater. Under similar conditions, experiments were performed in near-horizontal flow lanes with biofilms of variable thickness. It was possible to maintain low nitrogen and phosphorus concentrations in the effluent of the vertical biofilm reactor by regularly harvesting half of the biofilm. The average areal biomass production rate achieved a 7 g dry weight m^?2 day^?1 for all different harvesting frequencies tested (every 2, 4, or 7 days), corresponding to the different biofilm thicknesses. Apparently, the biomass productivity is similar for a wide range of biofilm thicknesses. The biofilm could not be maintained for more than 2 weeks as, after this period, it spontaneously detached from the carrier material. Contrary to the expectations, the biomass production doubled when the biofilm thickness was increased from 130 μm to 2 mm. This increased production was explained by the lower density and looser structure of the 2 mm biofilm. It was concluded that, concerning biomass production and labor requirement, the optimum harvesting frequency is once per week.     

Capsular polysaccharides of cultured phototrophic biofilms

Phototrophic biofilm samples from an Italian wastewater treatment plant were studied in microcosm experiments under varying irradiances, temperatures and flow regimes to assess the effects of environmental variables and phototrophic biomass on capsular exopolysaccharides (CPS). The results, obtained from circular dichroism spectroscopy and High Performance Liquid Chromatography, suggest that CPS have a stable spatial conformation and a complex monosaccharide composition. The total amount present was positively correlated with the biomass of cyanobacteria and diatoms, and negatively with the biovolume of green algae. The proportion of uronic acids showed the same correlation with these taxon groups, indicating a potential role of cyanobacteria and diatoms in the removal of residual nutrients and noxious cations in wastewater treatment. While overall biofilm growth was limited by low irradiance, high temperature (30°C) and low flow velocity (25 l h^?1) yielded the highest phototrophic biomass, the largest amount of CPS produced, and the highest proportion of carboxylic acids present.     

From microbial fuel cell (MFC) to microbial electrochemical snorkel (MES): maximizing chemical oxygen demand (COD) removal from wastewater

The paper introduces the concept of the microbial electrochemical snorkel (MES), a simplified design of a “short-circuited” microbial fuel cell (MFC). The MES cannot provide current but it is optimized for wastewater treatment. An electrochemically active biofilm (EAB) was grown on graphite felt under constant polarization in an urban wastewater. Controlling the electrode potential and inoculating the bioreactor with a suspension of an established EAB improved the performance and the reproducibility of the anodes. Anodes, colonized by an EAB were tested for the chemical oxygen demand (COD) removal from urban wastewater using a variety of bio-electrochemical processes (microbial electrolysis, MFC, MES). The MES technology, as well as a short-circuited MFC, led to a COD removal 57% higher than a 1000 Ω-connected MFC, confirming the potential for wastewater treatment.     

From microbial fuel cell (MFC) to microbial electrochemical snorkel (MES): maximizing chemical oxygen demand (COD) removal from wastewater

The paper introduces the concept of the microbial electrochemical snorkel (MES), a simplified design of a "short-circuited" microbial fuel cell (MFC). The MES cannot provide current but it is optimized for wastewater treatment. An electrochemically active biofilm (EAB) was grown on graphite felt under constant polarization in an urban wastewater. Controlling the electrode potential and inoculating the bioreactor with a suspension of an established EAB improved the performance and the reproducibility of the anodes. Anodes, colonized by an EAB were tested for the chemical oxygen demand (COD) removal from urban wastewater using a variety of bio-electrochemical processes (microbial electrolysis, MFC, MES). The MES technology, as well as a short-circuited MFC, led to a COD removal 57% higher than a 1000 Ω-connected MFC, confirming the potential for wastewater treatment.