Partial nitrification of sludge reject water using suspended and granular biomass

BACKGROUND: Partial nitrification–Anammox is a combined promising advanced biological process for the removal of nitrogen from wastewater, which allows important savings in energy consumption, sludge production, and organic carbon. Granular biomass appears to be an interesting alternative to conventional activated sludge, mainly because of its better settling properties. This study deals with the experimental results of a comparison between a conventional and a granular sequencing batch reactor (SBR) for the partial nitrification of reject water. RESULTS: After some days of operation, 30 days in the conventional SBR (system A) and 100 days in the granular SBR (system B), partial nitrification was achieved. Granular sludge showed much better settling properties than suspended biomass, with values of sludge volumetric index (SVI₁₀) of 130 mL g^?1 in system A and 38 mL g^?1 in system B. Consequently, the solids concentration within the granular reactor was three times higher than for the conventional system while the concentration of solids in the effluent was 10 times higher in the conventional SBR. Morphology, microstructure and microbial populations in both systems were also studied. CONCLUSION: A partial nitrification process was successfully achieved in both systems, obtaining an effluent with a NO₂^?‐N/NH₄⁺‐N ratio near 1, suitable for a following Anammox process. Granular biomass, mostly formed by round particles, showed better settling properties, leading to better sludge–effluent separation as well as higher biomass retention in the reactor. The granulation process does not affect bacterial populations, since they were the same in both systems. Copyright © 2011 Society of Chemical Industry     

Storage of biodegradable polymers by an enriched microbial community in a sequencing batch reactor operated at high organic load rate

The production of polyhydroxyalkanoates (PHAs) from organic acids by mixed bacterial cultures using a process based on aerobic enrichment of activated sludge, that selects for mixed microbial cultures able to store PHAs at high rates and yields, is described. Enrichment resulted from the selective pressure established by periodic feeding the carbon source in a sequencing batch reactor (SBR); a mixture of acetic, lactic and propionic acids was fed at high frequency (2 hourly), high dilution rate (1 d⁻¹), and at high organic load rate (12.75 g chemical oxygen demand (COD) L⁻¹ d⁻¹). The performance of the SBR was assessed by microbial biomass and PHA production as well as the composition and polymer content of the biomass. A final batch stage was used to increase the polymer concentration of the excess sludge produced in the SBR and in which the behaviour of the biomass was investigated by determining PHA production rates and yields. The microbial biomass selected in the SBR produced PHAs at high rate [278 mg PHAs (as COD) g biomass (as COD)⁻¹ h⁻¹, with a yield of 0.39 mg PHAs (as COD) mg removed substrates (as COD)⁻¹], reaching a polymer content higher than 50% (on a COD basis). The stored polymer was the copolymer poly(3‐hydroxybutyrate/3‐hydroxyvalerate) [P(HB/HV)], with an HV fraction of 18% mol mol⁻¹. The microbial community selected in the SBR was analysed by DGGE (denaturing gradient gel electrophoresis). The operating conditions of the SBR were shown to select for a restricted microbial population which appeared quite different in terms of composition with respect to the initial microbial cenosis in the activated sludge used as inoculum. On the basis of the sequencing of the major bands in the DGGE profiles, four main genera were identified: a Methylobacteriaceae bacterium, Flavobacterium sp, Candidatus Meganema perideroedes, and Thauera sp. The effects of nitrogen depletion (ie absence of growth) and pH variation were also investigated in the batch stage and compared with the SBR operative mode. Absence of growth did not stimulate higher PHA production, so indicating that the periodic feed regime fully exploited the storage potential of the enriched culture. Polymer production rates remained high between pH 6.5 and 9.5, whereas the HV content in the stored polymer strongly increased as the pH value increased. This study shows that polymer composition in the final batch stage can readily be controlled independently from the feed composition in the SBR. Copyright © 2005 Society of Chemical Industry     

The effect of COD/N ratio on process performance and membrane fouling in a submerged bioreactor

Influent chemical oxygen demand/nitrogen (COD/N) ratio is used to control fouling in membrane bioreactor (MBR) systems. However, COD/N also affects the physicochemical and biological properties of MBR biomass. The current study examined the relationship between COD/N ratio in feed wastewater and extracellular polymeric substances (EPS) production in MBRs. Two identical submerged MBRs with different COD/N ratios of 10:1 and 5:1 were operated in parallel. The cation concentration and floc-size of the sludge were measured. The composition and characteristics of bound EPS and soluble microbial products (SMP) under each COD/N ratio were also examined. Batch tests were conducted in 1000 mL bottles to study the process of the release of foulants from the sludge when 1 g of (NH₄⁺-N)/L was added. Results showed that the influent COD/N ratio could change the physicochemical properties of EPS and SMP. Moreover, excessive NH₄⁺ in the supernatant could facilitate the role of NH₄⁺ as a monovalent cation, the replacement of the polyvalent cation in bound EPS, and even the extraction of EPS components from the surface of the sludge to form new SMP.     

无排泥条件下膜生物反应器污泥混合液可滤性分析

膜生物反应器（MBR）在无排泥条件下运行100 d,定期对溶解性微生物产物（SMP）、SMP分子量分布、胞外聚合物（EPS）中的蛋白质和多糖进行监测,应用修正的污染指数（MFI）考察污泥混合液可滤性的变化。实验表明：长时间无排泥运行模式下将导致污泥混合液可滤性的恶化;污泥混合液上清液中分子量（M_w）大于10 kDa 的SMP浓度对污泥混合液的可滤性产生强烈的负面影响;污泥浓度（MLSS）与混合液可滤性之间关系复杂,MLSS对污泥可滤性的影响存在一个临界值;EPS中的蛋白质60 d后发现可被微生物迅速降解,多糖类物质对污泥混合液可滤性有较强的负面影响。     

Start up of biological sequencing batch reactor (SBR) and short‐term biomass acclimation for polyhydroxyalkanoates production

BACKGROUND: The adaptation/selection of mixed microbial cultures under feast/famine conditions is an essential step for polyhydroxyalkanoates (PHA) production. This study investigated the short‐term adaptation of a mixed microbial culture (activated sludge) during the start up of a sequencing batch reactor (SBR). RESULTS: Four different SBR runs were performed starting from different inocula and operated at the same organic load rate (8.5 gCOD L^?1 d^?1) and hydraulic retention time (1 day). At 3–7 days from SBR start up, the selected biomass was able to store PHA at comparable rate and yield with those obtained after long‐term acclimation. Independently from the time passed, a short feast phase was the key parameter to obtain PHA storage at high rate and yield in the following accumulation stage (244 mgCOD g^?1CODnonPolym h^?1 for specific storage rate and 48% COD COD^?1 as PHA content in the biomass). The DGGE profiles showed that the good storage performance and the structure of the microbial community were not fully correlated. CONCLUSIONS: The results suggest a new strategy for operating the PHA accumulation stage directly in the SBR, after very short biomass adaptation, instead of using two separate reactors for biomass enrichment and PHA accumulation, respectively. © 2012 Society of Chemical Industry     

SBR恒曝气量好氧硝化过程动态DO模拟:模型辨识与KLa确定

通过简化活性污泥法1号模型(activated sludge model No.1,ASM1)建立两步硝化反应的数学模型,实现了对序批式反应器(sequencing batch reactor,SBR)恒曝气量好氧过程中溶解氧(dissolved oxygen,DO)动态变化过程的数学模拟,模型辨识科学地区分了可以直接取值的参数包括产率系数、DO饱和常数(或底物饱和常数)和需要重新估计的参数。采用文献推荐参数值模拟了过程中主要状态变量的动力学过程,模拟结果呈现出了多个DO平台,这与实际反应结果数据相符,验证了所建模型的正确性。优化实验设计,获取了典型SBR恒曝气好氧硝化过程动态DO数据,通过理论分析和对数据进行二阶微分处理提出了确定总氧传递系数K_La和相对饱和溶解氧S_O^eq的简单方法,为后续参数估计奠定了基础。     

微生物代谢产物对膜生物反应器膜污染的影响

针对膜生物反应器（MBR）在运行过程中溶解性微生物代谢产物（SMP）及胞外聚合物（EPS）对膜污染进行研究。实验过程中对MBR内的污泥混合液进行了定期膜阻力监测。结果表明,SMP和EPS对膜过滤阻力有负面的影响。SMP中相对分子质量分布（Mw）在3～10 kDa对膜内部阻力影响显著,SMP中Mw＞10 kDa的大分子有机物及EPS浓度对膜外部阻力影响明显。通过傅里叶转换红外光谱（FTIR）检测膜表面污染物表明,EPS主要由多聚糖、蛋白质和腐殖酸组成,而污染层中的SMP主要是多聚糖和腐殖酸。     

低有机负荷下不同载体对好氧污泥颗粒化的影响

针对活性污泥在低有机负荷下难以实现颗粒化的现状,通过在不同序批式活性污泥（sequencing batch reactor activated sludge process,SBR）反应器中微生物生长的对数期分别投加聚合硫酸铁、硫酸铝和硅藻土来强化好氧颗粒污泥的形成,并对比分析了不同载体的强化造粒机制。结果表明：投加聚合硫酸铁、硅藻土和硫酸铝后,污泥特性得到明显提高,污泥颗粒化所需时间分别提前了11d、7d和4d,而且与对照组的提前解体相比,载体强化后所形成颗粒污泥的结构更为密实,均具有良好的稳定性。而不同于聚合硫酸铁和硅藻土,投加硫酸铝后,污泥胞外聚合物（extracellular polymeric substances,EPS）含量明显增加,由之前的171.31mg/gMLVSS升高至223.47mg/gMLVSS,蛋白（PN）可达205.69mg/gMLVSS,且蛋白（PN）/多糖（PS）可达10以上,这就说明通过刺激污泥EPS的分泌来促进微生物聚集也是硫酸铝强化颗粒污泥形成的作用方式之一。另外,三维荧光光谱分析结果显示,载体的投加能够对污泥EPS的结构产生影响,这也可能在一定程度上促进了污泥的颗粒化进程。     

Temperature dependency of granule characteristics and kinetic behavior in UASB reactors

When an inhibitory substrate, phenol, was treated under mesophilic conditions (25, 30, 35, and 40 °C), the upflow anaerobic sludge bed (UASB) reactors at 30 °C resulted in the greatest amount of biomass and the largest granule size, while the UASB reactors at 25 °C resulted in the smallest granule size and the greatest amount of wash‐out of sludge. The granule size tended to be negatively correlated with the amount of wash‐out of sludge. With an increase in temperature, the kinetic constant k for anaerobic phenol degradation increased and the half saturation constant (K_s) decreased. The mass fraction of methanogens (f) increased with increasing operational temperature in the UASB reactors and the activation energy (E_a) for acetate methanogenesis was larger than that for phenol acidogenesis in the batch reactors, indicating that the operational temperature imposes a more influential effect on methanogens than on acidogens. From the results of the activity of acidogens and methanogens (expressed in specific COD utilization rate), the rate‐limiting step is phenol acidogenesis. Copyright © 2004 Society of Chemical Industry     

强化好氧颗粒污泥稳定性的研究进展

系统回顾了有关好氧颗粒污泥稳定性方面的研究进展,简要介绍了好氧颗粒污泥的形成机理,主要包括“丝状菌假说”、“胞外聚合物假说”、“选择压驱动假说”、“自凝聚假说”;着重分析了影响好氧颗粒污泥稳定性的主要因素有温度、pH值、有机负荷率与氨氮浓度、溶解氧与颗粒粒径、饱食-饥饿期、水力剪切力、污泥龄和有毒有害物质等;详细论述了抑制丝状膨胀、促进胞外聚合物的分泌、富集慢速增长的微生物和强化颗粒内核等措施可以强化好氧颗粒污泥的稳定性,并提出了对好氧颗粒污泥的形成机理以及功能菌群进行更深入的研究将会是今后的研究重点,进而为好氧颗粒污泥的工业化应用作铺垫。     

微生物颗粒在废水处理中的应用与研究

微生物颗粒是微生物在适当的环境条件下,相互聚集形成的自聚集体。由于微生物颗粒具有良好的生物活性、沉降速度快、无需载体、易于固液分离等许多优点,在废水处理中得到了广泛的研究与应用。微生物颗粒化是一个复杂的过程,受多种因素影响。作者对近些年来国内外的一些研究成果,从厌氧颗粒污泥、好氧颗粒污泥、菌丝球3个方面综述了微生物颗粒在废水处理中的研究进展,内容包括颗粒的基本特性、微生物相,主要影响因素及其颗粒化过程。     

协同调控C/N负荷提升好氧颗粒污泥亚硝化性能

以异养颗粒污泥为接种污泥启动SBR反应器,通过协同调控进水碳、氮负荷比值,成功获得了具备短程亚硝化功能的自养型颗粒污泥。基于对粒径分布、胞外聚合物（EPS）和功能菌动力学活性的分析,系统阐述了影响污泥性状与功能演化的关键因素。结果表明,随着氨氧化菌（AOB）活性（μ_NO3-N）的持续增强和对亚硝酸盐氧化菌（NOB）活性（μ_NO3-N）的有效抑制,反应器对亚硝态氮（NO₂^--N）的累积速率可达1.34 kg·（m³·d）^-1。污泥平均粒径由1.4 mm增至2.2 mm,颜色变为红棕色,沉降性能明显改善。得益于EPS的不断累积,颗粒污泥在高选择压条件下（沉淀时间3 min）,仍能有效截留、固定AOB。曝气反应期间,游离氨（FA）和游离亚硝酸（FNA）对NOB的选择性抑制也是实现稳定亚硝化反应的重要原因。     

颗粒污泥处理高负荷有机含油废水的形成过程及特性探究

在序批式反应器(SBR)内接种絮状物质,以实际高负荷含油废水为探究对象,在中温条件下考察了进水有机负荷(OLR)对颗粒污泥形成的影响,分析了OLR对颗粒污泥粒径、生物量、微生物活性、胞外聚合物(EPS)组成的演化规律,探究了OLR影响颗粒污泥对化学需氧量(COD)与溶解性油类的去除特性.结果表明,当进水OLR由0.5 ...     

Start up of a pilot scale aerobic granular reactor for organic matter and nitrogen removal

Aerobic granulation is a promising technology for the removal of nutrients in wastewater. Since research to date is mainly focused at laboratory scale, a pilot‐scale sequencing batch reactor (100 L) was operated to obtain granular sludge in aerobic conditions grown on acetate as organic carbon substrate. Selective pressure created by means of decreasing settling time and increasing organic loading rate (OLR) enhanced the formation of aerobic granular sludge. Granules appeared after 6 days and reached an average diameter around 3.5 mm. The settling velocity value should be higher than 11 m h^?1 in order to remove flocculent biomass. The reactor treated OLRs varying between 2.5 and 6.0 g COD L^?1 d^?1 reaching removal efficiencies around 96%, which demonstrates the high activity and the ability of the system to withstand high OLR. Nevertheless, a rapid increase in the OLR produced a loss of biomass in the reactor due to breakage of the granules. Copyright © 2011 Society of Chemical Industry     

Exploiting olive oil mill effluents as a renewable resource for production of biodegradable polymers through a combined anaerobic–aerobic process

BACKGROUND: The performance of a three‐stage process for polyhydroxyalkanoate (PHA) bioproduction from olive oil mill effluents (OME) has been investigated. In the first anaerobic stage OME were fermented in a packed bed biofilm reactor into volatile fatty acids (VFAs). This VFA‐rich effluent was fed to the second stage, operated in an aerobic sequencing batch reactor (SBR), to enrich mixed cultures able to store PHAs. Finally, the storage response of the selected consortia was exploited in the third aerobic stage, operated in batch conditions. RESULTS: The anaerobic stage increased the VFA percentage in the OME from 18% to ～32% of the overall chemical oxygen demand (COD). A biomass with high storage response was successfully enriched in the SBR fed with the fermented OME at an organic load rate of 8.5 gCOD L^?1 d^?1, with maximum storage rate and yield (146 mgCOD gCOD^?1 h^?1 and 0.36 COD COD^?1, respectively) very similar to those obtained with a synthetic VFA mixture. By means of denaturing gradient gel electrophoresis (DGGE) analysis, different bacterial strains were identified during the two SBR runs: Lampropedia hyalina and Candidatus Meganema perideroedes, with the synthetic feed or the fermented OMEs, respectively. In the third stage, operated at increasing loads, the maximum concentration of the PHA produced increased linearly with the substrate fed. Moreover, about half of the stored PHAs were produced from substrates other than VFAs, mostly alcohols. CONCLUSION: The results obtained indicate that the process is effective for simultaneous treatment of OME and their valorization as a renewable resource for PHA production. Copyright © 2009 Society of Chemical Industry     

Mn(Ⅱ)对好氧颗粒污泥微生物活性的影响

针对城市污水中重金属离子短期超标影响污水生物处理系统正常运行的问题,采用好氧颗粒污泥SBR反应器,研究了不同浓度Mn(Ⅱ)短期冲击下对好氧颗粒污泥污染物去除性能、外观结构和微生物活性的影响。试验结果表明,好氧颗粒污泥受不同浓度Mn(Ⅱ)10 d的冲击后,COD去除率受Mn(Ⅱ)影响较小,Mn(Ⅱ)会轻微促进AGS对TN的去除。Mn(Ⅱ)分别为0.5、1.0、3.0 mg/L可提高好氧颗粒污泥的活性,在相应浓度的冲击下SOUR分别提高16.0%、108.5%、51.8%,TTC-ETS分别提高了7.7%、112.4%、45.7%。5.0 mg/L Mn(Ⅱ)对SOUR和TTC-ETS的抑制率分别为13.8%和33.5%。     

好氧饥饿对膨胀污泥硝化性能及污泥特性的影响

采用SBR好/缺氧工艺,考察了好氧饥饿对于丝状菌膨胀污泥中硝化细菌活性及污泥性能的影响。结果表明,14 d的好氧饥饿过程(无外加底物,保持曝气)中,氨氧化细菌(ammonia-oxidizing bacteria, AOB)表现出更高的饥饿敏感性,其好氧衰减速率[(0.42±0.06)d^-1)高于亚硝酸盐氧化菌(nitrite-oxidizing bacteria, NOB)的好氧衰减速率[(0.34±0.05)d^-1]。恢复阶段初期,系统出现了明显的亚硝酸盐积累现象,这主要归因于AOB具有在环境发生改变时做出快速反应的能力,具体体现在AOB较NOB具有更高的活性恢复速率上。此外,好氧饥饿能够快速杀死丝状细菌,迅速改善膨胀污泥的沉降性能,使污泥的SVI由170 ml·g^-1快速下降到30 ml·g^-1。胞外聚合物(extracellular polymeric substances, EPS)和溶解性微生物产物(soluble microbial products, SMP)能够相互转化,并为饥饿污泥提供一定的碳源和能源,保证了细菌在饥饿环境中长期的细胞维持。     

Thermogravimetric characteristics of aerobic granules developed at different salinities

BACKGROUND: Aerobic granular sludge is a self‐immobilization biotechnology for wastewater treatment. The thermogravimetric characteristics of aerobic granules were investigated in this study. RESULTS: The strongly physically bound water in granules that developed at a salinity of 1% (in reactor R1) and 5% (in reactor R2) were 5% and 3%, respectively. In addition, the extracellular polymer substances (EPS) affected the bound water more significantly at a low salinity than a higher one. Based on thermogravimetric analysis (TGA), granules that developed at low salinity (such as 1% in R1) exhibited a rich diversity of organic components, and higher total EPS concentrations, inferred from the ratios of volatile solids to total solids. Additionally, the maximum weight loss rates of the granules in all reactors occurred at a temperature of around 250 °C and the endothermic peaks shifted to a relatively low temperature with increasing salinity regardless of the existence of EPS. CONCLUSION: Increasing the salinity in the substrates slightly decreased the bound water fraction in granules and reduced the richness of the granule components as well as the biodiversity. This study provides detailed information on the components of aerobic granule. Copyright © 2007 Society of Chemical Industry     

Aerobic granules for low‐strength wastewater treatment: formation,structure, and microbial community

BACKGROUND: To validate the possibility of aerobic granulation at a lower organic loading rate (OLR) than 2 kg COD m^?3 day^?1 (GS 1) in a sequencing batch reactor (SBR), the formation, structure, and microbial community of granular sludge (GS) were investigated. RESULTS: The overall experimental process involved the following stages: acclimation, granulation, maturation, and stabilization. The optical microscopic showed the structural changes from fluffy activated sludge (AS) to GS and scanning electron microscope (SEM) examination revealed that GS 1 was irregular filamentous aggregates composed mainly of various filamentous species, while the aerobic granules cultivated at OLR 1.68–4.20 kg COD m^?3 day^?1 (GS 2) was mycelial pellets consisting of fungi and filamentous microorganisms. A Biolog Ecoplate analysis indicated that significant differences existed between the microbial community structure and the substrate's utilization of AS and different GS samples. CONCLUSION: GS 1 was achieved and different from GS 2 in the formation, structure, and microbial community. Aerobic granulation with low strength wastewater is of importance for the full‐scale application of this technology. Copyright © 2009 Society of Chemical Industry     

粒径对番茄酱废水好氧颗粒污泥性能的影响

颗粒污泥的培养基质、粒径影响着颗粒的生物活性、传质效应及菌群的结构分布和协同竞争关系,进而影响出水效果.用番茄酱废水在序批式活性污泥法(SBR)反应器中成功培养颗粒污泥并稳定维持185 d,筛分出4种粒径范围的颗粒进行同步序批式实验,考察污泥特性及其对番茄酱生产废水的除污效能.结果表明,0.45～1.00 mm的颗粒形...