Anaerobic Reactor Design Concepts for the Treatment of Domestic Wastewater

Since the earlier anaerobic treatment systems, the design concepts were improved from classic reactors like septic tanks and anaerobic ponds, to modern high rate reactor configurations like anaerobic filters, UASB, EGSB, fixed film fluidized bed and expanded bed reactors, and others. In this paper, anaerobic reactors are evaluated considering the historical evolution and types of wastewaters. The emphasis is on the potential for application in domestic sewage treatment, particularly in regions with a hot climate. Proper design and operation can result in a high capacity and efficiency of organic matter removal using single anaerobic reactors. Performance comparison of anaerobic treatment systems is presented based mostly on a single but practical parameter, the hydraulic retention time. Combined anaerobic reactor systems as well as combined anaerobic and non-anaerobic systems are also presented.     

典型有机固废厌氧消化微生物研究现状与发展方向

经过人工富集和驯化的兼性和严格厌氧微生物是厌氧消化工艺的核心。不同厌氧消化体系中存在的问题大多可以通过改变微生物群落的代谢活性来得到有效改善。得益于微生物组学检测技术的快速发展,对厌氧消化系统中微生物多样性的认识获得了极大的拓展,同时在微生物类群间、微生物与环境的互作关系研究方面也取得了一系列新的进展。然而,有机固废厌氧消化系统中,各种微生物以及微生物和物质的相互作用构成了更为复杂的代谢网络,所以目前对这些互作关系的解析尚不完善。本文重点关注了厌氧消化过程中的典型菌群互作关系,阐述了典型有机固废厌氧消化系统中存在的问题及微生物在其中发挥的作用,最后,立足于现有组学技术推动的微生物组研究进展,对未来有机固废厌氧消化系统微生物组的研究提出展望。     

小鼠盲肠内容物中正常菌群的分离和定量

本文报道了采用厌氧培养技术,从小鼠盲肠内容物中分离到6株严格厌氧和兼性厌氧菌。鉴定为拟杆菌、乳酸杆菌、双歧杆菌、难辨梭菌、粪链球菌和大肠扦菌。它们在小鼠盲肠内容物的正常菌群中占优势,含菌量与国外文献中报告的相似。     

Biological nutrients removal from the supernatant originating from the anaerobic digestion of the organic fraction of municipal solid waste

Abstract

This study critically evaluates the biological processes and techniques applied to remove nitrogen and phosphorus from the anaerobic supernatant produced from the treatment of the organic fraction of municipal solid waste (OFMSW) and from its co-digestion with other biodegradable organic waste (BOW) streams. The wide application of anaerobic digestion for the treatment of several organic waste streams results in the production of high quantities of anaerobic effluents. Such effluents are characterized by high nutrient content, because organic and particulate nitrogen and phosphorus are hydrolyzed in the anaerobic digestion process. Consequently, adequate post-treatment is required in order to comply with the existing land application and discharge legislation in the European Union countries. This may include physicochemical and biological processes, with the latter being more advantageous due to their lower cost. Nitrogen removal is accomplished through the conventional nitrification/denitrification, nitritation/denitritation and the complete autotrophic nitrogen removal process; the latter is accomplished by nitritation coupled with the anoxic ammonium oxidation process. As anaerobic digestion effluents are characterized by low COD/TKN ratio, conventional denitrification/nitrification is not an attractive option; short-cut nitrogen removal processes are more promising. Both suspended and attached growth processes have been employed to treat the anaerobic supernatant. Specifically, the sequencing batch reactor, the membrane bioreactor, the conventional activated sludge and the moving bed biofilm reactor processes have been investigated. Physicochemical phosphorus removal via struvite precipitation has been extensively examined. Enhanced biological phosphorus removal from the anaerobic supernatant can take place through the sequencing anaerobic/aerobic process. More recently, denitrifying phosphorus removal via nitrite or nitrate has been explored. The removal of phosphorus from the anaerobic supernatant of OFMSW is an interesting research topic that has not yet been explored. At the moment, standardization in the design of facilities that treat anaerobic supernatant produced from the treatment of OFMSW is still under development. To move toward this direction, it is first necessary to assess the performance of alternative treatment options. It study concentrates existing data regarding the characteristics of the anaerobic supernatant produced from the treatment of OFMSW and from their co-digestion with other BOW. This provides data documenting the effect of the anaerobic digestion operating conditions on the supernatant quality and critically evaluates alternative options for the post-treatment of the liquid fraction produced from the anaerobic digestion process.     

麻鸭肠道无芽胞厌氧菌定性、定量和定位研究

本研究采用气、液相色谱分析法(Gas-Liquid Chromatography,GLC)分析细菌代谢产物,结合微生物学鉴定和微量快速生化反应,在我国首次定量测定了麻鸭小肠、大肠每克内容物4种厌氧菌的菌数,初次确定在小肠有卵形类杆菌、发酵乳杆菌、两歧双歧杆菌、空肠弯曲杆菌4个种;在大肠有卵形类杆菌、多形类杆菌、解脲类杆菌、发酵乳杆菌、干酪乳杆菌、植物乳杆菌、短双歧杆菌、空肠弯曲杆菌和粪弯曲杆菌9个种。类杆菌和乳杆菌等是麻鸭肠道正常微生物群。     

Paper Chromatography as an Adjunct in the Identification of Anaerobic Bacteria

Modified paper chromatography procedures for the analysis of fatty acids produced by anaerobic bacteria are described. Both ethylamine and hydroxylamine derivatives of fatty acids were prepared from inoculated anaerobic culture broth. The derivatives were spotted on chromatography paper and developed with appropriate solvents. Paper chromatography is a valuable alternative to gas liquid chromatography as an ancillary procedure in the identification of anaerobic bacteria in the clinical bacteriology laboratory.     

Investigation of the kinetics of anaerobic metabolism by analysis of the performance of elite sprinters

The principal motivation for the present work was the study of the kinetics of anaerobic metabolism. A new mathematical model of the bioenergetics of sprinting, incorporating a three-equation representation of anaerobic metabolism, is developed. Results computed using the model are compared with measured data from the mens' finals of the 100m event at the 1987 World Championships. The computed results closely predict the overall average performance of the competitors over the course of the entire race. Further calculations show the three-equation model of anaerobic metabolism to be a significant improvement over the previous one-equation model. Representative values of time constants that govern the rate of anaerobic energy release have been determined for elite male athletes. For phosphocreatine utilisation, values for lambda(2)=0. 20s(-1) and psi(2)=3.0s(-1) are consistent with data previously reported in the literature. New values of lambda(3)=0.033s(-1) and psi(3)=0.34s(-1) are proposed as offering an improved representation of the kinetics of oxygen-independent glycolysis. For the first time, tentative values for the time constants of ATP utilisation, lambda(1)=0.9s(-1) and psi(1)=20s(-1), are suggested. The maximum powers developed during sprinting by oxygen-independent glycolysis, PCr utilisation and endogenous ATP utilisation were calculated as 34. 1, 30.1 and 16.6Wkg(-1), respectively, with an overall maximum anaerobic power of 51.6Wkg(-1). Sample calculations show the mathematical model can be used in principle to derive data on the kinetics of anaerobic metabolism of individual athletes.     

Post-Treatment Options for the Anaerobic Treatment of Domestic Wastewater

This paper focuses on the post-treatment options for the anaerobic treatment of domestic wastewater. Initially, the main limitations of anaerobic systems regarding carbon, nutrients and pathogen removal are presented. In sequence, the advantages of combined anaerobic/aerobic treatment and the main post-treatment options currently in use are discussed, including the presentation of flowsheets and a comparison between various post-treatment systems. Lastly, the paper presents a review of emerging options and possible improvements of current post-treatment alternatives.     

The functional state of children from 9 to 10 years of age under the conditions of intense informational load and physical working capacity

Three-way ANOVA has shown that the functional state (FS) of children from 9 to 10 years of age (n = 91) under intense informational load is significantly influenced by the aerobic and anaerobic components of physical working capacity and their interaction. It has been found that 4 to 21% of the total variation of the studied FS indices are related to the bioenergetic resources of the body. It has been shown that the high levels of development of the aerobic and anaerobic glycolytic capacities are associated with the optimal changes in the FS under the conditions of intense informational load. At the same time, the interaction of the aerobic and anaerobic glycolytic components of physical working capacity exerts the most significant influence on the productivity and “psychophysiological cost” of intellectual activity. The high anaerobic glycolytic and anaerobic alactate capacities proved to have opposite functional effects. The former contribute to a decrease in excessive autonomic reactivity under the conditions of intense work and diminution of trait anxiety; the latter, on the contrary, determine hypermobilization of the system of autonomic support of activity. The results suggest that a combined use of rational proportions of physical loads of the aerobic, anaerobic glycolytic, and anaerobic alactate types will provide efficient control of children’s FS under the conditions of intense intellectual activity.     

Comparison of the performance of one stage and two stage sequential anaerobic-aerobic biological processes for the treatment of reactive-azo-dye-containing synthetic wastewaters

In the present study the performance of anaerobic-aerobic one and two stage processes for the biological treatment of synthetic wastewaters containing Reactive Black 5 (RB5) were studied and compared with each other. In both processes the majority of colour removal by biodegradation occurred under anaerobic environment. The colour change under aerobic conditions was correlated with extent of anaerobic decolourisation in the preceding phase/stage of the process. Partial mineralisation of the anaerobic dye metabolites, roughly to the same extent, was achieved aerobically in both one stage and two stage processes. The majority of COD was removed in the anaerobic stage for two stage processes and aerobic stage in one stage processes. In one stage processes, the exposure of anaerobic sludge to alternating anaerobic-aerobic environment decreased anaerobic decolourisation efficiency and COD removal; when employing activated sludge, the same exposure enhanced anaerobic substrate utilisation whereas the effect on the anaerobic decolourisation efficiency depended on RB5 concentration. The comparative performance of one and two stage processes in terms of overall dye decolourisation depended on RB5 concentration. Both types of processes brought about similar overall COD removal. Increase in RB5 concentration, in the range studied, resulted in decrease in overall COD removal for both processes.     

Anaerobic microflora of the female reproductive tract

The microflora of the female reproductive tract is very diverse and plays an important role in both normal and pathological states. The data on the mechanisms of colonization resistance which involve the vaginal microbios (the production of H2O2, organic acids, bacteriocin-like substances, competition for adhesion sites) are presented. The data on the role of individual antagonistically active substances of anaerobic bacteria in suppressing gonococci, fungi, microorganisms, associated with bacterial vaginosis, etc. are given. The leading role of anaerobic microorganisms in the appearance of microecological disturbances, including bacterial vaginosis, is emphasized. The role of the pathogenic properties of anaerobic bacteria for the development of different pathological processes, such as premature birth, postnatal and postoperative purulent septic diseases, inflammation of pelvic organs, cancer of the neck of uterus, is discussed.     

Inhibition of the anaerobic digestion process by linear alkylbenzene sulfonates

Linear Alkylbenzene Sulfonates (LAS) are the most widely used synthetic anionicsurfactants. They are anthropogenic, toxic compounds and are found in the primarysludge generated in municipal wastewater treatment plants. Primary sludge is usuallystabilized anaerobically and therefore it is important to investigate the effect of thesexenobiotic compounds on an anaerobic environment. The inhibitory effect of LinearAlkylbenzene Sulfonates (LAS) on the acetogenic and methanogenic step of theanaerobic digestion process was studied. LAS inhibit both acetogenesis from propionate and methanogenesis from acetate and hydrogen and it is shown that the propionate-utilising bacteria are more sensitive to the presence of LAS than the acetoclastic methanogens. It has been proven that the inhibition intensity depends on the solids concentration and thus the term ``biomass specific LAS concentration' has been introduced in order to describe the phenomenon better. Conclusively, it is believed that the inhibitory effect of LAS is the main reason that anaerobic microbial enrichments on LAS have not been succeeded yet. Also, the inhibition caused by LAS on the acetogenic and methanogenic step of the anaerobic digestion process should be seriously taken into consideration when wastewater from a surfactant producing industry is to be treated biologically or enter a municipal wastewater treatment plant that employs anaerobic technology. The upper allowable biomass specific LAS concentration should be 14 mg LAS (gVSS)^-1.     

Comparison of ciliate communities in the anoxic hypolimnia of three lakes: general features and the influence of lake characteristics

The ciliate communities and their food sources were investigatedin the anoxic hypolimnia of three lakes with differing waterchemistry. Bacterial biomass and, as a result, the biomass ofbactenvorous ciliates were correlated with lake trophy. Additionally,high sulfate and sulfide concentrations led to high bacterialbiomass of sulfate reducers and anaerobic phototrophic and heterotrophicbacteria, which in turn sustained large ciliate populations.The anaerobic ciliate communities of the lakes shared many characteristics.They were comprised of the same or closely related species;this was attributed to a low diversity of food sources. Ciliateto prey biomass ratios were 1.2–3.8% which is consistentwith a low theoretical growth efficiency of anaerobic metabolism.Grazing pressure on anaerobic ciliates by metazoa was insignificant.In all three lakes, ciliate populations showed distinct verticalnon-random distribution patterns which were often correlatedwith the distribution of the corresponding food sources. Itis suggested that the microbial communities in anoxic waterbodies are largely influenced by few common environmental conditionsand are therefore often inhabited by similarly structured ciliatecommunities.     

厌氧真菌生态作用及其分子生物学研究进展

厌氧真菌是瘤胃内重要的纤维降解菌,在瘤胃功能的发挥中起重要作用。目前对厌氧真菌纤维降解能力的研究较多,主要集中于对厌氧真菌纤维降解酶如纤维素酶、木聚糖酶等的研究。在瘤胃中,厌氧真菌对粗纤维的降解是其和瘤胃内其他微生物共同作用的结果,因此,瘤胃内厌氧真菌与他微生物之间相互关系的研究越来越受到重视。现代分子生物学技术的发展有利于更深入和透彻的研究厌氧真菌,利用18S rRNA、RFLPI、TS1等分子生物学方法对厌氧真菌进行系统学及进化研究成为热点。     

The place of molecular genetic methods in the diagnostics of human pathogenic anaerobic bacteria. A minireview

Anaerobic infections are common and can cause diseases associated with severe morbidity, but are easily overlooked in clinical settings. Both the relatively small number of infections due to exogenous anaerobes and the much larger number of infections involving anaerobic species that are originally members of the normal flora, may lead to a life-threatening situation unless appropriate treatment is instituted. Special laboratory procedures are needed for the isolation, identification and susceptibility testing of this diverse group of bacteria. Since many anaerobes grow more slowly than the facultative or aerobic bacteria, and particularly since clinical specimens yielding anaerobic bacteria commonly contain several organisms and often very complex mixtures of aerobic and anaerobic bacteria, considerable time may elapse before the laboratory is able to provide a final report. Species definition based on phenotypic features is often time-consuming and is not always easy to carry out. Molecular genetic methods may help in the everyday clinical microbiological practice in laboratories dealing with the diagnostics of anaerobic infections. Methods have been introduced for species diagnostics, such as 16S rRNA PCR-RFLP profile determination, which can help to distinguish species of Bacteroides, Prevotella, Actinomyces, etc. that are otherwise difficult to differentiate. The use of DNA-DNA hybridization and the sequencing of special regions of the 16S rRNA have revealed fundamental taxonomic changes among anaerobic bacteria. Some anaerobic bacteria are extremely slow growing or not cultivatable at all. To detect them in special infections involving flora changes due to oral malignancy or periodontitis, for instance, a PCR-based hybridization technique is used. Molecular methods have demonstrated the spread of specific resistance genes among the most important anaerobic bacteria, the members of the Bacteroides genus. Their detection and investigation of the IS elements involved in their expression may facilitate following of the spread of antibiotic resistance among anaerobic bacteria involved in infections and in the normal flora members. Molecular methods (a search for toxin genes and ribotyping) may promote a better understanding of the pathogenic features of some anaerobic infections, such as the nosocomial diarrhoea caused by C. difficile and its spread in the hospital environment and the community. The investigation of toxin production at a molecular level helps in the detection of new toxin types. This mini-review surveys some of the results obtained by our group and others using molecular genetic methods in anaerobic diagnostics.     

Nucleic acid relationships among the anaerobic mycoplasmas

The genetic relatedness between twelve selected strains among four distinct serovars of anaerobic mycoplasmas was studied using [3H]DNA-DNA hybridization, and the results were compared with data obtained from biochemical and serological tests. Radiolabelled DNA probes were prepared from five strains representing four serovars. Based on the homology results, the anaerobic mycoplasmas can be divided into five distinct groups representing five distinct species and two distinct genera. There are two species in the Anaeroplasma bactoclasticum serovar 1 group represented by strains JR and A-2, one species in serovar 2, one species in A. abactoclasticum serovar 3 and one among the unclassified serovar 4 anaerobic mycoplasmas. The probe to nonsterol-requiring strain 161 of serovar 4 showed no homology with any of the established nonsterol-requiring Acholeplasma species DNAs, or with Mycoplasma hominis DNA, or with avian DNA which served as a negative control. There was good correlation between the phenotypic and genotypic properties of the five distinct anaerobic mycoplasma species but the results indicate that phenotypic properties are not always adequate for speciation of the anaerobic mycoplasmas.     

导电碳颗粒促进污泥厌氧消化及微生物种间电子传递的研究进展

添加导电碳颗粒能够促进厌氧消化过程稳定性、底物降解率以及产沼气品质的同步提高。本文总结了以活性炭和生物炭为代表的导电碳颗粒对城市污泥厌氧消化的影响,探讨了导电碳颗粒促进城市污泥厌氧消化的机理,阐述了导电碳颗粒介导的微生物直接种间电子传递(Directinterspecies electrontransfer,DIET)在强化污泥厌氧消化中的作用机制,分析了复杂厌氧消化体系中微生物DIET互营关系的研究现状,同时对导电碳颗粒的物理化学特性及其对污泥厌氧消化产甲烷的影响进行了分析,最后对未来导电碳颗粒促进城市污泥厌氧消化的研究进行了展望。