Download or read book Anaerobic Digester Fluid Rheology and Process Efficiency written by Luka Šafari? and published by Linköping University Electronic Press. This book was released on 2019-04-08 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the anthropogenic greenhouse gas emissions continue imposing stress on our environment, it is becoming increasingly important to identify and implement new renewable technologies. Biogas production through anaerobic digestion has a great potential, since it links waste treatment with extraction of renewable energy, enabling circular bio-economies that are vital for a sustainable future. For biogas to have an important role as a renewable energy carrier in society, the scale of its production will need to be increased substantially. New substrates need to be introduced along with raising organic loading rates of the reactors to increase the rate of biogas production. This contributes to challenges in maintaining process stability, thus increasing the risk for process disturbances, including problems that were not commonly encountered before. These difficulties may be particularly pronounced when a broad range of new, largely untested substrates are introduced, leading to an increased heterogeneity of organic material entering the reactors. In the case of currently the most common reactor type; the continuous stirred-tank biogas reactor (CSTBR); such problems may include shifts in rheology (i.e. fluid behaviour) of the anaerobic digester sludge. This may lead to increased energy consumption and decreased digester mixing efficiencies, which in turn may lead to inefficient biogas processes, ultimately decreasing the economic and environmental viability of biogas production. Much is still unknown regarding how rheology shifts happen in biogas reactors, particularly when it comes to what role the substrate plays in rheological dynamics, as compared to the microbial community during varying levels of biogas process stability. This thesis elucidates the interactions between substrate type, microbial community and its metabolic activity, and anaerobic sludge rheology. A number of sludge samples from mesophilic and thermophilic CSTBRs digesting a broad range of substrates was analysed for their rheology. The specific effects of individual substrate types on CSTBR sludge rheology and the resulting implications for stirring power requirements and mixing efficiency were investigated. In order to also asses to which extent the microbial metabolism affects rheology at different levels of process disturbance, an experiment with a trace-element-induced inhibition of specific metabolic pathways under mesophilic reactor conditions was performed. This was used to identify the sequence of different interactions that occur in the reactor after the process begins to fail, and to evaluate how these interactions link to changes in digester sludge rheology. Finally, a case study of a disturbed thermophilic anaerobic digestion process was performed, including the monitoring of the response of rheology in relation to process stability, which was modified by changing trace element concentrations. The use of artificial substrate without polymeric compounds in both cases allowed for an evaluation of effects of the microbial community and its metabolic products on rheology without including the effects of complex substrates. The results showed that substrate type has a large effect on how different process parameters correlate with fluid behaviour. This was particularly apparent in the case of total solids and total volatile solids, which correlated well with rheological parameters for samples from reactors digesting agricultural waste, sewage sludge, paper mill waste, or food waste, but not for mesophilic co-digesters. Among the different substrates investigated, food waste was generally observed to lead to the highest limit viscosities (i.e. apparent viscosities at high shear rates, where it becomes linear and constant) of the anaerobic sludge, while digestion of paper mill waste and thermophilic co-digestion led to some of the lowest. No fluid type could be clearly coupled to a specific substrate, but it could be observed that increased solids content could generally be associated with more complex, non-Newtonian rheological behaviour. The differences in fluid characteristics between reactors corresponded to large differences in modelled stirring power requirements and mixing efficiency. The results indicated that fluids with high values of rheological parameters, such as the consistency index (K) or yield stress (?0), would likely require more power or an adapted stirring system to achieve complete mixing. The substrates generally contributed more to the rheology characteristics of the anaerobic sludge than microbial cells on their own. Trace element-induced process disturbance initially led to the inhibition of specific microbial groups among methanogenic archaea or their syntrophic partners, which later escalated to broader inhibition of many microbial groups due to the accumulation of fermentation products. This resulted in microbial cell washout with a corresponding decrease of the contribution of the cells to anaerobic sludge rheology. A recovery of the thermophilic anaerobic digestion process was possible after the supplementation of selenium and tungsten was increased, resulting in increased propionate turnover rates, growing cell densities, and higher viscosity. Major shifts in the methanogenic community were observed, corresponding to the level of process stability. It could be concluded based on these experiments that the specific effect of microbial cells and their activity on sludge rheology were linked to cell density, which corresponded to process stability. A conceptual scheme was developed based on the studies in this thesis, defining complex interactions between substrate, microbial metabolism, and anaerobic sludge rheology in biogas processes. The possible causes of rheology shifts are visualised and discussed. Med anledning av att antropogena utsläpp av växthusgaser fortsätter att påverka vår miljö negativt, blir det allt viktigare att identifiera och implementera förnybara teknologier. Biogasproduktion, genom anaerob rötning, bidrar till att sammanlänka avfallshantering med förnybar energiomvandling samt möjliggör för cirkulära bioekonomier, avgörande för en hållbar framtid. För att biogas ska utgöra en central roll som förnybar energibärare i samhället måste omfattningen av dess produktion ökas avsevärt. Nya substrat behöver introduceras, samtidigt som den organiska belastningen i existerande biogasreaktorer ökas, med syfte att öka produktionshastigheten. Detta bidrar emellertid till utmaningar avseende att upprätthålla processtabilitet, med ökad risk för processtörningar, inklusive nya typer av problem. Dessa svårigheter kan vara särskilt uttalade när nya, i stort sett otestade substrat, introduceras, vilket leder till ökad heterogenitet av organiskt material till reaktorerna. I tankreaktorer med omrörning (CSTBR), som i nuläget är den vanligast förekommande reaktortypen, kan sådana processförändringar innebära förändringar i reologiska egenskaper hos rötvätskor. Detta kan i sin tur leda till ökad energiförbrukning och lägre omrörningseffektivitet, vilket kan försämra biogasprocessens effektivitet samt bidra till minskad ekonomisk avkastning och minskade miljömässiga vinster. Det råder fortfarande oklarheter gällande reologiska förändringar av rötkammarmaterial i biogasreaktorer, särskilt med avseende på val av substrat i jämförelse med mikroorganismernas roll under varierade betingelser av processtabilitet. Denna avhandling belyser interaktioner mellan typ av substrat, mikrobiella samhällen och deras metaboliska aktivitet och reologiska egenskaper av rötslam. Reologisk karaktärisering av rötvätskor från mesofila och termofila CSTBRs, som rötade ett brett spektrum av substrat, genomfördes. De specifika effekterna av individuella substrattyper på korresponderande rötvätskors reologiska egenskaper och dess implikationer för omrörning undersöktes. För att även kunna bedöma i vilken utsträckning den mikrobiella metabolismen inverkar på rötvätskors reologi, vid olika nivåer av processtörning, genomfördes en fallstudie med spårelement-inducerad inhibering av specifika metaboliska vägar, under mesofila reaktorbetingelser. Denna studie användes för att identifiera sekvensen av olika interaktioner som uppträder i reaktorn när processtörningar uppstår och för att utvärdera hur dessa interaktioner kopplar till förändringar i slamreologi. Slutligen genomfördes en fallstudie av en termofil biogasprocess innefattande karaktärisering av reaktormaterialets reologi i respons till förändringar i processtabilitet orsakad av förändrade spårelementkoncentrationer. I båda dessa fallstudier, möjliggjorde användningen av ett artificiellt substrat utan komplexa polymerer, att mikrobiella effekter på förändringar i rötvätskans reologi kunde studeras frånkopplat effekter av komplexa substrat. Resultaten visade att substrattyp har stor inverkan på hur olika processparametrar korrelerar med rötvätskors reologiska egenskaper. Detta var särskilt tydligt med avseende på andelen totala respektive organiska fasta ämnen, vilka korrelerade väl med reologiska parametrar för rötvätskor från reaktorer som rötade jordbruksrester, avloppsslam, avfall från pappersbruk, respektive matavfall, men ej för rötvätskor från mesofila samrötningsanläggningar. Av de undersökta substrattyperna bidrog rötning av matavfall generellt till anaerobt slam med högst uppmätta värdena för gränsviskositet (dvs när viskositeten blir linjär och konstant vid ökade skjuvhastigheter), medan rötning av avfall från pappersbruk respektive termofil samrötning av olika substrat bidrog till de lägsta värdena för gränsviskoistet. Ingen reologisk vätsketyp kunde tydligt kopplas till en specifik substrattyp, men ökad mängd torrsubstans i rötvästkan kunde generellt associeras med komplexa, icke-newtonska, flödesegenskaper. Skillnaderna i flödesegenskaper motsvarade stora skillnader i behov av omrörningskraft och omrörningseffektivitet. Resultaten indikerade att rötvätskor med höga reologiska värden, exempelvis för konsistensindex (K) eller flytgräns (?0), sannolikt kräver mer energi eller ett anpassat system för effektivare omrörning. Generellt bidrog substratet mer till rötvätskans reologiska egenskaper än de mikrobiella cellerna på egen hand. Inducerad spårämnesbrist i genomfört reaktorförök ledde i början till en hämning av specifika mikrobiella grupper inom metanogena arkéer och deras syntrofa partners, vilket i sin tur bidrog till en bredare hämning av flera mikrobiella grupper orsakad av ackumulering av olika fermentationsprodukter. Detta resulterade i ursköljning av cellbiomassa vilket i sin tur minskade deras effekt på slammets reologiska egenskaper. En återhämtning av den termofila biogasprocessen var möjlig efter ökade tillsatser av spårelementen selen och volfram, vilket resulterade i snabbare omsättning av propionsyra, förhöjd celldensitet och viskositet. Stora förändringar observerades samtidigt inom det metanogena samhället, vilka var kopplade till olika nivåer av processtabilitet. Den specifika effekten av mikroorganismerna och deras aktivitet med avseende på slammens reologiska egenskaper var kopplad till celldensitet, vilket motsvarade processtabiliteten. Ett konceptuellt schema utvecklades baserat på resultat av beskrivna studier för att visualisera komplexa interaktioner mellan substrat, mikrobiell metabolism, och reologi av anaerobt slam i biogasprocesser. De möjliga orsakerna till reologiska förändringar visualiseras och diskuteras.

Download or read book Anaerobic Digestion Model No 1 ADM1 written by IWA Task Group for Mathematical Modelling of Anaerobic Digestion Processes and published by IWA Publishing. This book was released on 2002-02-01 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: The IWA Task Group for Mathematical Modelling of Anaerobic Digestion Processes was created with the aim to produce a generic model and common platform for dynamic simulations of a variety of anaerobic processes. This book presents the outcome of this undertaking and is the result of four years collaborative work by a number of international experts from various fields of anaerobic process technology. The purpose of this approach is to provide a unified basis for anaerobic digestion modelling. It is hoped this will promote increased application of modelling and simulation as a tool for research, design, operation and optimisation of anaerobic processes worldwide. This model was developed on the basis of the extensive but often disparate work in modelling and simulation of anaerobic digestion systems over the last twenty years. In developing ADM1, the Task Group have tried to establish common nomenclature, units and model structure, consistent with existing anaerobic modelling literature and the popular activated sludge models (See Activated Sludge Models ASM1, ASM2, ASM2d and ASM3, IWA Publishing, 2000, ISBN: 1900222248). As such, it is intended to promote widespread application of simulation from domestic (wastewater and sludge) treatment systems to specialised industrial applications. Outputs from the model include common process variables such gas flow and composition, pH, separate organic acids, and ammonium. The structure has been devised to encourage specific extensions or modifications where required, but still maintain a common platform. During development the model has been successfully tested on a range of systems from full-scale waste sludge digestion to laboratory-scale thermophilic high-rate UASB reactors. The model structure is presented in a readily applicable matrix format for implementation in many available differential equation solvers. It is expected that the model will be available as part of commercial wastewater simulation packages. ADM1 will be a valuable information source for practising engineers working in water treatment (both domestic and industrial) as well as academic researchers and students in Environmental Engineering and Science, Civil and Sanitary Engineering, Biotechnology, and Chemical and Process Engineering departments. Contents Introduction Nomenclature, State Variables and Expressions Biochemical Processes Physicochemical Processes Model Implementation in a Single Stage CSTR Suggested Biochemical Parameter Values, Sensitivity and Estimation Conclusions References Appendix A: Review of Parameters Appendix B: Supplementary Matrix Information Appendix C: Integration with the ASM Appendix D: Estimating Stoichiometric Coefficients for Fermentation Scientific & Technical Report No.13

Download or read book Process Monitoring in Biogas Plants written by Bernhard Drosg and published by . This book was released on 2013 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Current Advances in Anaerobic Digestion Technology written by Marcell Nikolausz and published by MDPI. This book was released on 2021-03-17 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anaerobic digestion (AD) is one of the oldest biotechnological processes and originally referred to biomass degradation under anoxic conditions in both natural and engineered systems. It has been used for decades to treat various waste streams and to produce methane-rich biogas as an important energy carrier, and it has become a major player in electrical power production. AD is a popular, mature technology, and our knowledge about the influencing process parameters as well as about the diverse microbial communities involved in the process has increased dramatically over the last few decades. To avoid competition with food and feed production, the AD feedstock spectrum has constantly been extended to waste products either rich in recalcitrant lignocellulose or containing inhibitory substances such as ammonia, which requires application of various pre-treatments or specific management of the microbial resources. Extending the definition of AD, it can also convert gases rich in hydrogen and carbon dioxide into methane that can substitute natural gas, which opens new opportunities by a direct link to traditional petrochemistry. Furthermore, AD can be coupled with emerging biotechnological applications, such as microbial electrochemical technologies or the production of medium-chain fatty acids by anaerobic fermentation. Ultimately, because of the wide range of applications, AD is still a very vital field in science. This Special Issue highlights some key topics of this research field.

Download or read book Non Newtonian Flow and Applied Rheology written by R. P. Chhabra and published by Elsevier. This book was released on 2011-04-08 with total page 750 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book bridges the gap between the theoretical work of the rheologist, and the practical needs of those who have to design and operate the systems in which these materials are handled or processed. It is an established and important reference for senior level mechanical engineers, chemical and process engineers, as well as any engineer or scientist who needs to study or work with these fluids, including pharmaceutical engineers, mineral processing engineers, medical researchers, water and civil engineers. This new edition covers a considerably broader range of topics than its predecessor, including computational fluid dynamics modelling techniques, liquid/solid flows and applications to areas such as food processing, among others. * Written by two of the world's leading experts, this is the only dedicated non-Newtonian flow reference in print. * Since first publication significant advances have been made in almost all areas covered in this book, which are incorporated in the new edition, including developments in CFD and computational techniques, velocity profiles in pipes, liquid/solid flows and applications to food processing, and new heat/mass transfer methods and models. * Covers both basic rheology and the fluid mechanics of NN fluids ? a truly self-contained reference for anyone studying or working with the processing and handling of fluids

Download or read book Computational Fluid Dynamics written by Adela Ionescu and published by BoD – Books on Demand. This book was released on 2018-02-14 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the result of a careful selection of contributors in the field of CFD. It is divided into three sections according to the purpose and approaches used in the development of the contributions. The first section describes the "high-performance computing" (HPC) tools and their impact on CFD modeling. The second section is dedicated to "CFD models for local and large-scale industrial phenomena." Two types of approaches are basically contained here: one concerns the adaptation from global to local scale, - e.g., the applications of CFD to study the climate changes and the adaptations to local scale. The second approach, very challenging, is the multiscale analysis. The third section is devoted to "CFD in numerical modeling approach for experimental cases." Its chapters emphasize on the numerical approach of the mathematical models associated to few experimental (industrial) cases. Here, the impact and the importance of the mathematical modeling in CFD are focused on. It is expected that the collection of these chapters will enrich the state of the art in the CFD domain and its applications in a lot of fields. This collection proves that CFD is a highly interdisciplinary research area, which lies at the interface of physics, engineering, applied mathematics, and computer science.

Download or read book Post Treatments of Anaerobically Treated Effluents written by Vinay Kumar Tyagi and published by IWA Publishing. This book was released on 2019-06-15 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: The anaerobic process is considered to be a sustainable technology for organic waste treatment mainly due to its lower energy consumption and production of residual solids coupled with the prospect of energy recovery from the biogas generated. However, the anaerobic process cannot be seen as providing the ‘complete’ solution as its treated effluents would typically not meet the desired discharge limits in terms of residual carbon, nutrients and pathogens. This has given impetus to subsequent post treatment in order to meet the environmental legislations and protect the receiving water bodies and environment. This book discusses anaerobic treatment from the perspective of organic wastes and wastewaters (municipal and industrial) followed by various post-treatment options for anaerobic effluent polishing and resource recovery. Coverage will also be from the perspective of future trends and thoughts on anaerobic technologies being able to support meeting the increasingly stringent disposal standards. The resource recovery angle is particularly interesting as this can arguably help achieve the circular economy. It is intended the information can be used to identify appropriate solutions for anaerobic effluent treatment and possible alternative approaches to the commonly applied post-treatment techniques. The succeeding discussion is intended to lead on to identification of opportunities for further research and development. This book can be used as a standard reference book and textbook in universities for Master and Doctoral students. The academic community relevant to the subject, namely faculty, researchers, scientists, and practicing engineers, will find the book both informative and as a useful source of successful case studies.

Download or read book The Microbiology of Anaerobic Digesters written by Michael H. Gerardi and published by John Wiley & Sons. This book was released on 2003-09-19 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anaerobic digestion is a biochemical degradation process that converts complex organic material, such as animal manure, into methane and other byproducts. Part of the author's Wastewater Microbiology series, Microbiology of Anareboic Digesters eschews technical jargon to deliver a practical, how-to guide for wastewater plant operators.

Download or read book Computational Fluid Dynamics Applications in Bio and Biomedical Processes written by Satya Eswari Jujjavarapu and published by Springer Nature. This book was released on 2024-01-17 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers emerging areas in novel design and their hydrodynamic properties relevant to bioreactors, environmental system, electrochemical systems, food processing and biomedical engineering. This book uses an interdisciplinary approach to provide a comprehensive prospective simulation modeling and hydrodynamic study in advanced biotechnological process and includes reviews of the most recent state of art in modeling and simulation of flows in biological process, such as CFD. Written by internationally recognized researchers in the field, each chapter provides a strong introductory section that is useful to both readers currently in the field and readers interested in learning more about these areas.

Download or read book Fossil Energy Update written by and published by . This book was released on 1981 with total page 826 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Membrane Bioreactor Processes written by Seong-Hoon Yoon and published by CRC Press. This book was released on 2015-06-17 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Grasp the Essential Principles of Membrane Bioreactor ProcessesEvolved from the conventional activated sludge (CAS) process, membrane bioreactor (MBR) processes have become the next-generation solution for municipal and industrial wastewater treatment and recycle. Membrane Bioreactor Processes: Principles and Applications explores nearly all the th

Download or read book Computational Fluid Dynamics for Engineers written by Bengt Andersson and published by Cambridge University Press. This book was released on 2011-12-22 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational fluid dynamics, CFD, has become an indispensable tool for many engineers. This book gives an introduction to CFD simulations of turbulence, mixing, reaction, combustion and multiphase flows. The emphasis on understanding the physics of these flows helps the engineer to select appropriate models to obtain reliable simulations. Besides presenting the equations involved, the basics and limitations of the models are explained and discussed. The book combined with tutorials, project and power-point lecture notes (all available for download) forms a complete course. The reader is given hands-on experience of drawing, meshing and simulation. The tutorials cover flow and reactions inside a porous catalyst, combustion in turbulent non-premixed flow, and multiphase simulation of evaporation spray respectively. The project deals with design of an industrial-scale selective catalytic reduction process and allows the reader to explore various design improvements and apply best practice guidelines in the CFD simulations.

Download or read book Solar Energy Update written by and published by . This book was released on 1986 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Comprehensive Biotechnology written by and published by Newnes. This book was released on 2011-08-26 with total page 5304 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of Comprehensive Biotechnology, Six Volume Set continues the tradition of the first inclusive work on this dynamic field with up-to-date and essential entries on the principles and practice of biotechnology. The integration of the latest relevant science and industry practice with fundamental biotechnology concepts is presented with entries from internationally recognized world leaders in their given fields. With two volumes covering basic fundamentals, and four volumes of applications, from environmental biotechnology and safety to medical biotechnology and healthcare, this work serves the needs of newcomers as well as established experts combining the latest relevant science and industry practice in a manageable format. It is a multi-authored work, written by experts and vetted by a prestigious advisory board and group of volume editors who are biotechnology innovators and educators with international influence. All six volumes are published at the same time, not as a series; this is not a conventional encyclopedia but a symbiotic integration of brief articles on established topics and longer chapters on new emerging areas. Hyperlinks provide sources of extensive additional related information; material authored and edited by world-renown experts in all aspects of the broad multidisciplinary field of biotechnology Scope and nature of the work are vetted by a prestigious International Advisory Board including three Nobel laureates Each article carries a glossary and a professional summary of the authors indicating their appropriate credentials An extensive index for the entire publication gives a complete list of the many topics treated in the increasingly expanding field

Download or read book Biomethanization of the Organic Fraction of Municipal Solid Wastes written by J. Mata-Alvarez and published by IWA Publishing. This book was released on 2002-08-31 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biomethanization of the Organic Fraction of Municipal Solid Wastes is a comprehensive introduction to both the fundamentals and the more practical aspects of the anaerobic digestion of organic solid wastes, particularly those derived from households, that is, the organic fraction of municipal solid wastes (OFMSW). It can be used as a textbook for specialized courses and also as a guide for practitioners. In the first part, the book covers the relevant aspects of anaerobic digestion (AD) of organic wastes. The fundamentals and kinetic aspects of AD are reviewed with particular emphasis on the aspects related to solid wastes. This introduction is necessary to have a comprehensive view of the AD process and to understand the practical principles as well as the origin of possible problems arising from the management of the process. Chapter 2 emphasizes the role of kinetics in designing the reactor, paying special attention to existing models, particularly the dynamic ones. Through this introduction, it is intended to facilitate the technology transfer from laboratory or pilot plant experiences to full-scale process, in order to implement improvements in current digesters. Laboratory methods are described for the analysis and optimization of reactor performance, such as methanogenic activity tests or experimental evaluation of the biodegradation kinetics of solid organic waste. The different reaction patterns applied to industrial reactors are outlined. Industrial reactors are classified in accordance with the system they use, pointing out advantages and limitations. Co-digestion, enabling the co-treatment of organic wastes of different origin in a more economically feasible way, is described in detail. Examples of co-digestion are given, with OFMSW as a base-substrate. Finally, full-scale co-digestion plants are discussed. Various types (mechanical, biological, physico-chemical) of pre-treatment to increase the biodegradability, and thus the yields of the process, are reviewed in detail. The use of the fermentation products of anaerobic digesters for biological nutrient removal processes in wastewater treatment plants is described. This constitutes an example of integrated waste management, a field in which both economic and technical advances can be achieved. Balances are given to justify the approach, and a full-scale case study is presented. The important topic of economics and the ecological advantages of the process are emphasized. The use of compost, the integration with composting technology, and advantages over other technologies are detailed in the framework of an environmental impact assessment of biowaste treatment. Finally, the anaerobic digestion of MSW in landfills is reviewed in detail, with emphasis on landfill process enhancement and strategies for its application.

Download or read book Anaerobic digestion in the kraft pulp and paper industry written by Eva-Maria Ekstrand and published by Linköping University Electronic Press. This book was released on 2019-05-07 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: The pulp and paper industry is a large producer of wastewater and sludge, putting high pressure on waste treatment. In addition, more rigorous environmental legislation for pollution control and demands to increase the use of renewable energy have put further pressure on the pulp and paper industry’s waste treatment, where anaerobic digestion (AD) and the production of methane could pose a solution. Kraft pulping makes up 80% of the world production of virgin wood pulp, thus, the wastewaters from this sector represent a large unused potential for methane production. There are three main types of substrates available for AD at pulp and paper mills, the wastewaters, the primary sludge/fibre sludge, and the waste activated sludge. AD treatment of these streams has been associated with several challenges, such as the presence of inhibiting compounds or low degradability during AD. The aim of this thesis was to experimentally address these challenges and potentials, focusing on wastes from kraft mills. Methane potential batch tests showed that many wastewater streams still posed challenges to AD, but the alkaline elemental chlorine-free bleaching stream and the condensate effluents had good methane potentials. Further, the methane potential of kraft mill fibre sludge was high, and co-digestion of kraft mill fibre sludge and waste activated sludge was feasible in stirred tank reactors with sludge recirculation. By increasing the organic loading in a pilot-scale activated sludge facility and thereby lowering the sludge age, the degradability of the waste activated sludge was improved. The higher wastewater treatment capacity achieved by this method provides an opportunity for the mills to increase their pulp and paper production. Further, by dewatering the digestate after AD and returning the liquid to the activated sludge treatment, costs for nutrient supplementation can be reduced. In conclusion, the thesis shows that AD of wastes from the kraft pulp and paper industry was feasible and carried many benefits regarding the generation of methane as a renewable energy carrier, improved wastewater treatment and reduced costs. Different strategies on how AD may be implemented in the kraft pulp and paper industry were formulated and discussed. Produktionen av pappers- och massa genererar stora mängder avloppsvatten, vilket ställer höga krav på en effektiv vattenrening. Därtill har skärpta regler för utsläpp till vatten och luft tillsammans med en ökad efterfrågan på användning av förnyelsebar energi ytterligare ökat trycket på vattenreningen inom pappers-och massaindustrin, där anaerob nedbrytning med metanproduktion som följd skulle kunna utgöra en lösning. Produktionen av sulfatmassa (en kemiskt kokad pappersmassa) utgör 80% av den globala nyproduktionen av massa, vilket innebär att avloppsvatten från denna sektor representerar en stor outnyttjad potential för metanproduktion. Det finns huvudsakligen tre typer av substrat tillgängliga för rötning vid pappers- och massabruk, avloppsvatten, primärslam/fiberslam, och aktivt slam/överskottsslam. Flera utmaningar är kopplade till anaerob nedbrytning av dess strömmar, såsom förekomst av inhiberande ämnen eller låg nedbrytbarhet. Målet med avhandlingen var att bemöta dessa utmaningar, med ett särskilt fokus på behandling av avloppsströmmar från sulfatbruk. Metanpotentialtester visade att många av avloppsvattnen fortfarande var svåra att behandla med anaerob nedbrytning, men att alkaliska blekeriströmmar och kondensatströmmar vid sulfatbruk visade lovande metanpotentialer. Massafiber från sulfatoch sulfitbruk uppvisade höga metanpotentialer, och en stabil kontinuerlig samrötning av fiberslam och aktivt slam från sulfatbruk uppnåddes vid hög organisk belastning och låg hydraulisk uppehållstid i omrörda tankreaktorer med slamåterföring. Resultaten visade vidare att den låga nedbrytbarheten hos aktivt slam kunde bemötas genom att sänka slamåldern i den luftade anläggningen, med högre metanpotential i slammet som följd. Via denna metodik erhålles en högre vattenreningskapacitet, vilket innebär att bruken kan öka sin produktion av papper och massa. Dessutom kan rötresten avvattnas och den kvarvarande vätskan återföras till den luftade anläggningen för att minska behovet av näringstillsatser. Sammanfattningsvis visar avhandlingen att anaerob nedbrytning av avloppsströmmar från sulfatbruk var fullt möjlig och innebar många fördelar, i form av metanproduktion, förbättrad kapacitet för vattenrening och reducerade kostnader jämfört med dagens teknik. Olika möjligheter för implementering av anaerob teknik vid sulfatbruk har också formulerats och diskuterats.

Download or read book Reduction Modification and Valorisation of Sludge written by Azael Fabregat and published by IWA Publishing. This book was released on 2011-03-15 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: The adoption of the Urban Waste Water Treatment Directive requires sewage sludge to be subsequently treated and the Sewage Sludge Directive regulates the uses and properties of stabilised sludge for being either recycled or disposed. Both directives drive specific actions in two complementary ways. Reduction, Modification and Valorisation of Sludge aims at developing strategies for the disposal and reuse of waste sludge. It aims to develop several processes for reducing both amount and toxicity of sludge, with simultaneous transformation into green energy vectors such as methane or hydrogen. Mesophilic and mainly thermophilic and autothermophilic conditions are explored as classical alternatives for sludge stabilisation, assuring sanitary conditions of the treated sludge. Valuable materials are obtained from sludge, such as activated carbons, which are used in conventional adsorption processes and in innovative advanced oxidation processes. Guidelines are provided for technology selection in agreement with the geographic, economic and technical characteristics of the sewage plants, demonstration of the feasibility of new applications for the sewage sludge, manufacturing of activated carbon from sludge sewage as innovative recycling of sludge waste, and a deep understanding of the methods involved. Visit the IWA WaterWiki to read and share material related to this title: http://www.iwawaterwiki.org/xwiki/bin/view/Articles/GLOBALATLASOFEXCRETAWASTEWATERSLUDGEANDBIOSOLIDSMANAGEMENTMOVINGFORWARDTHESUSTAINABLEANDWELCOMEUSESOFAGLOBALRESOURCE