As a part of a large project at Norrmejerier, a biogas production plant has been constructed at Umeå Dairy. In this plant wastewater, residual milk and whey are decomposed and biogas is produced. The biogas is burned in a steam boiler. The biogas plant is designed as an anaerobic contact process, with sludge separation and recirculation by a clarifier. The fat in the substrate is treated in a separate reactor. The purpose of this study is to evaluate the design and start-up of this biogas production plant. Further, the interaction with the contractor responsible for construction and start-up is evaluated. The plant is generally well designed, the process conditions are suitable and the objectives are realistic. However, the seed sludge is unsuitable and the time plan is too optimistic. At the end of the period of this study, the plant was running and all central components are performing as intended. Still, the objectives have not been reached. This is mainly attributed to the poor quality of the seed sludge. The management of the plant and the interaction with the contractor has generally been good. Most problems that arose were of typical start-up nature. Others were due to insufficient planning or lack of communication. Further, several design flaws were identified during start-up. Washout of sludge has been one of the most significant drawbacks during start-up. This inconvenience seems to be the result of improper seed sludge and a too hasty increase of the organic loading rate. / Norrmejerier har som en del av ett större projekt låtit uppföra en anläggning för biogasproduktion vid Umeå mejeri. I anläggningen, som är utformad som en anaerob kontaktprocess, behandlas avloppsvattnen och andra organiska restprodukter från mejeriet tillsammans med vassle från både Umeå och Burträsk mejeri. Fettet i substratet avskiljs och behandlas separat. Den biogas som produceras vid nedbrytningen av det organiska materialet bränns i en brännare och ånga produceras. Syftet med den här studien är att utvärdera anläggningens design, valda processförhållanden och förfarandet under uppstarten av biogasanläggningen. Dessutom utvärderas interaktionen med den tyska entreprenör som är ansvarig för konstruktion och uppstart. Anläggningens utformning och valda processbetingelser är passande och de uppsatta målen är rimliga. Däremot är valet av ymp olämpligt och tidsplanen för uppstarten är för optimistisk. När denna studie avslutades var anläggningen i bruk och biogas producerades. Alla de mål för som formulerats hade dock inte uppnåtts. Ympens dåliga kvalitet är den mest bidragande orsaken till att uppstartsperioden har blivit förlängd. Arbetet under uppstarten och samarbetet med entreprenören har generellt sett varit lyckat. Man har dock stött på många komplikationer, varav de flesta har varit av typisk uppstartsnatur. Andra har varit resultatet av bristande planering och kommunikation. En rad konstruktions- och designfel har också identifierats under uppstarten. Slamflykt från reaktorerna har varit det mest betydande problemet hos den biologiska processen. Denna förlust av slam förmodas bero på olämpligt val av ymp och en alltför hastig ökning av den organiska belastningen i reaktorerna under uppstarten.

Technologies for pretreatment of waste activated sludges (WAS) prior to digestion are of increasing interest to wastewater treatment utilities because of their promise for improving sludge digestibility and reducing the mass of biosolids remaining after digestion. While there has been considerable study of pretreatment processes, a common approach to describing the impact of pretreatments on sludge biodegradability has not been developed. The overall objective of this study was to develop protocols that can be employed to characterize the impact of pretreatment processes on WAS digestion. Sonication and ozonation were employed as models of physical and chemical pretreatment technologies respectively. A range of physical, chemical and biological responses were evaluated to assess the impact of pretreatment on WAS properties as well as digestibility. WAS samples that were generated over a range of solids residence times (SRTs) under controlled operating conditions were employed to facilitate an assessment of the interaction between pretreatment and WAS properties on digestibility. The VS, COD and soluble TKN responses indicated that a significant fraction of the WAS solids were solublized by sonication and ozonation, however, it appeared that the types of materials which were solublized was affected by the SRT at which the WAS was generated and the level of pretreatment. The results indicated that the impact of pretreatment on biodegradability of WAS was not described by solublization values exclusively without considering the SRT of the sludge and the level and type of pretreatment. A higher level of proteinaceous materials was preferentially solublized as the result of pretreatment. Respirometry revealed that both sonication and ozonation substantially reduced the viable heterotrophs in the sludge and modestly increased the readily biodegradable fraction of COD. The ultimate yields of CH4 and NH4 in BMP tests and VFAs in BAP tests revealed that pretreatment marginally increased the ultimate digestibility of the sludges. Only a high dose of ozonation substantially increased the digestibility of the 15 day SRT sludge. However, both sonication and ozonation substantially increased the rate of hydrolysis which is typically the rate limiting process in WAS digestion. The BMP test was not a useful test to evaluate the rate of methane generation due to inhibition of methanogens in the early days of BMP test for pretreated sludges. The comparison between VFA and ammonia responses in day 10 of BAP test and ultimate values of these responses after 60 days in BMP test revealed linear relationships between these responses. According to these relationships, a set of models were introduced in this study. The models can be employed to predict the ultimate methane and ammonia generation using soluble COD, VFA or ammonia responses in day 10 of BAP tests. The BAP test was determined to be a shorter test (10 days) than the BMP (55 to 60 days) test and could provide information on the rates of hydrolysis and acidification/ammonification processes. Characterization of biodegradable and non-biodegradable material in WAS samples was conducted using a simplified ADM1 model. The characterization also revealed that proteins are a substantial fraction of biodegradable materials. The estimated ammonia, VFA and methane values from the stoichiometric model were similar to the corresponding values from the experiments. This supported the validity of the simplified model for all sludges employed in this study.

Anaerobic digestion is a common process for treatment of wastewater sludge from municipal sewage systems. Volatile sulfur compounds, including volatile organic sulfur compounds (VOSCs) and hydrogen sulfide, have been reported as the most odorous compounds in digestion emissions and impurities which can damage facilities for generation, transportation, storage, and utilization of biogas. There has been no comprehensive study on biological generation and degradation kinetics of VOSC or modeling VOSC behaviors through anaerobic sludge digestion. The goal of the present study was to establish a model for VOSC conversions in anaerobic sludge digestion which could facilitate quantitative analysis of VOSC emissions in anaerobic digestion. VOSCs and methionine were employed in dosed batch tests. VOSC conversion processes in anaerobic methionine digestion have been identified. The kinetics for the identified VOSC degradation and conversion processes were determined at 35 and 55 °C respectively. Mixed-second order kinetics were found to best fit the conversion processes. A model was established based on the identified processes and estimated kinetic constants. To extend the model to VOSC release in anaerobic sludge digestion, mesophilic and thermophilic incubations were conducted with four different sludge samples. The effects of temperature and sludge source on VOSC release patterns were assessed. It was found that an unidentified DMS generation mechanism was triggered in the mesophilic incubation of activated sludge in which iron was dosed. To apply the model which was established based on methionine degradation in sludge digestion, hydrolysis of particulate materials was incorporated. The model simulations for VOSC behavior in thermophilic batch incubation were able to represent the observed VOSC releases. However, the simulations could not well fit the observed VOSC release at 35 ° because the model did not include the unidentified DMS generation mechanism. Application of the model to bench-scale digesters was lack-of-fit. It may have been due to imprecise estimation of the degradable sulfur in the feed sludge. In addition, in the batch tests and digester operation the ratios of the raw and digested sludge were different. This might have resulted in different concentrations of the microorganisms which mediated biotransformations and hence resulted in different kinetic constants.

<p>Stockholm Water is a water and sewage company with Henriksdal as one of two wastewater treatment plants (WWTPs). At Henriksdal wastewater sludge generated in the wastewater treatment process is digested which generate biogas; a mixture of mainly methane and carbon dioxide. If purified to methane content of 96 - 98 % this gas is called biomethane.</p><p>Biogasmax is a project aiming to reduce the use of fossile fuels in Europe by providing that biogas is a good technical, economical and environmental alternative as vehicle fuel. The specific aim for Stockholm Water is to increase the biogas production at the existing plant in Henriksdal. Enzymatic treatment of wastewater sludge is an innovative technique earlier proofed to increase the biogas production from wastewater sludge with up to 60 %. The enzyme activity is in turn proven to significantly increase in the presence of a cation binding agent.</p><p>One aim with this thesis was to investigate if the sludge from Henriksdal wastewater treatment process at all is affected of enzymatic treatment in presence of a cation binding agent since this has shown to have some significance. The chemical oxygen demand (COD) was measured in the liquid phase of sludge after treatment and used as a measurement of treatment effect. Another aim of this thesis was to look into the possibility to increase the methane production from sludge at Henriksdal WWTP. This was investigated through batch laboratory digestion tests.</p><p>The sludge from Henriksdal WWTP was shown to be a good substrate for the enzymes added. COD in the liquid phase was increased with 17 – 32 % depending on the dose of enzymes and sodium citrate added. Digestion of sludge with a total addition of 18.6 mg enzymes per 1 g total solids (TS) and a concentration of 5 mM sodium citrate increased the methane production with almost 18 % compared to untreated sludge. This equals an increase of 18.3 % when converted to represent a totally blended and continuous digestion chamber at Henriksdal WWTP. The increased methane production also results in a sludge reduction out from the digestion chambers. The increased methane production and sludge reduction though does not fulfil the increased costs for the enzymes and sodium citrate applied. These doses must be decreased and the costs for both enzymes and sodium citrate must be reduced for this technique to be economically feasible in a full scale operation.</p>

Anaerobic digestion is a common process for treatment of wastewater sludge from municipal sewage systems. Volatile sulfur compounds, including volatile organic sulfur compounds (VOSCs) and hydrogen sulfide, have been reported as the most odorous compounds in digestion emissions and impurities which can damage facilities for generation, transportation, storage, and utilization of biogas. There has been no comprehensive study on biological generation and degradation kinetics of VOSC or modeling VOSC behaviors through anaerobic sludge digestion. The goal of the present study was to establish a model for VOSC conversions in anaerobic sludge digestion which could facilitate quantitative analysis of VOSC emissions in anaerobic digestion. VOSCs and methionine were employed in dosed batch tests. VOSC conversion processes in anaerobic methionine digestion have been identified. The kinetics for the identified VOSC degradation and conversion processes were determined at 35 and 55 °C respectively. Mixed-second order kinetics were found to best fit the conversion processes. A model was established based on the identified processes and estimated kinetic constants. To extend the model to VOSC release in anaerobic sludge digestion, mesophilic and thermophilic incubations were conducted with four different sludge samples. The effects of temperature and sludge source on VOSC release patterns were assessed. It was found that an unidentified DMS generation mechanism was triggered in the mesophilic incubation of activated sludge in which iron was dosed. To apply the model which was established based on methionine degradation in sludge digestion, hydrolysis of particulate materials was incorporated. The model simulations for VOSC behavior in thermophilic batch incubation were able to represent the observed VOSC releases. However, the simulations could not well fit the observed VOSC release at 35 ° because the model did not include the unidentified DMS generation mechanism. Application of the model to bench-scale digesters was lack-of-fit. It may have been due to imprecise estimation of the degradable sulfur in the feed sludge. In addition, in the batch tests and digester operation the ratios of the raw and digested sludge were different. This might have resulted in different concentrations of the microorganisms which mediated biotransformations and hence resulted in different kinetic constants.

Title: Food waste from grocery stores in Umeå- the potential for taking care of and reducing the amount of food waste. Author: Helene Myhrberg Abstract Food waste from grocery stores is an increasing problem in Sweden, and amounts to roughly 67 000 ton per year. This has consequences both for sustainability in general, but also for achieving the targets stipulated by the EU. Given this, it should be relevant for the society that grocery stores both decrease the amount of food waste but also develop better ways of dealing with food waste. Although there exist methods for this, the practicability of such measures are unknown. In this thesis I assess these issues by conducting interviews with owners and employees at five grocery stores in Umeå, asking them how they think about these questions. In particular, I focus on how to take care of and prepare food waste for anaerobic digestion and how to decrease volumes of food waste. In essence, I find that both the knowledge of, and interest in, these issues vary substantially between grocery stores. Further, for these measures to be feasible, it requires the process to be both economically efficient while not requiring too much time of work. With this in mind, it seems necessary to have a facility that can take care of both packed and unpackaged food waste, making it as cheap and simple as possible for the grocery stores. For reducing volumes of waste, most grocery stores agrees on better planning as the way to go. Key words: food waste, grocery stores, anaerobic digestion, decreasing of food waste.

The biogas plant Kungsängens gård, owned by Uppsala Vatten och Avfall AB, produces biogas and biomanure from organic household waste, food processing waste and slaughterhouse waste. In year 2012, 4.4 million Nm3 of biogas were produced from 25 200 tons of waste. Before digestion all substrate is sanitized by pasteurization at 70°C in order to kill pathogens. Another method, integrated thermophilic sanitation (ITS), is of interest in order to decrease the energy demand. The method implies that the substrate is sanitized during ten hours in the digestion chamber, where the temperature is 52°C. The purpose of this thesis was to compare pasteurization with integrated thermophilic sanitation from an energy point of view. The pasteurization´s impact on biogas production and energy yield was examined through experiments with two laboratory digesters, of which one was fed with pasteurized substrate and the other with non-pasteurized substrate. For the present pasteurization system, electricity and heat demand was surveyed. For the integrated thermophilic sanitation, a process design was developed and dimensioned and the electricity and heat demand was calculated. Thereafter, the energy yield and energy demand for the two sanitation systems were compared. The result showed that pasteurization had no effect on biogas production. The energy yield was on average 4.79 kWh/kg VS from non-pasteurized substrate and 4.74 kWh/kg VS from pasteurized substrate. There was no statistically significant difference between the reactors. The energy audit showed that pasteurization required 0.48 kWh/kg VS, which is 85 % of the total energy consumption at the facility. The digester warming demanded 0.077 kWh/kg VS for RK1 and 0.031 kWh/kg VS for RK2. The electricity consumption was 0.041 kWh/kg VS. The process of ITS was designed with a heat exchange from bio manure to substrate, followed by heating to 52°C by steam addition. The heat requirement was 0.24 kWh/kg VS and the electricity demand was 0.034 kWh/kg VS. The warming of the digesters was the same as in the present pasteurization system. The comparison between the existing pasteurization and the ITS showed that switching systems would save 0.243 kWh/kg VS or 46 % of the present energy consumption. This corresponds to annual savings of 1.22 GWh. A sensitivity analysis showed that the results were sensitive to assumptions regarding the heat exchanger in the case of ITS. 10 % energy losses resulted in smaller savings, 34 % or 0.91 GWh per year. There are increased risks of process disruptions if ITS is combined with an increased organic loading rate. 4.2 % reduction of the total biogas production erases the energy savings which means that it is important that process stability is ensured.

Anaerobic digestion (AD) of corn thin stillage (CTS) offers the potential to reduce corn grain ethanol production energy consumption. This thesis focuses on results collected from AD of CTS at mesophilic temperatures in batch and by down-flow fixed film reactor. Experiments conducted include a series of biochemical methane potential (BMP) assays that investigated the digestion of CTS as the sole carbon source at a variety of food-to- microorganism ratios with and without acclimated biomass, under co-digestion conditions and also with the addition of supplemental nutrients. Additional BMP assays were conducted which investigated the potential to reduce fresh water consumption by using of digested effluent for substrate dilution. Continuous studies employed two 28L down-flow stationary fixed film reactors to examine. Chemical oxygen demand and volatile solids removal efficiencies greater than 85% were achieved up to an organic loading rate of 7.4 g TCOD/L/d and hydraulic retention time of 5 days.

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No. of bitstreams: 1 silva_jep_me_bot.pdf: 2003164 bytes, checksum: d776b0516852a32e5763381a780cbe16 (MD5) Previous issue date: 2016-03-24 / Tendo em vista os problemas ambientais relativos as contaminações do solo e da agua oriundas dos dejetos produzidos em propriedades rurais, objetivou-se avaliar economicamente um biodigestor de fluxo contínuo, instalado na Escola Técnica Estadual “Orlando Quagliato”, situada no município de Santa Cruz do Rio Pardo-SP, bem como o processo de biodigestão anaeróbia e consequente produção de biofertilizante e biogás, oriundos dos dejetos de suínos e humanos. Os dejetos foram provenientes da suinocultura, que conta com 15 matrizes totalizando 148 animais, e dejetos humanos referente aos blocos de alojamentos para 200 alunos residentes, os quais diariamente são enviados para o biodigestor. O biodigestor em questão foi instalado com intuito de diminuir a contaminação do meio ambiente, produzir biogás e biofertilizante para utilização nos projetos produtivos da própria instituição escolar. Foram realizadas análises físico-químicas e microbiológicas do biofertilizante com a finalidade de avaliar a sua qualidade, no que tange a composição química e presença de microorganismos patogênicos para definição de sua utilização na agricultura. Considerando a produção de dejetos, realizou-se estimativa da produção de biogás, objetivando o potencial das receitas do processo. Foram analisados os custos de implantação, manutenção e depreciação. Os benefícios anuais foram dados pelo valor econômico dos nutrientes presentes no biofertilizante e pela produção de biogás estimada. Também foram estimados indicadores de viabilidade econômica, como Valor Presente Líquido (VPL), Taxa Interna de Retorno (TIR), PayBack (PB) e Ponto de Equilíbrio, utilizando uma taxa de desconto de 10,38% a.a. O investimento inicial para implantação atualizado foi de R$ 184.601,84 e os custos anuais do sistema foram de R$ 1.218,12 com manutenção e R$ 18.460,00 com depreciação. O benefício obtido com o emprego do biofertilizante foi de R$ 6.267,05.ano-1 e com produção de biogás equivalente estimada em R$ 24.594,86.ano-1, totalizando uma receita de R$ 30.861,91, expondo benefícios superiores aos custos anuais. Ficou evidenciado que tanto o biogás quanto o biofertilizante não são aproveitados plenamente, demonstrando ainda que o projeto foi superdimensionado na sua implantação considerando o plantel de suínos existentes, embora existam perspectivas para aumento do setor suinícola. / In view of the environmental problems of soil contamination to and from the water coming from the waste produced in farms aimed to economically evaluate a continuous flow digester, installed in the State Technical School "Orlando Quagliato", located in the municipality of Santa Cruz do Rio Pardo-SP, as well as the process of anaerobic digestion and consequent production of bio-fertilizer and biogas, derived from pig manure and human. The waste came from pig farming, which has 15 arrays totaling 148 animals, and human waste relating to the accommodation blocks for 200 resident students, who every day are sent to the digester. The biodigester in question was installed in order to reduce contamination of the environment, produce biogas and biofertilizers for use in productive projects of their own educational institution. physico-chemical and microbiological analyzes of biofertilizers were conducted in order to assess their quality, with respect to chemical composition and the presence of pathogenic microorganisms to define its use in agriculture. Considering the production of waste, there was estimated biogas production, aiming the potential revenue in the process. deployment costs, maintenance and depreciation were analyzed. The annual benefits were given the economic value of the nutrients present in biofertilizers and the estimated biogas production. Were also estimated economic viability indicators, such as net present value (NPV), internal rate of return (IRR), Payback (PB) and Balance, using a discount rate of 10.38% p.a. The initial investment was estimated at R$ 184,601.84 and the system annual costs were R$ 1.218,12 with maintenance and R$ 18.460,00 with depreciation. The benefit obtained by biofertilizer use was R$ 6.267,05.ano-1 and biogas production equivalent around R$ 24.594,86.ano-1, totaling a revenue of R$ 30.861,91, exhibiting superior benefits annual costs. This study revealed that as much biogas as biofertilizers are not used fully, further demonstrating that the project was oversized in its implementation, considering the amount of existing animals, although there are prospects for increased this sector.

Global warming along with energy demand and rising prices of natural energy resources have motivated studies to find some renewable and clean energy. The use of algae as third generation biofuel can avoid the competition for farmland and algae can be considered as a potential future source of renewable energy. Algae can be used for biogas production through anaerobic digestion (AD). Fucus vesiculosus and Fucus serratus are the two dominating species of brown seaweed growing in the Baltic sea in the southwest of Sweden. Pretreatment can significantly affect the biogas production since hydrolysis of algae cell wall structure is a rate-limiting step in AD process. In this study, four different pretreatments: mechanical, microwave (600W, 2min), ultrasonic (110V, 15min), and microwave combined with ultrasonic (600W, 2min;110V, 15min) were applied to the seaweed and then co-digested with biogas plant leachate. The aim was to investigate the biogas production and methane yield from AD after these pretreatments. The results showed when comparing with mechanical pretreated only, that the ultrasonic, ultrasonic combined with microwave and microwave pretreatments could obtain increased cumulative methane yields with 167%, 185% and 156% , respectively. The maximum methane yield was 260 ml/g∙VS with combined pretreatment after 20 days of digestion. The ultrasonic combined with microwave pretreatment showed a significant improvement of methane yield when comparing with mechanical pretreatment.