The concept of Sustainable Development is an interdisciplinary science. Transcending various academic fields the concept shows paths how the needs of present and future generations can be met through economic development on a finite natural resource base. Global warming and rising sea levels are just two of a series of phenomena that are directly attributable to human-induced increasing greenhouse gas levels in the atmosphere as consequence of the combustion of fossil fuels. Therefore, reducing greenhouse gas emissions through the use of renewable resources such as bioenergy are of vital importance if detrimental environmental effects are to be mitigated. The production of biogas in a decentralized context is receiving much attention in Germany as a means to reduce greenhouse gases and to counteract correlated negative environmental effects, respectively. In addition, socio-economic benefits such as local employment creation have the potential to empower rural communities. Subsidised by the German Renewable Sources Act and its various remuneration schemes, two 500kWel CHP biogas plants are producing through anaerobic digestion of maize silage and manure electricity and heat in the East German village Bollewick, which is the case study. The sustainability of this decentralized system is analyzed by applying a set of indicators. Socio-economic benefits for the population, economic efficiency of the digestion process and impacts of substrate costs on the profitability, greenhouse gas emissions due to land use change and biodiversity loss being some of these indicators. The thesis concludes that none of the sustainability indicators are sufficiently fulfilled in Bollewick. Especially the cultivation of the energy crop maize has despite crop rotations immense negative environmental effects. Therefore, the decentralized biogas production in the rurally coined village Bollewick is not sustainable.

The purpose of this study was to compare power output and ventilatory measurements between the steep ramp test (SR) and both the 30-second Wingate anaerobic (WAT) and standard cardiopulmonary exercise tests (CPET) in chronic obstructive pulmonary disease (COPD). 11 patients (7 males and 4 females) underwent spirometry, a CPET, WAT and SR test. Repeated measures ANOVA was used to compare the differences between the peak work rate of the CPET (CPET_peak), SR (SR_peak), and the average power of the WAT (W_avg). The W_avg was higher than the SR_peak, which was higher than the CPET (231.2 ± 113.4, 156.8 ± 67.9, 65.9 ± 35.9, p>0.05 respectively). There were no differences found between the tests at end-exercise for inspiratory reserve volume (IRV), ventilation (V_E), and end-expiratory lung volume (EELV). Tidal volume (V_T) was also compared between the tests as a percentage of the inspiratory capacity (IC) remaining at end-exercise and no differences were found. The similarity between the ventilatory measures indicates a similar level of constraint, despite the large difference in work rates achieved, in all 3 tests. This shows that a standard CPET underestimates leg power in COPD patients, and the WAT and SR may be better indicators of leg muscle power and anaerobic type exercise.

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.

The rapid accumulation of municipal solid waste is a significant environmental concern in our rapidly growing world. Due to its low cost, high energy recovery and limited environmental impact anaerobic digestion (AD) is a promising solution for stabilizing the organic fraction of municipal solid waste (OFMSW). Hydrolysis is often the rate-limiting step during AD of wastes with high solid content; this step can be accelerated by pretreatment of waste prior to AD. This thesis presents the results of alkaline pretreatment of OFMSW using NaOH and KOH. Four different pH levels 10, 11, 12 and 13 at two temperatures 23±1°C and 80±1°C were examined to study the effects of the pretreatment on (i) enhancing the solubility of the organic fraction of the waste, and (ii) enhancing the AD process and the biogas production. The effects on solubility were investigated by measuring changes in the soluble COD (SCOD) concentrations of pretreated wastes and the enhanced AD was investigated by measuring volatile solids (VS) destruction, total COD (TCOD) and SCOD removal in addition to biogas and methane production using biochemical methane potential (BMP) assay and semi-continuous laboratory reactor experiments. Pretreatment at pH 13 at 80±1°C demonstrated the maximum solubility for both NaOH and KOH pretreated samples; however the BMP analysis demonstrated that pretreatment at pH 12 at 23±1°C showed the greatest biogas yield relative to the removed VS for both chemicals. Thus pretreatment at pH 12 at 23±1°C using NaOH and KOH were examined using semi-continuous reactors at three different HRTs: 10, 15 and 20 days. Pretreatment demonstrated a significant improvement in the AD performance at SRTs of 10 and 15 days.

El objetivo principal es conocer la conducta del lactato en sangre.Situación bibliográfica.Estructurada en cinco apartados: reservas energéticas y límites metabólicos, la regulación ácido-base, el metabolismo del lactato, el umbral anaeróbico y las diferencias existentes entre niños y adultos. Nos centramos en los menores niveles de lacticemia en los niños, el mayor umbral anaeróbico en prepúberes frente a adultos y las diferencias de adaptación del metabolismo glucolítico.Material y métodos. Los criterios de selección de la población estudiada fueron: varones de 8-12 años, nivel socioeconómico medio, raza blanca, ausencia de limitaciones patológicas, volumen testicular menor o igual a 3 ml y la práctica del fútbol como actividad extraescolar. Utilizamos dos paquetes estadísticos: El BMDP y el SPSS 10.0. Realizamos una cineantropometría individual. Usamos para conocer la maduración ósea un método cuantitativo basado en el descrito por Tanner y Whitehouse. Hicimos dos pruebas en días diferentes. La primera prueba consistió en una cicloergometría triangular máxima. El umbral anaeróbico lo hallamos mediante la técnica V-Slope. Para la segunda prueba, cicloergometría rectangular submáxima, se escogió la carga correspondiente al umbral. Las extracciones capilares se obtuvieron sin detener la prueba. Realizamos una aproximación polinómica de la función lactato respecto al tiempo, a partir de los valores obtenidos.Resultados y conclusiones.Nuestros valores son similares a los obtenidos por Mocellin, Gildein y Billat, pero superiores a los de Williams. Considerando a nuestra muestra más estable, las cifras serían más acordes con las de Billat. Desafortunadamente, las diferencias en los procedimientos utilizados para definir el estadio estable, excluyen la comparación entre los diferentes estudios.1. En los sujetos estudiados, no se aprecia obesidad atendiendo al IMC y al cociente del perímetro cintura/cadera de la población seleccionada. El somatotipo medio obtenido es 3,7-5-2,7, es decir, endo-mesomorfo.2. La media del pico del consumo de oxígeno se ha establecido en 48,79 ml/Kg/min, siendo el valor en el umbral de 37,18 ml/Kg/min que equivale a un 76% del pico máximo.3. En el estudio multifactorial realizado, el 72,5% de toda la variabilidad es explicada por 5 grupos de factores, en el orden anotado a continuación: - Factor 1: Bicarbonato y presión parcial de dióxido de carbono.- Factor 2: Potencia.- Factor 3: Hemoglobina.- Factor 4: Lactatos, pH y bicarbonato.- Factor 5: Consumo de oxígeno, masa grasa, masa ósea y masa muscular.4. En la matriz de correlación del factor 4, los lactatos presentan correlaciones significativas con distintas variables entre las que destacamos la presencia del volumen testicular derecho. Esto implicaría una relación entre la madurez sexual y la concentración de lactatos.5. La variabilidad del pH, a los 2 minutos de realizar la prueba, en un 85,56% está en función de los factores lactato y bicarbonato.6. En la zona del umbral, transición aerobia-anaerobia, obtenida por nosotros, podemos hablar de unas cifras de lactato en las que se produce un cambio en el comportamiento de éste, previo a un estadio estable. Hablamos de unos valores de 3,57 ± 1,33 mmol·l-1.7. En la población en la que el comportamiento del lactato se estabiliza, con variación inferior a 1 mmol·l-1, el máximo estadio estable corresponde a unas cifras de 4,31 ± 1,08 mmol·l-1. En la subpoblación en la que el comportamiento del lactato se estabiliza, con variación inferior a 0,5 mmol·l-1, el máximo estadio estable corresponde a unas cifras de 3,78 ± 1,06 mmol·l-1. En esta subpoblación, el cambio en la conducta del lactato corresponde a la cifra de 3,63 ± 1,33 mmol·l-1. Estos valores, en esta subpoblación, nos indican una proximidad entre la modificación de un comportamiento ascendente del lactato y su posterior estabilización. / It is generally accepted that children's response to exercise is different from that of adults: children have distinctly lower maximal anaerobic power than do adolescents and adults, the muscle metabolic profile is better equipped for oxidative than glycolytic energy generation and the blood lactate concentrations are lower in children than in adults.The purpose of this study was to know the responses of blood lactate in prepubescent boys.Thirty-two soccer players (mean age 10.6 years) were tested during two days with two weeks in between testing sessions.Before the exercise test a complete physical examination was performed. They had no overt manifestations of any disease. Anthropometric measurements, x-ray of the left hand and wrist and gonadal maturation (orchidometry) were determined.On the first test, each subject performed an incremental triangular exercise (until exhaustion) using a bicycle ergometer. Gas exchange was measured breath by breath. The anaerobic threshold (AT) obtained is called ventilatory threshold 2 of Skiner and McLellan.On the second experimental day, the protocol for the test consisted of loaded cycling 50 watts under the AT during 5 min and after loaded watts of AT. Blood samples were collected after 5 min and every 3 min during the rest of the test, without the boys stopped. On cessation of exercise, blood samples were collected after 2 and 5 min. Free-flowing capillary blood samples for lactate determination were collected from a prewarmed fingertip.For statiscal analysis the packages SPSS 10.0 and BMPD were used. The somatotype turned out to be 3.7-5-2.7. The mean VO2peak was 48,79 ml/Kg/min, and the VO2 at AT was 37,18 ml/Kg/min corresponding to 76% of VO2peak. When the maximal steady state blood lactate (MLSS) concentration was assumed with increase, during all submaximal exercise, lower than 1 mmol·l-1 the values were 4,31 ± 1,08 mmol·l-1. If the MLSS was assumed with an increase lower than 0,5 mmol·l-1, the values were 3,78 ± 1,06 mmol·l-1. Our results were similar to those of Mocellin, Gildein and Billat, but higher than those of Williams. But direct comparisons between authors should only be made where identical procedures have been used.

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.

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. 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. 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. 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.

No description available.

Biogas is a source of renewable energy and is produced at anaerobic conditions. The gas consists mainly of methane (55-70 %) and carbon dioxide (30-45 %). Biogas can be used as vehicle fuel after the gas has been upgraded to a methane content of approximately 97 %. There are several companies in Sweden producing biogas. Svensk biogas AB in Linköping is one of the largest. The company has two biogas production plants; one in Linköping and one in Norrköping. To meet the surge demand for biogas it is not only important to increase the volumetric capacity of the digesters, but also to optimize the process at the existing production plants in different ways. Zeolites, a clay mineral, have earlier been shown to have a positive effect on anaerobic digestion of certain substrates. The aim of this master’s thesis was to investigate if the organic loading rate could be increased and/or if the hydraulic retention time could be reduced by addition of zeolites to a reactor treating slaughterhouse waste as a substrate. The aim was further to investigate which substance/substances that zeolites possibly could affect. Addition of the zeolite clinoptilolite in a continuously stirred lab tank reactor showed a significantly lower accumulation of volatile fatty acids compared to that in a control reactor without zeolites added, when the hydraulic retention time was kept low (30 days) and the organic loading rate was high (4.8 kg VS/ (m3 × day)). The same results were observed upon zeolite addition in a batch experiment, which also showed a decreased lag phase. Neither the specific gas production nor the methane concentration was significantly affected by addition of zeolites. Furthermore, addition of a possible inhibitor, long-chain fatty acids (LCFA), increased the lag phase further when slaughterhouse waste was used as a substrate. The conclusion from the observed results is that a metabolite or metabolites produced during the anaerobic degradation is/are the reason to inhibition and an increased lag phase.

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.