<p>Bioenergi är en stor industri i Sverige och står för en betydande del av energiomsättningen. Bioenergi i form av flis förvaras runt om i landet på hög i väntan på förbränning. Då högarna läggs upp startar olika processer som värmer upp stacken, ofta till temperaturer på 50°C under det första dygnet. En vanlig ansats i litteraturen är att denna temperaturstegring beror på aerob nedbrytning. Arbetet ämnar undersöka om denna uppvärmning endast beror av mikrobiella aktiviteter. Hypotesen prövas genom kalorimetriska mätningar av effekt från prover av flis och simulering av första dygnets temperaturutveckling i ett program som programmeras under arbetes gång.</p><p>I modellen så betraktas för enkelhets skulle flisstacken som en avlång figur med rektangulärt tvärsnitt. Figuren delas sedan in i lämpligt stora beräkningsceller. Problemet löses genom att iterativt räkna fram ett strömningsfält. Strömningsfältet och effekterna som räknas ut hålls sedan konstanta under ett tidssteg, 5-15min. Den magasinerade värmeenergin används sedan för att räkna fram en ny temperatur som så ger ett nytt strömningsfält och nya effekter. I modellen användes enbart explicita metoder eftersom de är snabbare och mycket enklare att programmera.</p><p>Ett flertal experiment i kalorimeter genomfördes med olika prover av flis och torv. Prover med barkflis gav högst utslag. Den högsta effekten som uppmättes var 2,16W/kg TS. Då effekter av denna storleksordning användes som inre effektgenerering i programmet gav detta inte en temperatur ökning motsvarande sådana som uppmätts i verkligheten. Detta tyder på att mer än aerob nedbrytning krävs för att ge en temperatur på över 50°C.</p> / <p>Bioenergy is a major industry in Sweden and accounts for a significant part of the energy production. Bioenergy in the form of wood chips is stored in piles across the country awaiting combustion. When the piles are acumulated, various processes that heat the stack begin, often to temperatures of 50 °C during the first day. A common approach in the literature is that this temperature rise is due to the aerobic decomposition. This paper will investigate whether the microbial activity is the fundamental cause for warming. The hypothesis is tested by calorimetric measurements of power from the samples of wood chips and simulation of the first day's temperature development in a programme that was desinated.</p><p>For simplicity the model considers an oblong wood chip pile with rectangular cross-section. The pile is then subdivided into appropriately sized calculation cells. The problem is solved by calculating a flow field iteratively. The flow field and the effects that are calculated is then static during one time step for approximately 5-15 minutes. The produced heat energy is then used to calculate a new temperature, which renders a new flow field and new powers. The model uses only explicit methods because they are faster and much easier to programme.</p><p>Several calorimetric experiments were carried out with various samples of wood chips and peat. Samples of bark chips achieved the highest result. The highest power measured was 2.16 W / kg DM. When the effects of this magnitude were used as internal power source in the programme the temperature did not increase corresponding to those measured in reality. This suggests that more than aerobic decomposition is needed to reach a temperature above 50°C.</p>

Silage bunker runoff is a form of agricultural pollution that contributes to aquatic ecosystem degradation. Current handling and treatment methods for this process wastewater are often ineffective or expensive. A woodchip bioreactor is an emerging treatment technology designed to facilitate denitrification through the provision of an anaerobic, carbon rich environment. A wood chip bioreactor treatment system, consisting of three pre-treatment tanks, two wood chip bioreactors, and one infiltration basin, was constructed at the Miller Research Complex in South Burlington, Vermont in 2016. Runoff and leachate from an adjacent silage storage bunker is directed into the system. The pre-treatment tanks include two settling tanks and one aeration tank. The former allows for sedimentation of organic matter, while the latter is designed to allow for nitrogen transformations that will help maximize nitrogen removal in the bioreactors. During the summer and fall of 2017, sampling occurred at four points within the system in order to determine the efficacy of various treatment steps. Samples were analyzed for nitrate (NOx—N), ammonium (NH4+-N), total nitrogen (TN), soluble reactive phosphorus (SRP), and total phosphorus (TP) in order to compare inflow and outflow pollutant concentrations and loads. Results indicate that this treatment system significantly reduced nutrient loads in the runoff. Over the entirety of the sampling period, the influent TN and TP mass load were both reduced by approximately 44%.

Bioenergi är en stor industri i Sverige och står för en betydande del av energiomsättningen. Bioenergi i form av flis förvaras runt om i landet på hög i väntan på förbränning. Då högarna läggs upp startar olika processer som värmer upp stacken, ofta till temperaturer på 50°C under det första dygnet. En vanlig ansats i litteraturen är att denna temperaturstegring beror på aerob nedbrytning. Arbetet ämnar undersöka om denna uppvärmning endast beror av mikrobiella aktiviteter. Hypotesen prövas genom kalorimetriska mätningar av effekt från prover av flis och simulering av första dygnets temperaturutveckling i ett program som programmeras under arbetes gång. I modellen så betraktas för enkelhets skulle flisstacken som en avlång figur med rektangulärt tvärsnitt. Figuren delas sedan in i lämpligt stora beräkningsceller. Problemet löses genom att iterativt räkna fram ett strömningsfält. Strömningsfältet och effekterna som räknas ut hålls sedan konstanta under ett tidssteg, 5-15min. Den magasinerade värmeenergin används sedan för att räkna fram en ny temperatur som så ger ett nytt strömningsfält och nya effekter. I modellen användes enbart explicita metoder eftersom de är snabbare och mycket enklare att programmera. Ett flertal experiment i kalorimeter genomfördes med olika prover av flis och torv. Prover med barkflis gav högst utslag. Den högsta effekten som uppmättes var 2,16W/kg TS. Då effekter av denna storleksordning användes som inre effektgenerering i programmet gav detta inte en temperatur ökning motsvarande sådana som uppmätts i verkligheten. Detta tyder på att mer än aerob nedbrytning krävs för att ge en temperatur på över 50°C. / Bioenergy is a major industry in Sweden and accounts for a significant part of the energy production. Bioenergy in the form of wood chips is stored in piles across the country awaiting combustion. When the piles are acumulated, various processes that heat the stack begin, often to temperatures of 50 °C during the first day. A common approach in the literature is that this temperature rise is due to the aerobic decomposition. This paper will investigate whether the microbial activity is the fundamental cause for warming. The hypothesis is tested by calorimetric measurements of power from the samples of wood chips and simulation of the first day's temperature development in a programme that was desinated. For simplicity the model considers an oblong wood chip pile with rectangular cross-section. The pile is then subdivided into appropriately sized calculation cells. The problem is solved by calculating a flow field iteratively. The flow field and the effects that are calculated is then static during one time step for approximately 5-15 minutes. The produced heat energy is then used to calculate a new temperature, which renders a new flow field and new powers. The model uses only explicit methods because they are faster and much easier to programme. Several calorimetric experiments were carried out with various samples of wood chips and peat. Samples of bark chips achieved the highest result. The highest power measured was 2.16 W / kg DM. When the effects of this magnitude were used as internal power source in the programme the temperature did not increase corresponding to those measured in reality. This suggests that more than aerobic decomposition is needed to reach a temperature above 50°C.

Storage of biomass is often associated with problems such as heat development, drymatter losses and reduction of fuel quality. The rise in temperature can potentiallycause a risk of self-ignition in the fuel storage. Moreover, emissions from storage pilescan cause health problems in the surrounding. The dry matter losses and reduction offuel quality can have economical effects. The aim of this thesis project is to developguidelines on how to store large amount of biomass at Vattenfalls heat and powerplants in an optimal way. Storage trials at Idbäckens CHP were done in order to studythe effect of storage on fuel quality, dry matter losses and temperature development.Two storage trials were performed over six weeks with waste wood chips and stemwood chips stored in about 4.5 m high outdoor piles. A trial over four days in whichwaste wood chips was placed on a heated surface was evaluated. A study to test thepossibility of using waste heat to dry waste wood chips was performed.Small but not negligible dry matter losses were observed in both of the piles of storedmaterial. The largest weekly losses were found during the first week of storage and adeclining behavior could thereafter be seen. The accumulated losses during six weeksof storage were 2.0 % and 1.7 % respectively, for waste wood and stem wood. Storageduring six weeks of waste wood and newly chipped stem wood did not cause anymajor deterioration of the fuel quality as such, beside the substance losses.No drying effect could be seen in the heated surface trial. The surface became warm,about 50°C, but it was not sufficient to dry the chips. The conclusion is that it is notpossible to dry large amount of chips on a heated surface with the design used hereand during four days.The overall conclusion is that in order to minimize the dry matter losses the materialshould be handled according to the LIFO (last in first out) principle. Wheneverpossible, try to purchase fuel that has been stored for a while since the more easilydegraded compounds has already been degraded through microbial activity. There is apossibility that the largest losses has already occurred. Furthermore, try also tocomminute the material (reduce the particle size) at the plant and as close in time tocombustion as possible.