För att nå de klimatpolitiska målen arbetar såväl Sverige som EU aktivt mot en cirkulär ekonomi där varje resurs nyttjas så effektivt som möjligt. En del i det arbetet handlar om att lyfta fram hållbara energikällor för att succesivt fasa ut fossila bränslen. Ett etablerat förnybart energislag, som fått mer uppmärksamhet på senare tid, är biogas. Produktionen av biogas sker via rötning av biologiskt material och kan generera el och värme, men även uppgraderas till fordonsgas. Ett av alla substrat som kan användas för rötning är gödsel. Den här studien har till syfte att undersöka omfattningen av den outnyttjade energipotentialen i gödsel från mjölkproducerande lantbruk i Sverige. Därtill ger den en bild av hur mycket koldioxid från fossila energikällor som skulle kunna minska i och med tillvaratagandet av energin i gödsel. En gårdsbaserad biogasanläggning vid Fredrikslunds lantbruk i Kalmar kommun är utgångspunkten och beräkningar görs tillsammans med data från bland annat Jordbruksverket och Energigas Sverige. För beräkning av möjligheten till minskat koldioxidutsläpp från fossil källa görs jämförelse med eldningsolja som används vid de svenska kraftverken. Resultatet visar att det finns en betydande energipotential i gödsel från svenska mjölk- producerande lantbruk där majoriteten av den ännu inte nyttjas för biogas- produktion. Nya styrmedel har tillkommit med syfte att gynna en ökad biogasproduktion, vilket kan öka chanserna för att ta vara på energipotentialen. Att genom ökad biogasproduktion minska mängden utsläpp av koldioxid till atmosfären från fossila källor ses också som möjlig. Sammanfattningsvis är studien ett exempel på hur en befintlig resurs kan effektiviseras ytterligare, ett arbete som troligen kommer bli än viktigare framöver. / To reach the climate goals, Sweden and the European Union are working towards a circular economy where the resources are used as efficiently as possible. Part of that work is about highlighting sustainable energy sources to gradually replace fossil fuels. An established, renewable type of energy, which has received more attention recently, is biogas. Biogas is produced through anaerobic digestion of biological material. The produced gas can generate electricity and heat, but it can also be upgraded to compressed biogas and used as automotive fuel. One of the substrates that can be used for digestion is manure. The aim of this study is to investigate the extent of the energy potential in manure from dairy farms in Sweden. In addition, it gives an idea of how much carbon dioxide from fossil energy sources that could be reduced if the energy potential in manure were used. Data is received from a farm- based biogas plant at Fredrikslund's farm in Kalmar as well as Swedish statistics of agriculture and energy. To estimate the possibility of reduced carbon dioxide emissions from fossil sources, a comparison is made with fuel oil. The results show that there is a considerable energy potential in manure from Swedish dairy farms where the majority is not yet used for biogas production. Reducing the amount of carbon dioxide emissions into the atmosphere from fossil sources through increased biogas production is also seen as possible.

The aim of this study was to assess the effect of composting process of cow manure and rice straw with application of cow urine and to evaluate the quality of composting products. There were two treatment piles, in which one pile was applied with cow urine every week and another pile without urine application. Each pile was set up by one tone cow manure and 500kg rice straw. The piles were half-covered by plastic foil to protect from rain and turned one a week. The composting duration lasted 8 weeks. The parameters such as temperature, pH, DM, density and nitrogen were monitored and observed during the 8-week period. The results showed that there was a significant difference in temperature, compost quality and duration between two piles with and without cow urine application. The application of cow urine increased significant nitrogen and phosphorous content and shortened the composting process. This study recommends that cow urine should be applied for composting process of cow manure and rice straw in order to increase the quality of compost. The final product was in the range of matured compost level and can be used directly for agriculture crop. / Mục tiêu của nghiên cứu nhằm đánh giá ảnh hưởng đến chất lượng phân compost của việc bổ sung nước tiểu vào trong quá trình ủ phân từ nguyên liệu phân bò và rơm rạ. Thí nghiệm được thực hiện trên hai đống ủ phân, một đống ủ được bổ sung nước tiểu bò hàng tuần và một đống ủ không bổ sung nước tiểu bò như là một nghiệm thức đối chứng. Mỗi đống ủ được trộn 1 tấn phân bò và 500kg rơm. Đống ủ phân được đậy kín một nửa phía trên nhằm ngăn cản ảnh hưởng của mưa và được đảo trộn một lần mỗi tuần. Quá trình thí nghiệm được tiến hành trong 8 tuần. Các chỉ tiêu như nhiệt độ, pH, DM, mật độ và chất dinh dưỡng Nitơ và Phốt Pho được quan trắc trong thời gian ủ. Kết quả cho thấy có sự khác biệt đáng kể giữa hai đống phân ủ đối với các chỉ tiêu như nhiệt độ, chất lượng phân compost và thời gian ủ. Đống ủ phân có bổ sung nước tiểu có hàm lượng Nitơ và Phốt pho cao hơn và thời gian ủ ngắn hơn. Kết quả nghiên cứu khuyến cáo nên bổ sung nước tiểu bò cho quá trình ủ phân compost nhằm tăng hàm lượng chất dinh dưỡng cho sản phẩm phân compost. Sản phẩm sau quá trình ủ đạt mức độ phân hữu cơ và có thể sử dụng cho cây trồng.

The characteristics of anaerobic batch co-digestion of water hyacinth (WH) with pig manure (PM) under seven mixing ratio 100%WH; 80%WH : 20%PM; 60%WH : 40%PM; 50%WH : 50%PM; 40%WH : 60%PM; 20%WH : 80%PM and 100%PM were investigated, each treatment was conducted in five replications with daily loading rate at 1 gVS.L-1.day-1. During the anaerobic digestion process of 60 days, maximum biogas production occurred in two periods, the first stage from 12- 22 days and second stage from 30 - 35 days. The maximum daily biogas productions from each stage were 17.2 L.day-1 and 15.1 L.day-1, respectively. The cumulative biogas production varied between 60 L (100%PM) and 360 L (60%WH : 40%PM). The results showed that the biogas yields of co-digestion 40- 80%WH were higher from 34.6 to 56.1% in comparison with 100%PM and from 109 to 143% in comparison with 100%WH. When mixing with WH, treatments were received more methane and the methane contents were higher than 45% (v/v) that good for energy using purposes. / Nghiên cứu được thực hiện nhằm khảo sát khả năng gia tăng lượng khí sinh học khi tiến hành đồng phân hủy yếm khí lục bình (WH) và phân heo (PM) ở các tỉ lệ phối trộn khác nhau gồm 100%WH; 80%WH : 20%PM; 60%WH : 40%PM; 50%WH : 50%PM; 40%WH : 60%PM; 20%WH : 80%PM và 100%PM. Các nghiệm thức được nạp lượng nguyên liệu là 1 gVS.L-1.ngày-1 và bố trí lặp lại 5 lần. Theo dõi quá trình phân hủy của các nghiệm thức trong 60 ngày ghi nhận có 2 khoảng thời gian lượng khí sản sinh nhiều nhất - giai đoạn 1 từ ngày 12 đến 22, giai đoạn 2 từ ngày 30 đến 35. Lượng khí sản sinh cao nhất tương ứng trong mỗi giai đoạn là 17.2 L.ngày-1 và 15.1 L.ngày-1. Lượng khí tích lũy trong suốt thời gian thí nghiệm ghi nhận thấp nhất ở nghiệm thức 100%PM đạt 60 L, và cao nhất ở nghiệm thức 60%WH : 40%PM đạt 360 L. Năng suất khí sinh ra của các nghiệm thức phối trộn lục bình từ 40 đến 80% cao hơn từ 34,6 đến 56,1% so với nghiệm thức 100%PM và cao hơn từ 109% đến 143% so với nghiệm thức 100%WH. Hàm lượng mê-tan sinh ra từ các nghiệm thức có phối trộn lục bình ổn định trong khoảng > 45% đảm bảo nhiệt lượng cho nhu cầu sử dụng năng lượng.

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Rising global antibiotic resistance has caused concerns over sources and pathways for the spread of contributing factors. Majority of the antimicrobials used in the U.S. are involved in veterinary medicine, primarily with livestock rearing. Animal manure land application integrates livestock farming and agroecosystems. This manure contains antibiotic resistant elements (AREs) (resistant bacteria, resistance genes, and veterinary antibiotics) that contribute towards antimicrobial resistance. Altering manure application techniques can reduce surface runoff of other contaminants such as excess N and P, pesticides, and hormones, that can impact water quality. Conventional tillage practices in the U.S. has reduced or stopped, making subsurface injection of manure a promising option when compared to surface application. Our research compared manure application methods, manure application seasons, cropping system, and manure-rainfall time gaps to gauge the impact on AREs in the environment. Two field-scale rainfall simulation studies were conducted along with one laboratory study. Using the injection method lowered concentrations of manure associated AREs entering surface runoff. When manure was surface applied and rainfall occurred 7 d after application, 9-30 times less resistant fecal coliform bacteria (FCB) entered surface runoff when compared to 1 d time gap for that broadcast method. Within a day of manure application, antibiotic resistance gene (ARG) profiles in soil began to differ from each other based on manure application and soil ARG richness in all manure-amended soil increased compared to the background. Runoff from injection plots contained 52 ARGs with higher abundance compared to runoff from surface applied plots. ARGs in the former were more correlated to soil and more correlated to manure in the latter. The highest antibiotic concentrations were in the injection slit soil of those plots. Antibiotic concentrations in samples corresponded positively to concentrations of resistant FCB and ARGs, and there was a positive correlation between resistant FCB and their associated ARGs (Spearman's ρ = 0.43-0.63). A CRIISPR-Cas12a assay for quantification of ARGs in environmental samples was just as precise as conventional methods. There is also potential for in-situ detection. These combined results can hopefully help farmers improve manure management practices that mitigate spread of AREs to surrounding water, crops, and soil. / Doctor of Philosophy / Rising global antibiotic resistance cause concerns over sources and pathways for the spread of contributing factors. Most of the antimicrobials used in the U.S. are involved in veterinary medicine, especially with livestock rearing. Overuse of antibiotics that are medically important to human medicine compromises the effectiveness of our medicines. Animal manure contains antibiotic resistant elements (AREs) such as resistant bacteria, resistance genes, and antibiotics) that contribute towards resistance issues. Once these AREs enter the environment, they can be taken up by crops, runoff into surface water or leached into ground water, or even reside within the animal products we consume. Altering manure application techniques is beneficial for nutrient conservation but also potentially for reducing ARE spread. With our research, we compared manure application methods, manure application seasons, cropping systems, and manure-rainfall time gaps to find ways to balance the need for manure application and the spread of resistance. We used two field-scale rainfall simulation studies along with one laboratory study. Overall, using the injection method resulted in significantly lower concentrations of manure associated AREs entering surface runoff. When manure was surface applied and rainfall occurred 7 d after application, less resistant fecal coliform bacteria (FCB) entered surface runoff when compared to the 1 d time gap for broadcast methods. Within a day of manure application, antibiotic resistance gene (ARG) profiles in soil began to differ from each other and soil ARG totals in all manure applied soil increased compared to the background. Runoff from injection plots contained more soil ARGs and runoff from surface applied plots containing more manure associated ARGs. The subsurface injection method also caused highest antibiotic concentrations in the injection slit soil of those plots. High antibiotic concentrations in samples generally meant high concentrations of resistant FCB and ARGs, and resistant FCB were also found with their associated ARGs as well. A CRISPR-Cas12a assay for quantification of ARGs in environmental samples was just as precise as conventional methods. There is also potential for onsite detection. These combined results can hopefully help farmers improve manure management practices that mitigate spread of AREs to surrounding water, crops, and soil.

Widespread use of antibiotics in livestock production can result in the dissemination of bacteria carrying antibiotic resistance genes (ARGs) to the broader environment. Within agroecosystems, ARGs can pose a risk to livestock handlers, farmers, and ultimately consumers. The overall goals of this dissertation are to examine the presence of resistance (antibiotic, metal) in agricultural soils and evaluate the most critical potential points of best management control of antibiotic resistance spread along the agricultural production chain. The relative impacts of agricultural practices, manure management, native soil microbiota, and type of crop grown and harvested on the agricultural resistome are multi-dimensional and cannot be captured via a single analytical technique or by focusing on one specific point in the agricultural process. Culture-, molecular "indicator"-, and next-generation sequencing- based methods were employed to characterize antibiotic resistance via taxonomic and functional profiles on the broader manure, soil, and vegetable surface microbial communities through 16S rRNA amplicon sequencing and shotgun metagenomics. Although antibiotic concentrations dissipated in the soil after 28 days after amendment application, antibiotic resistance presence was recoverable throughout the entire 120d growing season in the compost and manure amendments, the amended soil, and on vegetable surfaces. The addition of organic fertilizers increased antibiotic resistance presence compared to background levels. Further, metals and metal resistance were also measured in the amended soils and were found to be at greater levels in the inorganically fertilized soils compared to the manures and compost amended soils. Analysis of the widespread agroecosystem microbial community composition and broader metagenome has characterized varying genera profiles in the soil and on the vegetable surfaces and specific ARG and mobile genetic element (plasmid) co-occurrences. These co-occurrences highlight which ARGs may be most critical for future antibiotic resistance dissemination research. It is imperative to employ multiple methods when measuring agricultural resistance, as one method alone may miss significant patterns and lead to different best management recommendations. Linking the livestock manure, soil, and vegetable surface-associated ARBs, ARGs, resistomes, and microbiomes will help identify critical control points for mitigation of agricultural dissemination of antibiotic resistance to the environment and food production. / Doctor of Philosophy / By 2050, it is estimated that antibiotic resistant infections will be the leading cause of death worldwide. It is important to consider human, animal, and environmental health when researching antibiotic resistance, which is known as a "One Health" approach. In this dissertation work, I focus on the environmental side of antibiotic resistance in our agricultural systems. Agriculture is a known source of antibiotic resistance due to its use of antibiotics in livestock as a treatment for illness, and in some instances, as a growth promoter. Over one growing season, I measured antibiotic resistance in an agricultural setting using many techniques. First, I analyzed the effects of inorganic (chemical) versus organic (manure and compost) fertilization on antibiotic resistance in the soil. I measured antibiotic resistance by growing antibiotic resistant bacteria, quantifying specific antibiotic resistant genes (ARGs) using DNA amplification, and quantifying all the ARGs in the soil using a next-generation sequencing (NGS) technique called shotgun metagenomics. I found that adding manure to the soil increases ARGs compared to background soil levels, and that composting in an effective management strategy in decreasing ARGs in the soil over time. Second, I analyzed the same effects of fertilization on metal resistance in the soil. I was able to use the same NGS dataset to measure metal resistance genes (MRGs). I found that adding inorganic chemical fertilizer increases MRGs in the agricultural soils compared to the organic (manure or compost) fertilizer. Additionally, I studied the microbes that live in the agricultural soils using another kind of NGS data specific for microbial identification. I found that although there were small differences between the microbial populations in the soil when fertilizers were added, they returned to similar composition over the growing season. Lastly, I measured antibiotic resistance and microbes throughout the entire agricultural system. I picked the point of fertilization (manure management), soil, and the lettuce surface to evaluate if antibiotic resistance spreads from the farm to the vegetable that ends up on a consumer's plate. I found that at each point antibiotic resistance is present, but at different levels. Composting reduces ARGs compared to raw manure. Agricultural soils may act as a natural buffer to antibiotic resistance. Lettuce plants grown in compost fertilized soils have less ARGs than lettuce plants grown in manure. There are many agricultural management practices that effectively reduce antibiotic resistance and using all of them plus many measurement methods will ultimately help farmers and consumers reduce antibiotic resistance in our agricultural systems.

Pyrolytic oils produced from poultry litter differ in physico-chemical properties and the chemical composition. The litter is composed of manure and bedding material with traces of spilled feed and feathers. The type and amount of bedding material was varied to investigate its influence on the pyrolysis of layer manure. 400g of each feedstock: manure, wood (pine and oak), and mixtures of manure and wood in proportions (75:25 50:50, and 25:75 w/w %) respectively were subjected to fast pyrolysis at 450oC in a fluidized bed reactor. The total pyrolytic oil yield ranged from 43.3% to 64.5 wt%. The highest bio oil yield and the lowest char yield were obtained from oak wood. The manure oil had the highest HHV of 29.7 MJ/kg, the highest pH (5.89), the lowest density (1.14 g/cm3) and a relatively low viscosity of 130cSt. The oils had relatively high nitrogen content ranging from 5.88wt% to 1.36 wt%; low ash content (approximately <0.07wt %) and low sulfur content (<0.28wt %). FT-IR, 13CNMR, and 1HNMR analysis showed that manure oil was rich in aliphatic hydrocarbon and primary and secondary amides and the addition of wood introduced oxygenated compounds like aliphatic alcohols, phenols, aromatic ethers, and carbonyl/carboxylic groups into the oil. TG/DTG analysis also showed that the thermal decomposition of the oils were different depending on the amount and the type of wood in the manure/wood mixture. The parametric variables used for the mixture of 50% manure and 50% pine wood shavings study were; temperature (400-550°C), nitrogen gas flow rate (12-24 L/min), and feed rate (160-480 g/h). The results showed that the pyrolysis product yields, physical properties and the chemical composition of the oil were influenced by all parameters. Temperature was the most influential factor and its effect on the liquid, char and gas yields were significant. It was evident that depending on the gas flow rate and the feed rate, a maximum oil yield (51.1wt.%) can be achieved between 400-500 oC. Also an increase in temperature significantly increased the oil viscosity and decreased the carbonyl/carboxylic and the primary aliphatic alcohol functional groups in the oil. The study on the influence of wood on the stability of the oils when stored at ambient conditions for 8 months in a 30ml glass bottle showed that the viscosity of the oils increases when stored, however the manure oil was relatively more stable and the oil from the 50/50 mixture for both pine and oak was the least stable. It was found that the stability of the oils from the manure and wood mixtures were dependent on the amount and the type of wood (pine or oak) added to the manure. Also the addition of 10% solvent (methanol/ethanol) to the oil from 50% manure and 50% pine reduced the initial viscosity of the oil and was also beneficial in slowing down the increase in viscosity during storage. / Master of Science

Two experiments were conducted with caged layer waste. In the first experiment fresh waste was treated with: no additive, 2% formaldehyde, 3% sodium metabisulfite, 1% formaldehyde and 2% propionic acid, 3% formic and 2% propionic acids and stored in polyethylene lined 208 liter metal drums. In experiment II waste treated with 2% formaldehyde, 1 % formaldehyde and 2% prop ionic, 3 % formic and 2% propionic (w/w), stored for at least 42 d, used in a metabolism trial as N supplements to a basal diet fed to sheep. The formaldehyde, formaldehyde/propionic and formic/propionic treatments eliminated the bacterial decomposition of the waste and no undesirable fermentation was observed on the stored material. Waste treated with no additive or sodium metabisulfite underwent putrefaction. Nitrogen supplementation of a basal diet with treated caged layer wastes improved apparent digestibility of crude protein and N retention in sheep fed these diets. Supplementation of a basal diet with chemically treated caged layer waste improves the nutritional value of the diet which suggests that caged layer waste is efficiently utilized as a N source by ruminants when used as a protein supplement. / Master of Science