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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Comparison of Dairy Manure Anaerobic Digestion Performance in Gas-lift and Bubble Column Digesters

Tang, Jing 07 January 2010 (has links)
Anaerobic digestion is one of the most promising management options for dairy manure treatment. Manure wastewater from dairy farms has been used for methane production for decades. However, performance failure due to inadequate mixing is routine. In general, the mixng of anaerobic digester is achived throguh mechnical stirring, liquid circulation, and gas circulation, among which the gas circulation proves to be the most effcient way. In this work, we studied the liquid flow pattern of two differetn type of gas-circualtion based anaerobic digesters, with the aim to understand the effects of hydrodynamic behavior of the digesting liquid on the anaerobic digestion performance, so a better mixing strategy can be provided. We used two 20-L gas circulation based anaerobic digesters with confined (gas-lift) and unconfined (bubble column) design. The anaerobic digestion performance and mixing behaviors were studied at different gas recirculation rate. It was found that the biogas production from the bubble column was constantly higher than that from gas-lift digester. However, the overall flow of the two digesters, which is indicated by residence time distribution (RTD), showed a similar pattern. Furhter investigation of local liquid flow behavior using Computational Fluid Dynamic (CFD) indicate that the bubble column accumulated higher portion of sludge in the bottom of the digester, which has a higher TS and VS, COD, and biomethane production potential than those from the gas-lift digester. This is the reason that the biogas production from the bubble column is higher than the gas-lift digester. Through this study, a thorough characterization of the flow behavior of the anaerobic digester were developed, and provided a deep insight of its influence on the anaerobic digestion performance. / Master of Science
22

The Occurrence and Fate of Steroid Hormones from Manure Amended Agriculture Fields

Sosienski, Theresa Ann 14 July 2017 (has links)
Hormones are endocrine disrupting compounds, which have been shown to alter the sexual development of aquatic organisms. Animal manure applications to agricultural fields for nutrient management can be a source of environmental hormones. This dissertation investigates the occurrence of hormones in fields applied with various manures and their adjacent streams, as well as the effect of manure application technologies on the fate of hormones in soils, sediments, and runoff. A total of 11 hormone compounds were studied. All studied analytes were quantified using liquid chromatography and triple-quadrupole mass spectrometry following various sample extraction and clean-up strategies. The spatial and temporal distribution of manure-associated hormones in a manure surface applied agricultural field and adjacent stream was studied at time points up to 7.5 months after a routine manure application. Hormones were detected mainly in the top 0-5cm soils. Significantly higher levels of hormones were found in the drystack applied area of the field when compared to dairy manure slurry applied portion. New technologies for the subsurface application of poultry litter show promise as a tool to reduce the transportation of environmental hormones in surface runoff. Once adequate sampling protocols were established; it was determined that subsurface injection of both dairy manure and poultry litter reduced the impact of manure surface runoff. Hormones also showed little vertical and lateral movement in the soil. The transformation rates of 1,4-androstadiene-3,17-dione, 4-androstene-3,17-dione and estrone were studied comparing the effects of temperature, soil type, and application type. The calculated half-life of 1,4-androstadiene-3,17-dione in poultry litter surface-applied soils was 1.9 times higher than that in the poultry litter subsurface-injected soils, indicating a faster dissipation rate in the injection slits. Estrone persisted at detectable levels for the duration of the study in all treatments. The continued use of best management practices and innovative manure management techniques for the reduction of nutrients, sediment and other contaminants has the potential to also reduce hormone transport to the natural environment. Monitoring many different types of hormones in all areas of an environmental system will continue to provide better information on the occurrence and fate of hormones sourced from manure amended soils. / Ph. D.
23

Compartmental Process-based Model for Estimating Ammonia Emission from Stored Scraped Liquid Dairy Manure

Karunarathne, Sampath Ashoka 06 July 2017 (has links)
The biogeochemical processes responsible for production and emission of ammonia from stored liquid dairy manure are governed by environmental factors (e.g. manure temperature, moisture) and manure characteristics (e.g. total ammoniacal nitrogen concentration, pH). These environmental factors and manure characteristics vary spatially as a result of spatially heterogeneous physical, chemical, and biological properties of manure. Existing process-based models used for estimating ammonia emission consider stored manure as a homogeneous system and do not consider these spatial variations leading to inaccurate estimations. In this study, a one-dimensional compartmental biogeochemical model was developed to (i) estimate spatial variation of temperature and substrate concentration (ii) estimate spatial variations and rates of biogeochemical processes, and (iii) estimate production and emission of ammonia from stored scraped liquid dairy manure. A one-dimension compartmentalized modeling approach was used whereby manure storage is partitioned into several sections in vertical domain assuming that the conditions are spatially uniform within the horizontal domain. Spatial variation of temperature and substrate concentration were estimated using established principles of heat and mass transfer. Pertinent biogeochemical processes were assigned to each compartment to estimate the production and emission of ammonia. Model performance was conducted using experimental data obtained from National Air Emissions Monitoring Study conducted by the United States Environmental Protection Agency. A sensitivity analysis was performed and air temperature, manure pH, wind speed, and manure total ammoniacal nitrogen concentration were identified as the most sensitive model inputs. The model was used to estimate ammonia emission from a liquid dairy manure storage of a dairy farm located in Rockingham and Franklin counties in Virginia. Ammonia emission was estimated under different management and weather scenarios: two different manure storage periods from November to April and May to October using historical weather data of the two counties. Results suggest greater ammonia emissions and manure nitrogen loss for the manure storage period in warm season from May to October compared to the storage period in cold season from November to April. / Ph. D.
24

Tratamento da fração líquida de estrume bovino em reator anaeróbio híbrido em escala piloto / Treatment of liquid fraction of dairy manure in a pilot-scale anaerobic hybrid reactor

Dias, Pâmela Castilho 06 October 2017 (has links)
O presente trabalho teve como principal objetivo avaliar o desempenho de um reator anaeróbio híbrido (RAnH) em escala piloto no tratamento da fração líquida de estrume bovino, visando à remoção de matéria orgânica e à produção de biogás. O RAnH estudado apresentava volume total 6,2 m3 e foi composto por manta de lodo, na qual a biomassa encontrava-se suspensa, e leito fixo, no qual utilizou-se Biobob® como material suporte para imobilização da biomassa. Para dar suporte a partida do RAnH, a água residuária em estudo foi submetida a teste de biodegradabilidade visando avaliar a influencia da inoculação do reator no potencial de biodegradabilidade e de produção de metano. No teste, a inoculação mostrou-se adequada, apresentando biodegradabilidade de 57 ± 4% e produção de metano de 344 ± 26 mL CH4. g SV-1. A operação do RAnH foi realizada por 260 dias e foi dividida em duas etapas: etapa inicial, na qual se procedeu a adequação da operação do reator, e etapa experimental, na qual se avaliou o desempenho do reator perante o aumento progressivo da carga orgânica aplicada. Durante a operação do reator foi alcançada a aplicação de COV bruta total de 25,50 ± 2,53 kg DQO.m-3.d-1 e a COV solúvel total de 7,69 ± 0,02 kg DQO.m-3.d-1, sendo atingido o TDH de 1,27 ± 0,004 d. O RAnH apresentou eficiência de remoção média de 65 ± 4 % durante a etapa experimental. A produção média de metano foi de 0,310 ± 0,095 m3 CH4. m-3.d-1 e 0,098 ± 0,018 m3 CH4. kg SVad, com 89 ± 3% de metano na composição do biogás. O potencial de produção de energia elétrica estimada com base no reaproveitamento metano produzido no RAnH foi de 0,89 kWh.m-3. O aproveitamento desta energia em sistema com vazão de 3.500 m3.d-1 geraria energia suficiente para abastecer 615 residências e uma economia mensal de R$ 11.835,09. / The main objective of this work was to evaluate the performance of a pilot-scale anaerobic hybrid reactor (RAnH) in the treatment of the liquid fraction of dairy manure, in order to remove organic matter and produce biogas. The applied RAnH had a total volume of 6.2 m3 and was composed of sludge blanket, in which the biomass was suspended, and fixed bed, in which Biobob® was applied as a support material for biomass immobilization. In order to support RAnH startup, the wastewater under study was submitted to a biodegradability test to evaluate the influence of reactor inoculation on the biodegradability potential and methane production potential. In the test the inoculated condition presented appropriate biodegradability (57 ± 4%) and higher methane production potential (344 ± 26 mL CH4.gVS-1). The RAnH operation was performed for 260 days and was divided into two stages: initial stage, in which the reactor operation was adjusted, and the experimental stage, in which the reactor performance was evaluated with the progressive increase of the applied organic load. During the reactor operation was reachead total raw VOC application of 25.50 ± 2.53 kg COD m-3.d-1 and total soluble VOC of 7.69 ± 0.02 kg COD m-3.d-1, with the HRT of 1.27 ± 0.004 d. The RAnH presented average removal efficiency of 65 ± 4% during the experimental stage. The average methane production was 0.310 ± 0.095 m3 CH4.m-3.d-1 and 0.098 ± 0.018 m3 CH4. kg VSad, with 89 ± 3% of methane in the biogas composition. The potential of electric energy production estimated based on the reuse of the methane produced in the RAnH was 0,89 kWh.m-3. The use of this energy in a system with a flow of 3,500 m3.d-1 would generate sufficient energy to supply 615 homes and a monthly saving of R$ 11,835.09.
25

Formas orgânicas e inorgânicas de fósforo em solos tratados com resíduos orgânicos e relações com disponibilidade / Organic and inorganic phosphorus forms of soils ammended with organic wastes and relationships with availability

Braos, Lucas Boscov 01 December 2017 (has links)
Submitted by LUCAS BOSCOV BRAOS null (lucasbraos@hotmail.com) on 2018-01-05T13:13:58Z No. of bitstreams: 1 Tese_Lucas_Boscov_Braos.pdf: 1554570 bytes, checksum: e5419ca73de20bad4b5d5693b1cbae54 (MD5) / Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2018-01-08T10:18:47Z (GMT) No. of bitstreams: 1 braos_lb_dr_jabo.pdf: 1554570 bytes, checksum: e5419ca73de20bad4b5d5693b1cbae54 (MD5) / Made available in DSpace on 2018-01-08T10:18:47Z (GMT). No. of bitstreams: 1 braos_lb_dr_jabo.pdf: 1554570 bytes, checksum: e5419ca73de20bad4b5d5693b1cbae54 (MD5) Previous issue date: 2017-12-01 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Conhecer as formas e as transformações do fósforo (P) aplicado via fertilizantes orgânicos e minerais é importante para melhorar o manejo e otimizar o uso do P. Os objetivos com o presente trabalho foram avaliar formas orgânicas e inorgânicas de P em solos adubados com esterco bovino, torta de filtro e superfosfato triplo em função do tempo de contato solo-adubo, e estabelecer relações entre as formas de P e a disponibilidade. As formas de P orgânico (Po) e inorgânico (Pi) foram determinadas em amostras de Latossolo Vermelho argiloso (LV) e de Argissolo Vermelho Amarelo arenoso (PVA), adubadas ou não com 100 mg dm-3 de P nas formas de esterco bovino, torta de filtro e superfosfato triplo, e mantidas em incubação por 15, 45, 90 e 180 dias. O Pi foi fracionado em P solúvel e fracamente retido, P ligado ao Al ou Fe, P ocluso e P ligado ao Ca. O P orgânico foi fracionado em Po lábil, Po da biomassa microbiana, Po moderadamente lábil, Po dos ácidos fúlvicos, Po dos ácidos húmicos e Po residual. Com as amostras de solo também foi conduzido experimento com plantas de milho para determinar a produção de matéria seca e a absorção de P. No latossolo foi observado maior teor de Pi ocluso e Po residual e a adubação também aumentou os teores dessas frações, indicando que o P dos adubos é incorporado às frações menos disponíveis, o que torna os teores de P disponível menores neste solo. No argissolo predominaram Pi ligado ao Fe e Po associado aos ácidos húmicos, e o P adicionado foi incorporado às formas ligadas ao Al e ao Fe, que contribuíram para maior disponibilidade de P neste solo. As frações mais estáveis tanto do Pi quanto do Po não se correlacionaram com o P disponível, e as frações menos estáveis se correlacionaram com a matéria seca acumulada e o P absorvido pelas plantas, indicando que mesmo estando em maior teor, as frações mais estáveis contribuem de forma mais limitada para a absorção de P pelas plantas. No solo latossolo, o acúmulo de P nas formas ligadas ao Al e ao Fe, no tratamento com superfosfato triplo, foi determinante para maior disponibilidade. No solo argissolo, o aumento das formas de P ligado ao Al e ao Fe, junto ao menor acúmulo de P ocluído no tratamento com esterco bovino, resultou na maior disponibilidade. A interação entre tipo de solo e adubo definiu o destino do P aplicado, bem como a disponibilidade / Evaluating the forms and transformations of phosphorus (P) applied via organic and mineral fertilizers is important to improve the management and optimize the use of P. The objectives of the present study were to evaluate organic and inorganic forms of P in two soil types, fertilized with dairy manure, filter cake and triple superphosphate, as a function of the incubation time, and to establish relationships between soil P forms and P available, plant uptake P and growth. The organic (Po) and inorganic (P) forms of P were determined on samples of typic Hapludox clayey and arenic Hapludult sand, fertilized or not with 100 mg dm-3 of P as dairy manure, filter cake and triple superphosphate, and incubated for 15, 45, 90 and 180 days. Pi was fractionated into soluble and weakly bound P, Al or Fe bound P, occluded P and Ca bound P. The organic Po was fractionated into labile Po, microbial Po, moderately labile Po, fulvic acids associate Po, humic acids associate Po and residual Po. In the soil samples, an experiment with maize plants was also carried out to determine the plant dry matter production and the absorption of P. It was observed higher levels of occluded Pi and residual Po in the Hapludox. The fertilization also increased the contents of these fractions indicating that P is incorporated to the less available fractions. Therefore, the available P contents were smaller in this soil. In the Hapludult, Fe bound Pi and humic acids associated Po were the predominant P forms. The added P was incorporated into the Al and Fe bound P forms, which contributed to higher P availability in this soil. The more stable fractions of both Pi and Po did not correlate with available P, and the less stable fractions correlated with accumulated dry matter and P uptook by plants, indicating that even having a higher P content, the more stable fractions contribute in a more limited way to the P uptake by plants. In the Hapludox, the increase of Al, Fe bound P in the triple superphosphate treatment was crucial for greater availability. In the Hapludult, the increase of Al, Fe bound P, with lower occlusion of P in cattle manure treatment, resulted in higher availability. The interaction between the soil and fertilizer type defined the fate of the applied P, as well as the availability / FAPESP 2014/11466-3
26

Influência das variações da temperatura na produção de biogás em biodigestores modelo Bioköhler protegido com estufa plástica / Influence of the temperature variations in the production of biogas in Bioköhler biodigesters covered with greenhouse plastic film

Soares, Caroline Monique Tietz 25 February 2016 (has links)
Made available in DSpace on 2017-07-10T17:44:37Z (GMT). No. of bitstreams: 1 Caroline_Monique_Tietz_Soares.pdf: 2157190 bytes, checksum: 32d21cdfdc58d09a662671da5cc6fa2f (MD5) Previous issue date: 2016-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The anaerobic digestion process has been applied for the treatment of effluents both in developed countries as well as underdeveloped countries. Amongst the most predominant factors that affect the efficiency of this process is the temperature, considering the microorganisms development and the biogas production constitutes the temperature biodigester operational function. This study aimed at verifying the influence of temperature variation in the production of biogas from dairy cattle manure, in a Bioköhler biodigester covered with greenhouse plastic film. The experiment was performed in a 20 m3 biodigester located in the Antonio Carlos dos Santos Pessoa Experimental Station belonging to UNIOESTE Marechal Cândido Rondon Campus, during the period between 08/03/2014 to 02/07/2015. Data from the internal biodigester temperature and the greenhouse was obtained in conjunction with the external biodigester temperature, affluent and effluent density, total solid values, fixed and volatile, biogas volume produced and the concentration of CH4 present in this biogas. The results indicated that the microorganisms acted in the mesophilic layer and there was the indication that the production of biogas was influenced by temperature variability, nevertheless, the greenhouse avoided sudden alterations at this temperature. The results also evidenced that the medium capacity expected in the production of biogas surrounded 12 m3 per day and came across with an average of 57,33% of CH4 in this biogas. There was satisfactory volatile solid removal / O processo de digestão anaeróbia tem sido aplicado para o tratamento de efluentes tanto em países desenvolvidos como naqueles em desenvolvimento. Dentre os fatores mais importantes que afetam a eficiência deste processo está a temperatura, pois o desenvolvimento dos micro-organismos e a produção de biogás é função da temperatura operacional do biodigestor. Este trabalho buscou verificar a influência das variações da temperatura na produção de biogás a partir de dejetos da bovinocultura de leite, em biodigestor Bioköhler protegido por uma estufa plástica. O experimento foi realizado em um biodigestor de 20 m3 localizado na Estação Experimental Antonio Carlos dos Santos Pessoa, pertencente à UNIOESTE Campus de Marechal Cândido Rondon, no período de 03/08/2014 a 07/02/2015. Foram obtidos dados de temperatura interna ao biodigestor e a estufa, bem como de temperatura externa ao biodigestor, densidade dos afluentes e efluentes, valores de sólidos totais, fixos e voláteis, volume de biogás produzido e teor de CH4 presente neste biogás. Os resultados indicaram que os micro-organismos atuaram na faixa mesofílica e houve indício de que a produção de biogás foi influenciada pela variabilidade da temperatura, entretanto, a estufa evitou alterações bruscas nesta temperatura. Os resultados também evidenciaram que a capacidade média esperada de produção de biogás esteve em torno de 12 m3 por dia e obteve-se uma média de 57,33% de CH4 neste biogás. Houve remoção de sólidos voláteis e esta foi satisfatória
27

Tratamento da fração líquida de estrume bovino em reator anaeróbio híbrido em escala piloto / Treatment of liquid fraction of dairy manure in a pilot-scale anaerobic hybrid reactor

Pâmela Castilho Dias 06 October 2017 (has links)
O presente trabalho teve como principal objetivo avaliar o desempenho de um reator anaeróbio híbrido (RAnH) em escala piloto no tratamento da fração líquida de estrume bovino, visando à remoção de matéria orgânica e à produção de biogás. O RAnH estudado apresentava volume total 6,2 m3 e foi composto por manta de lodo, na qual a biomassa encontrava-se suspensa, e leito fixo, no qual utilizou-se Biobob® como material suporte para imobilização da biomassa. Para dar suporte a partida do RAnH, a água residuária em estudo foi submetida a teste de biodegradabilidade visando avaliar a influencia da inoculação do reator no potencial de biodegradabilidade e de produção de metano. No teste, a inoculação mostrou-se adequada, apresentando biodegradabilidade de 57 ± 4% e produção de metano de 344 ± 26 mL CH4. g SV-1. A operação do RAnH foi realizada por 260 dias e foi dividida em duas etapas: etapa inicial, na qual se procedeu a adequação da operação do reator, e etapa experimental, na qual se avaliou o desempenho do reator perante o aumento progressivo da carga orgânica aplicada. Durante a operação do reator foi alcançada a aplicação de COV bruta total de 25,50 ± 2,53 kg DQO.m-3.d-1 e a COV solúvel total de 7,69 ± 0,02 kg DQO.m-3.d-1, sendo atingido o TDH de 1,27 ± 0,004 d. O RAnH apresentou eficiência de remoção média de 65 ± 4 % durante a etapa experimental. A produção média de metano foi de 0,310 ± 0,095 m3 CH4. m-3.d-1 e 0,098 ± 0,018 m3 CH4. kg SVad, com 89 ± 3% de metano na composição do biogás. O potencial de produção de energia elétrica estimada com base no reaproveitamento metano produzido no RAnH foi de 0,89 kWh.m-3. O aproveitamento desta energia em sistema com vazão de 3.500 m3.d-1 geraria energia suficiente para abastecer 615 residências e uma economia mensal de R$ 11.835,09. / The main objective of this work was to evaluate the performance of a pilot-scale anaerobic hybrid reactor (RAnH) in the treatment of the liquid fraction of dairy manure, in order to remove organic matter and produce biogas. The applied RAnH had a total volume of 6.2 m3 and was composed of sludge blanket, in which the biomass was suspended, and fixed bed, in which Biobob® was applied as a support material for biomass immobilization. In order to support RAnH startup, the wastewater under study was submitted to a biodegradability test to evaluate the influence of reactor inoculation on the biodegradability potential and methane production potential. In the test the inoculated condition presented appropriate biodegradability (57 ± 4%) and higher methane production potential (344 ± 26 mL CH4.gVS-1). The RAnH operation was performed for 260 days and was divided into two stages: initial stage, in which the reactor operation was adjusted, and the experimental stage, in which the reactor performance was evaluated with the progressive increase of the applied organic load. During the reactor operation was reachead total raw VOC application of 25.50 ± 2.53 kg COD m-3.d-1 and total soluble VOC of 7.69 ± 0.02 kg COD m-3.d-1, with the HRT of 1.27 ± 0.004 d. The RAnH presented average removal efficiency of 65 ± 4% during the experimental stage. The average methane production was 0.310 ± 0.095 m3 CH4.m-3.d-1 and 0.098 ± 0.018 m3 CH4. kg VSad, with 89 ± 3% of methane in the biogas composition. The potential of electric energy production estimated based on the reuse of the methane produced in the RAnH was 0,89 kWh.m-3. The use of this energy in a system with a flow of 3,500 m3.d-1 would generate sufficient energy to supply 615 homes and a monthly saving of R$ 11,835.09.
28

Enhanced Biological Phosphorus Removal for Liquid Dairy Manure

Hong, Yanjuan 10 January 2010 (has links)
Enhanced biological phosphorus removal (EBPR) has been widely used in municipal wastewater treatment, but no previous studies have examined the application of EBPR to treat dairy manure. This study was conducted to evaluate the (i) performance of pilot-scale EBPR systems treating liquid dairy manure, to balance the ratio of nitrogen to phosphorus in manure to meet crop nutrient requirements, (ii) effects of dissolved oxygen and solids retention time on the efficiency of EBPR, and (iii) effectiveness of gravity thickening for reducing the volume of harvested EBPR aerated mixed liquor. Two pilot-scale EBPR systems were used in this study. The ratio of the manure chemical oxygen demand expressed as volatile fatty acids to phosphorus used ranged from 18:1 to 45:1. The phosphorus removal efficiencies of the EBPR system were investigated at three solids retention times (4, 6 and 10 d), and three dissolved oxygen levels (3, 4 and 6 mg O₂/L). The total phosphorus removal was highest (84%) at 10 d solids retention time and lowest (63%) at 4 d solids retention time. The sludge from the 6 d solids retention time tests had better sludge settling characteristics with a sludge volume index of 62 mL/g compared to 80 mL/g for the 4 d solids retention time. The EBPR system achieved 90% dissolved reactive phosphorus removal when the system was operated at 4 mg O₂/L, and the ratio of nitrogen to phosphorus in effluent increased to about 5:1, which was higher than the normal ratio in dairy manure. On the other hand, phosphorus removal performance deteriorated when dissolved oxygen level was 3 mg O₂/L. In the gravity thickening tests, 93-95 % total suspended solids (TSS) was removed from the settled supernatant, with 1.2 to 1.54 % total solids (TS) in the settled solids after 90 min gravity-induced thickening. The extent of phosphorus release during gravity thickening process needs to be further investigated. / Master of Science
29

The Effect of Thermophilic Anaerobic Digestion on Ceftiofur and Antibiotic Resistant Gene Concentrations in Dairy Manure

Howes, Sasha Alyse 06 July 2017 (has links)
The prevalence of antibiotics on farms for therapeutic and prophylactic use in animals can cause negative effects on biomethane production during anaerobic digestion. Previous literature has found decreased biomethane production rates from a variety of antibiotics, but biogas inhibition differs between studies of continuous and batch reactors and the type of antibiotic studied. Cephalosporin drugs are the most common antibiotic class used to treat mastitis in dairy cows and can retain most of their bioactivity after excretion. Ceftiofur is a commonly used cephalosporin drug but no previous study investigating the effect of Ceftiofur on biomethane during continuous anaerobic digestion has been performed. The aim of this study was to examine the effect on biomethane production when manure from cows treated with Ceftiofur was anaerobically digested. Laboratory sized anaerobic digesters (AD) were run at thermophilic (55°C) temperatures and a 10 day hydraulic retention time. Manure from cows treated with Ceftiofur were fed to the antibiotic treatment reactors for 50 days. The reactor performance was measured by i) biomethane production, ii) waste stabilization in terms of solids and chemical oxygen demand, iii) change in mass of Ceftiofur and iv) change in concentration of antibiotic resistant genes, specifically cfx(A), mef(A), and tet(Q). There was statistically significant decrease in cumulative gas production due to the addition of Ceftiofur into the reactors, but no significant difference between treatments in waste stabilization in terms of percent volatile solids (VS) and total chemical oxygen demand (TCOD) reduction. Anaerobic digestion decreased the amount of Ceftiofur in manure, and the amount of Ceftiofur in the reactors reduced over the time of the experiment. Change in antibiotic resistant genes (ARGs) were gene dependent over time. Concentrations of tet(Q) reduced significantly between feed and effluent of both treatments, and cfx(A) reduced significantly for the control treatment but not the Ceftiofur treatment. Concentrations of mef(A) increased over time in both treatments. Overall, the addition of Ceftiofur in continuously operated anaerobic digesters negatively affected biomethane production, a value-added product responsible for on-farm renewable energy. However, anaerobic digestion does decrease the mass of Ceftiofur within manure, thereby reducing the environmental loading from run-off from farms. / Master of Science
30

Impact of Manure Land Management Practices on Manure Borne Antibiotic Resistant Elements (AREs) in Agroecosystems

Hiliare, Sheldon 03 February 2021 (has links)
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.

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