The effectiveness of partial ozonation of return activated sludge for enhancing denitrification and waste sludge minimization were examined. A pair of nitrifying sequencing batch reactors was operated in either aerobic or alternating anoxic/aerobic conditions, with one control and one ozonated reactor in each set. The amount of solids decreased with the ozone dose. Biomass in the anoxic/aerobic reactor was easier to destroy than in the aerobic one, generating approximately twice as much soluble chemical oxygen demand (COD) by cell lysis. Increased COD favoured production of extracellular polymers in ozonated reactors, enhancing flocculation and improving settling. Floc stability was also strengthened in prolonged operation in alternating treatment, resulting in declined solids destruction. Dewaterability was better in alternating reactors than in aerobic ones indicating that incorporation of an anoxic zone for biological nutrient removal leads to improvement in sludge dewatering. The negative impact of ozonation on dewaterability was minimal in terms of the long-term operation. Ozone successively destroyed indicator estrogenic compounds, contributing to total estrogen removal from wastewater. Denitrification rate improved up to 60% due to additional carbon released by ozonation. Nitrification rates deteriorated much more in the aerobic than in the alternating reactor, possibly as a result of competition created by growth of heterotrophs receiving the additional COD. Overall, ozonation provided the expected benefits and had less negative impacts on processes in the alternating treatment, although after prolonged operation, benefits could become less significant. The alternating anoxic/aerobic reactor achieved twice the nitrification rates of its aerobic counterpart. Higher removal rates of estrogens were associated with higher nitrification rates, supporting the contention that the nitrifying biomass was responsible for their removal. The alternating treatment offered the better estrogen biodegradation. Microbial populations in both reactors were examined with fluorescent in situ hybridization. Dominance of rapid nitrifiers like Nitrosomonas and Nitrobacter (79.5%) in the alternating reactor, compared to a dominance of slower nitrifiers like Nitrosospira and Nitrospira (78.2%) in the aerobic reactor were found. The findings are important to design engineers, as reactors are typically designed based on nitrifiers’ growth rate determined in strictly aerobic conditions.

Two laboratory incubation studies and a growth room bioassay of forage barley were conducted to investigate nitrogen (N) and phosphorus (P) mineralization, and nitrous oxide emission from two contrasting agricultural soils amended with anaerobically digested cattle manure (ADM). The ADM is a nutrient-rich co-product from manure-based biogas plants which is applied to cropland at rates used for raw manure since scientific information on nutrient release from ADM is lacking. Application of the separated solids fraction of ADM (SS) reduced nitrous oxide emission but resulted in lower N mineralization compared to raw manure in both soils. Raw manure- and SS- treatments had similar biomass yields and P supply capacities while the application of pelletized SS (PSS) caused net N immobilization, lower P release than manure and SS, and depressed barley yields relative to non-amended (control) soils.

The ocean is the most extended biome present on our planet. Recent decades have seen a dramatic increase in the number and gravity of threats impacting the ocean, including discharge of pollutants, cultural eutrophication and spread of alien species. It is essential therefore to understand how different impacts may affect the marine realm, its life forms and biogeochemical cycles. The marine nitrogen cycle is of particular importance because nitrogen is the limiting factor in the ocean and a better understanding of its reaction mechanisms and regulation is indispensable. Furthermore, new nitrogen pathways have continuously been described. The scope of this project was to better constrain cause-effect mechanisms of microbially mediated nitrogen pathways, and how these can be affected by biotic and abiotic factors. This thesis demonstrates that meiofauna, the most abundant animal group inhabiting the world’s seafloors, considerably alters nitrogen cycling by enhancing nitrogen loss from the system. In contrast, larger fauna such as the polychaete Marenzelleria spp. enhance nitrogen retention, when they invade eutrophic Baltic Sea sediments. Sediment anoxia, caused by nutrient excess, has negative consequences for ecosystem processes such as nitrogen removal because it stops nitrification, which in turn limits both denitrification and anammox. This was the case of Himmerfjärden and Byfjord, two estuarine systems affected by anthropogenic activities, such as treated sewage discharges. When Byfjord was artificially oxygenated, nitrate reduction mechanisms started just one month after pumping. However, the balance between denitrification and nitrate ammonification did not favor either nitrogen removal or its retention. Anoxia is also present in aggregates of the filamentous cyanobacteria Nodularia spumigena. This thesis shows that even in fully oxic waters, millimetric aggregates can host anaerobic nitrogen processes, with clear implications for the pelagic compartment. While the thesis contributed to our knowledge on marine nitrogen cycling, more data need to be collected and experiments performed in order to understand key processes and regulation mechanisms of element cycles in the ocean. In this way, stakeholders may follow and take decisions in order to limit the continuous flow of human metabolites and impacts on the marine environment. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.</p>

This study explores the possibility of utilizing bioleaching techniques for nickel extraction from a mixed sulfide ore deposit with high magnesium content. Due to the ultramafic nature of this material, well-studied bioleaching technologies, which rely on acidophilic bacteria, will lead to undesirable processing conditions. This is the first work that incorporates nitrate-dependent bacteria under pH 6.5 environments for bioleaching of base metals. Experiments with both defined bacterial strains and indigenous mixed bacterial cultures were conducted with nitrate as the electron acceptor and sulfide minerals as electron donors in a series of microcosm studies. Nitrate consumption, sulfate production, and Ni released into the aqueous phase were used to track the extent of oxidative sulfide mineral dissolution; taxonomic identification of the mixed culture community was performed using 16S rRNA gene sequencing. Nitrate-dependent microcosms that contained indigenous sulfur- and/or iron-oxidizing microorganisms were cultured, characterized, and provided a proof-of-concept basis for further bioleaching studies.

The effectiveness of partial ozonation of return activated sludge for enhancing denitrification and waste sludge minimization were examined. A pair of nitrifying sequencing batch reactors was operated in either aerobic or alternating anoxic/aerobic conditions, with one control and one ozonated reactor in each set. The amount of solids decreased with the ozone dose. Biomass in the anoxic/aerobic reactor was easier to destroy than in the aerobic one, generating approximately twice as much soluble chemical oxygen demand (COD) by cell lysis. Increased COD favoured production of extracellular polymers in ozonated reactors, enhancing flocculation and improving settling. Floc stability was also strengthened in prolonged operation in alternating treatment, resulting in declined solids destruction. Dewaterability was better in alternating reactors than in aerobic ones indicating that incorporation of an anoxic zone for biological nutrient removal leads to improvement in sludge dewatering. The negative impact of ozonation on dewaterability was minimal in terms of the long-term operation. Ozone successively destroyed indicator estrogenic compounds, contributing to total estrogen removal from wastewater. Denitrification rate improved up to 60% due to additional carbon released by ozonation. Nitrification rates deteriorated much more in the aerobic than in the alternating reactor, possibly as a result of competition created by growth of heterotrophs receiving the additional COD. Overall, ozonation provided the expected benefits and had less negative impacts on processes in the alternating treatment, although after prolonged operation, benefits could become less significant. The alternating anoxic/aerobic reactor achieved twice the nitrification rates of its aerobic counterpart. Higher removal rates of estrogens were associated with higher nitrification rates, supporting the contention that the nitrifying biomass was responsible for their removal. The alternating treatment offered the better estrogen biodegradation. Microbial populations in both reactors were examined with fluorescent in situ hybridization. Dominance of rapid nitrifiers like Nitrosomonas and Nitrobacter (79.5%) in the alternating reactor, compared to a dominance of slower nitrifiers like Nitrosospira and Nitrospira (78.2%) in the aerobic reactor were found. The findings are important to design engineers, as reactors are typically designed based on nitrifiers’ growth rate determined in strictly aerobic conditions.

Two laboratory incubation studies and a growth room bioassay of forage barley were conducted to investigate nitrogen (N) and phosphorus (P) mineralization, and nitrous oxide emission from two contrasting agricultural soils amended with anaerobically digested cattle manure (ADM). The ADM is a nutrient-rich co-product from manure-based biogas plants which is applied to cropland at rates used for raw manure since scientific information on nutrient release from ADM is lacking. Application of the separated solids fraction of ADM (SS) reduced nitrous oxide emission but resulted in lower N mineralization compared to raw manure in both soils. Raw manure- and SS- treatments had similar biomass yields and P supply capacities while the application of pelletized SS (PSS) caused net N immobilization, lower P release than manure and SS, and depressed barley yields relative to non-amended (control) soils.

Graduation date: 1993

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv., 2003. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 3 uppsatser.

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No. of bitstreams: 1 chaucanes_pam_me_ilha.pdf: 4074329 bytes, checksum: b4e87799b76f0a2635d5a1511a22d2f0 (MD5) Previous issue date: 2017-10-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este estudo mostra o funcionamento dos processos de oxidação de matéria orgânica junto com os processos simultâneos de nitrificação e desnitrificação (SND) dentro do reator aeróbio de leito fluidizado de tubos concêntricos com uma terceira câmara para gerar condições anóxicas (necessárias para garantir o processo de desnitrificação). O reator foi operado por um período de 140 dias, durante o qual a remoção de demanda química de oxigênio (DQO) e de nitrogênio total (NT), atingiu 80% e 44% respectivamente, para um tempo de detenção hidráulica (TDH) de 3 horas. A configuração dos diâmetros dos tubos concêntricos resultou em diferentes relações de áreas e, portanto em diferentes vazões para cada câmara. Na operação do reator foram aplicadas duas relações de vazões alterando o nível de esgoto dentro do reator. Os efeitos destas relações de vazões, alterou a concentração de oxigênio dissolvido (OD) entre os compartimentos aeróbio e anóxico do reator e a relação C:N, as quais foram estudadas durante o funcionamento deste sistema. Os resultados indicaram que a relação de vazões 2(4,8: 3,8: 1 para as câmaras 1, 2 e 3, respectivamente) beneficiou as remoções de DQO e NT. A concentração de OD no compartimento aeróbio apresentou valores médios de 3,57 ± 1,24 mg.L -1 , e no topo da câmara 3, a concentração de OD foi de 1,41 ± 0,78 mg.L -1 . As relações C:N que apresentaram maiores eficiências de remoção de NT foram as superiores a 10, sendo a máxima remoção de T na relação C:N de 17. O tempo de retenção celular (TRC) alcançado no reator foi de 3,16 ± 3,07 dias. Neste trabalho de pesquisa foi concluído que a configuração de três câmaras concêntricas para o reator aeróbio de leito fluidizado beneficia a remoção de NT, tornando este reator uma alternativa para o tratamento de águas residuárias domésticas. / This study shows the operation of the organic matter oxidation processes together with the simultaneous processes of nitrification and denitrification (SND) inside the aerobic fluidized bed reactor of concentric tubes with a third chamber to generate anoxic conditions (necessary to guarantee the denitrification process). The reactor operated over a period of 140 days, during which chemical oxygen demand (COD) and total nitrogen (TN) removal reached 80% and 44% respectively, for a 3 hour hydraulic detention time (HDT). The configuration of the diameters of the concentric tubes resulted in different area ratios and therefore in different flow rates for each chamber. In the reactor operation were applied two flow ratios, altering the sewage level inside the reactor. The effects of these flow rates were changing the concentration of dissolved oxygen (DO) between the aerobic and anoxic compartments of the reactor and the C: N ratio, which was studied during the operation of this system. The results indicated that the ratio of flows 2 (4.8: 3.8: 1 for chambers 1, 2 e 3, respectively) benefited the COD and TN removal. The DO concentration in the aerobic compartment presented average values of 3.57 ± 1.24 mg.L-1 , and on top of chamber 3, the DO concentration was 1.41 ± 0.78 mg.L-1 . The C:N ratios that showed higher nitrogen removal efficiencies were higher than 10, with the maximum TN removal at the C:N ratio of 17. The cell retention time reached (CRT) in the reactor was 3.16 ± 3.07 days. In this research, was concluded that three concentric chambers configuration for the aerobic fluidized bed reactor benefits the TN removal, became this reactor an alternative in domestic wastewater treatment.