Effect of ammonia load on efficiency of nitrogen removal in an SBBR with liquid-phase circulation

The removal of biological nitrogen from a synthetic wastewater with different ammonium nitrogen concentrations (50 and 100 mgN-NH4+/L) by a nitrification and denitrification process using a sequencing batch biofilm reactor (SBBR) with liquid-phase circulation was studied. The system with a total working volume of 4.6 L (3.7 L in the reactor and 0.9 L in the reservoir) treated 2.1 L of synthetic wastewater in 12-h cycles. As inoculum two types of biomass were used: an anaerobic/anoxic one from an up-flow anaerobic sludge blanket reactor (UASB) and an aerobic one from a prolonged aeration activated sludge system. The system, maintained at 30 ± 1 ºC, operated in batch mode followed by fed-batch mode and was aerated intermittently. During fed-batch operation the reactor was fed with an external carbon source as electron donor in the denitrifying step and with no aeration. When the reactor was fed with 50 mgN-NH4+/L, efficiencies of removal of ammonium nitrogen and total nitrogen from the effluent were 93.8 and 72.2%, respectively, and nitrite, nitrate and organic nitrogen concentrations were 0.07, 6.4 and 0.5 mg/L, respectively. On the other hand, when the influent ammonium nitrogen concentration was 100 mgN-NH4+/L, residual nitrite and nitrate were 0.17 and 20.4, respectively, and no N-Org was found in the effluent. It should be mentioned that residual nitrate remained unaltered at the different C/N ratios used. Consequently, efficiency of total nitrogen removal was reduced to 66.7%, despite efficiency of ammonium nitrogen removal exceeding 90%. These results show the potential of the proposed system in removing ammonium nitrogen from liquid effluents with a moderate ammonium nitrogen concentration.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Effect of bicarbonate alkalinity on gravimetric solids analysis in anaerobic wastewater treatment

Bicarbonate alkalinity plays an important role in the stability of biological reactors used in wastewater treatment, primarily in anaerobic systems. As some wastewaters tend to acidify readily, addition of an external alkali source may be necessary to maintain process stability. An assessment was made of the effect of sodium bicarbonate addition on the determination of solids concentration. The methodology consisted in accompanying a series of solids concentrations (total solids, TS; total volatile solids, TVS; and total fixed solids, TFS) in samples containing cheese whey and volatile acids used to simulate anaerobic reactor effluents. TS, TVS and TFS showed to be strongly affected by NaHCO3 addition, mainly due to an increase in TFS. This effect could be quantified by relating the experimental values to the theoretical ones from the stoichiometric equations for NaHCO3 decomposition and other compounds (sodium acetate and sodium propionate) formation with temperature increase. In this way, as one of the main parameters of assessing liquid effluent treatment systems is the reduction in solids present in the medium, the concentration of solids can be quantified more adequately by determining fixed solids from the inorganic salts present. This methodology showed to be adequate in cases where a significant amount of alkali is added.32961061

System reconfiguration for cylindrical laser cladding application

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2019Componentes cilíndricos são comuns em aplicações industriais e muitos deles exigem tratamentos especiais para prolongar sua vida útil. O revestimento de superfícies via laser cladding foi reconhecida como sendo significativamente benéfica em relação às técnicas convencionais. No entanto, esse processo ainda exige pesquisa e desenvolvimento, por exemplo, a superfície recoberta pode apresentar desvios indesejáveis, tanto geométricos como de forma. Neste contexto, a cinemática do equipamento e a estratégia de deposição são centrais para a qualidade do revestimento. Infelizmente, as linhas de pesquisa e desenvolvimento de materiais com laser no Brasil sofrem com a falta de instalações adequadas para lidar com aplicações de alta potência, mesmo havendo uma demanda representativa deste campo. Neste sentido, o alto custo de equipamentos comerciais requer o desenvolvimento de sistemas laser pelos próprios institutos. Desde 2010, o Laboratório de Mecânica de Precisão (LMP) começou a atuar em pesquisas de processamento a laser. O sistema laser até então disponível tinha a capacidade de operar em três eixos de movimento simultâneo em uma configuração XYZ linear ? adequado para superfícies planas. Este trabalho busca a reconfiguração do sistema laser para interpolação cilíndrica, a fim de permitir a aplicação de revestimentos em superfícies de revolução externamente. Na primeira parte do trabalho é apresentada uma contextualização da tecnologia laser, histórico, definição, aplicações e normas de segurança. Nesta fase ainda, o processo de recobrimento, ou laser cladding é destacado, assim como as superligas e os equipamentos que utilizados para a sua aplicação. Em seguida é a presentada uma revisão sobre sistemas modulares. Na sequência, a metodologia de projetos para sistemas mecânicos de precisão reconfiguráveis, que será utilizada neste trabalho, é descrita e tem suas etapas detalhadas. Após a descrição da metodologia, segue-se sua aplicação. A primeira fase do projeto em questão consiste na implementação da metodologia para orientar o aprimoramento do equipamento e satisfazer os requisitos iniciais do projeto. Em seguida, a construção do equipamento é apresentada, onde os novos módulos necessários foram integrados ao sistema existente por meio de interfaces, preservando as capacidades originais de acordo com a metodologia. Na última fase, após alguns ensaios metrológicos, foram aplicados os revestimentos de INCONEL 625, primeiramente sobre placas planas de aço AISI 1020 e, posteriormente, sobre um substrato cilíndrico. A seção transversal das deposições foi analisada para avaliar a consistência geométrica da aplicação. Os resultados obtidos por meio da avaliaçãometrológica e das aplicações em condições reais demonstraram a competência do sistema de interpolação para guiar o sistema laser em trajetórias cilíndricas. O aprimoramento do equipamento permite que novas linhas de pesquisa sejam exploradas, não somente em recobrimento de superfícies cilíndricas, mas também, por exemplo, soldagem de tubos a laser e inclusive aplicações em materiais reflexivos ? em virtude da possibilidade de rotação do cabeçote laser. Finalmente, são listadas algumas melhorias e sugestões para trabalhos futuros.Abstract: Cylindrical components are common on industrial applications and many of them requires coating protection to extend its lifetime. The application of protective coatings via laser cladding was recognized to be significantly beneficial over conventional techniques. However, this process still demands research and development, for instance, the resultant surface can present undesirable geometric and form deviations. In this context, the equipment kinematics and the deposition strategy are central to the cladding quality. Unfortunately, the Brazilian R&D on laser materials processing suffers from the lack of adequate facilities to deal with high power laser applications, even so, there is a considerable demand for this field. In this sense, the high cost of commercial equipment requests the development of laser systems by the own institutes. Since 2010, the Precision Engineering Laboratory (LMP) started researching laser applications. The current Laser System available is capable of three axes simultaneous movement on a XY table setup - suitable for flat surfaces. This work seeks the Laser System reconfiguration for cylindrical interpolation in order to produce laser cladding application externally on revolution surfaces. The first phase consists of a project methodology implementation to orientate the equipment upgrade to satisfy the requirements. Then, the new modules necessary were integrated in the existent system via proper interfaces preserving the original capabilities. In the last phase, after some metrological tests, INCONEL 625 clads were applied, first over AISI 1020 flat plates and after that, over a cylindrical substrate. The cross section of the cladded layers were analyzed to evaluate the clad geometry consistence. The results testified the interpolation competence to guide the laser cladding system for cylindrical trajectories also allowing the research team to prospect more laser processes

Effect of specific feed volume on the performance of an anaerobic sequencing batch biofilm reactor (AnSBBR) with circulation treating diferent wastewaters under different organic loads

The objective of this research was to study the behavior of two anaerobic sequencing batch reactors, containing immobilized biomass (AnSBBR), as a function of the ratio of the volume of treated medium in each cycle to the total volume of reaction medium. The reactors, in which mixing was accomplished by recirculation of the liquid phase, were maintained at 30 ± 1 ºC and treated different wastewaters in 8-h cycles. The operational conditions imposed had the objective to investigate whether maintenance of a residual volume in the reactor would affect, at the end of each cycle, process efficiency and stability, as well asto verify the intensity of the effect for different types of wastewaters and organic loading rates. The first reactor, with work volume of 2.5 L, treated reconstituted cheese whey at an organic loading rate of 12 g COD·L-1·d-1 and presented similar effluent quality for the four conditions under which it was operated: renewal of 100, 70, 50 and 25 % of its work volume at each cycle. Despite the fact that reduction in the renewed volume did not significantly affect effluent quality, in quantitative terms, this reduction resulted in an increase in the amount of organic matter removed by the first reactor. The second reactor, with work volume of 1.8 L, treated synthetic wastewater at organic loading rates of 3 and 5 g COD·L-1·d-1 and operated under two conditions for each loading: renewal of 100 and 50 % of its work volume. At the organic loading rate of 3 g COD·L-1·d-1, the results showed that both effluent qualityand amount of organic matter removed by the second reactorwere independent of the treated volume per cycle.At the organic loading rate of 5 g COD·L-1·d-1, although thereduction in the renewed volume did not affect the amountof organic matter removed by the reactor, effluent qualityimproved during reactor operation with total discharge of its volume. In general, results showed process stability under all conditions, evidencing reactor flexibility and the potential to apply this technology in the treatment of different types of wastewater