Orientador: Benedito Carlos Benedetti / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-06T18:41:51Z (GMT). No. of bitstreams: 1 Teixeira_GilmarValente_M.pdf: 1086398 bytes, checksum: 977e54e017a68937e4ccdcbc30d550dc (MD5) Previous issue date: 2001 / Resumo: À medida que a globalização é uma realidade mundial e aumenta a competitividade de abastecimento de alimentos, e sendo o Brasil um país tradicionalmente agrícola, torna-se uma prioridade produzir e armazenar cada vez melhor. Nestes processos a qualidade da matéria prima é fundamental pois os produtos alimentares apresentam sua qualidade condicionada à qualidade da matéria-prima que lhes deu origem. O armazenador de grãos deve ter como objetivo principal a preservação da qualidade dos produtos sob sua responsabilidade. Portanto, entender como as perdas ocorrem durante o armazenamento com e sem sistema de aeração, em diferentes níveis de umidade; verificar a variação do teor de óleo, proteína e acidez e obter modelos matemáticos para prever o comportamento da soja em função dos indicadores de qualidade foram os objetivos do trabalho. Armazenou-se soja durante 238 dias com três teores iniciais de umidade (12,70; 14,50 e 15,50% b.u.), em silos metálicos, sendo que 9 silos com sistema de aeração e 9 silos sem sistema de aeração. A temperatura foi registrada e amostras de grãos coletadas. Modelos de regressão foram ajustados em função do período de armazenamento e do teor de umidade inicial. A deterioração da soja ocorrida durante o experimento (aumento do percentual de grãos ardidos, avariados e teor de acidez do óleo) foi visualizada, principalmente, nos silos sem sistema de aeração, onde observou-se a presença de fungos com maior proliferação para a soja com teor de umidade inicial de 15,50%. Podemos dizer, portanto, que o armazenamento com sistema de aeração preservou melhor a qualidade da soja independentemente do teor de umidade inicial. Por outro lado, para o armazenamento sem sistema de aeração a deterioração ocorreu em função do teor de umidade inicial. Sendo assim, concluiu-se que: As perdas ocorridas foram constatadas principalmente devido ao aumento do teor de grãos ardidos e grãos avariados e se acentuam no teor de umidade inicial mais alto (15,50%), no armazenamento sem sistema de aeração; As variações do teor de proteína e teor de óleo são independentes do uso ou não do sistema de aeração; O teor de óleo tem tendência a decrescer com o tempo de armazenamento, sendo função do teor de umidade inicial e do tempo de armazenagem; Os modelos matemáticos obtidos, ou as respectivas superfícies de resposta, podem ser usados para estimar os parâmetros teor de umidade, teor de ardidos, teor de proteína e teor de óleo ao longo do armazenamento; A amostragem de grãos em processo de deterioração, utilizando-se o calador, necessita de cuidados especiais, com adaptações para obter-se uma amostra representativa / Abstract: As the globalization is a world reality and it increases the contest of food provisioning, and being Brazil a traditionally agricultural country, it has become priority to produce and to store better and better. The concern with the quality is big, because the alimentary products present their quality conditioned to the raw material quality that gave them origin. Someone in charge of the storage of products should have as main objective the preservation of the quality of the grain that entered in the unit. Therefore, being able to understand how the losses happen during the storage with and without aeration system in different moisture levels, verifying the variation of oil level, protein and acidity and obtaining mathematical models to foresee the behavior of the soybeans in function of the quality indicators are the objectives of the work. Soybeans were stored with three initial levels of moisture, in silos with aeration system and silos without aeration system for 238 days. The temperatures data were registered and samples were collected. Mathematical models were adjusted according storage period and initial moisture content. The soybeans deterioration during the storage period (increased the heat damage, total damage and oil acid) was detected mainly on the silos without aeration system, where detect mainly molds on the soybeans with 15,5% initial moisture content. Therefore we can say that storage soybeans with aeration system preserved better the quality soybeans, independents of initial moisture content. On the other hand, the storage without aeration system the deterioration occurred in function of initial moisture content.We concluded that: The losses occurred were due mainly to the increase of heat damaged grains and damaged grains levels; The protein and oil levels variation were independents of the aeration use; The oil level trends to decrease during the storage, and is a function of the initial moisture content and the storage time; The obtained mathematical models, or the respective response surfaces, can be used to estimate the moisture content, heat damaged grains level, protein level and oil level during the storage;The sample process of grains in deterioration process, using the MA-450T sampler, must have special attention, with adaptations to obtain representative samples / Mestrado / Tecnologia Pós-Colheita / Mestre em Engenharia Agrícola

Doctor of Philosophy / Department of Grain Science and Industry / X. Susan Sun / With continued population growth, more food production will be required with lower resource inputs. A significant drain on resources is post-harvest loss due to insects, which results in loss of product, quality and market access, and increased grain spoilage. Aeration and fumigation are key tools to control insect growth in stored grains and grain foods. The implementation of aeration strategies in Australia is made difficult by the warm subtropical climate, meanwhile the success of fumigation is being threatened by the spread of insect resistance to the fumigant phosphine. This dissertation project seeks to improve the understanding of aeration and fumigation by modifying the Maier-Lawrence (M-L) 3D ecosystem model by adding insect growth equations and quantifying fumigant loss from sealed bulk grain silos. The improved model was used to examine aeration under Australian conditions, validate its capability to accurately describe fumigant concentrations during silo fumigation, determine the extent to which fumigations are influenced by operational variables and environmental conditions, and validate its capability to describe fumigant concentrations post-fumigation in order to investigate the time needed to clear a grain storage silo of fumigant in order to assure worker safety. Six aeration strategies were evaluated under Australian conditions. Of these strategies, two were found to be effective in lowering temperatures, i.e., fans were turned on when ambient temperature was less than 20oC, and less than internal grain temperature. The strategy based on temperature differential was the most effective because it cooled the interior of the grain mass with the least amount of energy (using the fewest fan run hours, and reaching 15oC an average of 11 days after than the fastest strategy). Using a 0oC temperature differential was the most effective strategy in terms of reducing insect growth. The expanded (M-L-P) model was then validated based on experimental fumigant concentrations. The model was effective in reproducing average fumigant concentrations and fumigant trends vertically through the grain mass, but was not able to reproduce lateral fumigant variations. Verifications of the model with two different periods of phosphine release (i.e., 24h and 30h) were tested. Based on a 24h phosphine release period the predicted Ct-product differed from the experimental value by 0.9%. A 30h release period predicted a Ct-product that differed by 4.3% from the experimental value but it was more accurate during the times of highest concentration. Increases in leakage reduced fumigant concentrations, but the size of the effect decreased as leakage grew. Increasing temperature and wind speed in the model led to decreased phosphine concentrations, with temperature changes having a more significant impact overall than wind speed changes for the conditions investigated. Decreasing silo surface area to volume ratio dampened the impact of changing weather conditions on phosphine concentrations. A fumigant venting experiment was conducted in a silo at Lake Grace, Australia, to investigate full scale desorption. Two equations estimating fumigant desorption were tested, with an average of 65.5% and -86.3% error. The length of venting periods was simulated to quantify hours needed to mitigate hazardous conditions. For the scenarios investigated 10 to 24 h of venting were needed to reduce residual fumigant concentration below 0.3 ppm depending on simulation assumptions.

Pharmaceutical compounds comprise a wide range of substances that are consumed in large quantities by modern societies and are generally released into local sewer networks through excretion. This research aimed to identify the factors affecting the removal efficiencies of these compounds in biological wastewater treatment plants (WWTPs) under different environmental conditions. Of the pharmaceutical compounds selected for this study, the highest influent concentrations measured in municipal wastewater treatment plants (MWWTPs) were for paracetamol, naproxen and bezafibrate (> 1 μg/L), followed by carbamazepine, atenolol, lidocaine, sulfamethoxazole and NACS (<1 μg/L). In hospital wastewater treatment plants (HWWTPs), the highest concentrations measured were for paracetamol and caffeine (> 10 μg/L), followed by ciprofloxacin and NACS (1–6 μg/L), and finally bezafibrate, carbamazepine, atenolol, lidocaine, clarithromycin and sulfamethoxazole (< 1μg/L). Antibiotic drugs were detected in HWWTPs, but rarely detected in MWWTPs. In general, the hospital wastewaters contained relatively higher levels of pharmaceuticals than municipal wastewaters. The removal efficiencies of the pharmaceutical compounds ranged widely. This was found to be related to characteristics and operational parameters of the individual WWTPs. The MWWTPs that utilized long aeration and biomass retention times (HRT,SRT), as evidenced by the occurrence of complete nitrification, were more efficient at removing paracetamol, naproxen, bezafibrate and atenolol, than the non-nitrifying plants with relatively shorter HRT and SRT. HWWTPs that operated under elevated ambient temperatures (> 26°C) achieved higher removal efficiencies (90%) for several compounds, including paracetamol, caffeine, sulfamethoxazole, ciprofloxacin, clarithromycin, NACS, atenolol, carbamazepine and lidocaine. In addition to the elevated ambient temperatures, elevated HRT and SRT and less dilution can lead to increased active biomass and can result in higher removal rates for the pharmaceutical compounds. Overall, the removal efficiencies of pharmaceuticals in WWTPs have been correlated to the type of treatment plant, the plants’ operational parameters (HRT, SRT), the climatic conditions (temperature and dilution effect of rainfall) and characteristics of the micropollutants (type and concentration). Aerobic and anaerobic batch biodegradation experiments were conducted to observe the removal of paracetamol, naproxen, ibuprofen and sulfamethoxazole at various SRTs. The biodegradation rates varied widely ranging from poor, to moderate, to high, depending on the SRT. Paracetamol was highly biodegradable under both aerobic and anaerobic conditions. Sulfamethoxazole was poorly biodegradable under aerobic conditions but highly biodegradable under anaerobic conditions. Relatively slow biodegradation rates were observed for ibuprofen and naproxen under both conditions; longer microbial adaptation periods for these two compounds were probably required. The most important factor affecting the removal of the compounds was the SRT. Therefore, the conclusion was drawn that combining anaerobic and aerobic systems with longer SRT and HRT could bring about significant reductions in the emissions of these contaminants into the environment via WWTPs; this is also a cost-effective option.

This PhD thesis experimentally studies the volumetric efficiency of gerotor pumps in aero-engine gas turbine oil systems. This efficiency is the ratio of the effective measured flow rate and the theoretical flow rate computed based on pump displacement. In case of low inlet pressure and high rotational speed, which is often the case in aeronautical applications, the pump performance is severely affected by cavitation. This phase change from liquid to vapour causes a large portion of the flow to be occupied by gas, reducing the volume available for the liquid and reducing the overall mass flow rate. Due to its nature, the lubrication oil used in gas turbine engines is subjected to aeration which is the dissolution of air in oil. The air is dissolved in the liquid at high ambient pressure and released at lower pressure causing more air to occupy the cavities inside the pump. The change in liquid aeration is a relatively slower phenomenon causing the variation of aeration to be delayed with respect to the actual pressure and therefore varying also accordingly to the previous oil condition.The essential part of the work presented in this thesis is based on experimental research realised at the ATM department. This was conducted on a dedicated oil system test rig. This rig is build to reproduce the complete set of operating conditions encountered in a flying embedded oil system. This test rig was modified and equipped with several specific measurement systems to acquire data on pump performance and oil aeration. Precisely, a series of single-phase performance characterisations and transients have been recorded. The oil aeration was measured with two density-based instruments. The pump outlet pressure was recorded with a high-frequency pressure transducer. A new set-up of the test rig was also developed to allow the testing of pumps in two-phase flows conditions. Two-phase flows performance characterisations and transients have then also been studied.The data processing provided information necessary to build empirical models and to understand pump and cavitation behaviours. The focus is on pump performance in cavitation. This justify the extensive use of the cavitation number indicating the tendency of a flow to experience cavitation in given conditions. The base models can be used to determine if a given condition leads to cavitation or not, and predict the pump efficiency in both cases. The high-frequency pressure measurements provided an efficient tool to detect cavitation. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

In this investigation, two separate methods for determining oxygen transfer rates were applied to the oxidation ditches of an activated sludge plant. Steady state oxygen uptake rate testing and an oxygen mass balance technique were used to propose an in-process procedure for monitoring aeration efficiency using available resources. Although some overall averages offered promise, the testing results revealed that the mass balance analysis yielded results that do not accurately represent the oxygen transfer capabilities within the individual reactors due to shared variables that control the oxygen transfer rate. The steady state method provided more favorable results. Overall averages of daily oxygen transfer rates determined using the steady state method displayed a ratio of oxygen transfer rate between the reactors that corresponds to the expected ratio of 5/6 derived from the linear feet of aerator rotor present in each reactor.

No description available.

The primary goal of this study was to evaluate a new device and system, designed to optimize the performance of standard low pressure air diffusers in two types of aerated systems (activated sludge and aerobic sludge digestion) and to decrease overall energy consumption. Aerated treatment systems are very important in the treatment of wastewaters and management of sludges. The activated sludge process is widely used to treat wastewater from both industrial and municipal sources. However, they are costly to operate because oxygen is marginally soluble in water and standard low pressure (8 psig) diffusers provide marginal mixing and minimum retention. The newly patented device is referred to as TotalMix and is a type of pneumatic mixing system. TotalMix introduces air under high pressure at regular fixed intervals. During the tests the frequency of air delivered, the pressure, and the period of pressured air delivery was varied manually or through feedback control to optimize oxygen transfer and the interaction with a regular aeration system. Various chemical parameters, most importantly dissolved oxygen, were measured and compared to the new approach, using the TotalMix in combination with standard diffuser systems. The new System was tested in different sized tanks (17,000 L and 380,000 L), different concentrations of total solids (TS), using different airflow rates and different diffusers (membrane fine bubble diffusers, ceramic fine bubble diffuser, and course bubble diffuser). The statistical evaluation of the experiments indicates an increase in oxygen transfer rate with a concomitant decrease in energy consumption at low airflow rates. / Master of Science

When evaluating the performance of horizontal rotor mechanical surface aeration equipment in accordance with the ASCE Standard for Measurement of Oxygen Transfer in Clean Water, several factors should be considered with regard to their impact on the reported performance. These include basin geometry and testing volume, source water quality, dissolved oxygen measurement location, and external environmental factors including air temperature and humidity. Each of these factors may influence the reported performance of mechanical surface aeration equipment, specifically horizontal rotor aeration devices, resulting in an inaccurate estimation of the true equipment performance that should be expected in practical applications.

No description available.

The presence of hydrogen sulfide in a ground water source is noted by its rather obnoxious odor, similar to a "rotten egg". Concentrations as low as 0.05 ppm are noticeable, therefore, almost its entire removal is demanded prior to potable consumption. Hydrogen sulfide is formed primarily by the decomposition of organic matter in anaerobic conditions. Removal of this gas has been accomplished by means of aeration, detention, and chlorination over the years. The mechanisms behind each of these processes are complex and discussed in this paper. During the course of this investigation, a literature survey concerning the mature and sources of hydrogen sulfide, its removal by aeration and detention, and the experimental methodology has been conducted. Samples were collected from two ground water locations in Central Florida, namely City of Apopka Terrace Plant, and the City of Maitland Thistle Plant. These samples were taken before and after aeration and detained in containers similar to the storage tank dimensions. These samples were tested for Hydrogen Sulfide and pH with respect to time. The aerators were determined to remove 13 to 15 percent H2S, respectively. The pH values ranged between 7 - 8 prior to detention and rose slowly during H2S ionization to 8-8.6. Both locations were evaluated to determine the most economic operating conditions. Ideally, Apopka should be removing between 30 - 40 percent by means of aeration, and Maitland, between 40 - 50 percent. Chlorination will remove the remaining H2S. Although the existing aerators were operating less than their optimum removal range, they should remain in service. This is based on deducting the aerator "sunk costs" from the economic evaluation. Efforts should be encouraged to improve aerator efficiencies by increased agitation, contact time, and weir overflow rates in the aerator trays. These measures should increase the H2S reaction rate and improve its removal. Detention only removes the odor problem, but the chlorine demand still remains, as exerted by the forms HS- and S=.