988 resultados para lime mud


Relevância:

10.00% 10.00%

Publicador:

Resumo:

The use of activated carbon powder (ACP), red mud and oxidation with chlorine to remove mefenamic acid in water are described, aimed at their application as a complement to sewage treatment processes in Brazil. A study on the behavior of mefenamic acid in water was performed by evaluating its dissolution for different concentrations and times. Subsequently, the optimal conditions for removal of mefenamic acid were investigated using ACP adsorption at different pH and concentrations, and red mud adsorption using different pH. The utilization of different pH and times was also investigated to establish the ideal conditions for chemical oxidation of the drug. Among the different conditions studied, the best condition for drug removal by ACP and red mud were 100% and 96%, respectively, while the best condition for chemical oxidation occurred using solutions with pH 6 and 7 and reaction times of 30 and 60 minutes.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Seedlings of 41 different citrus species and varieties were massively colonized with the citrus brown aphid Toxoptera citricidus, obtained from Pêra sweet orange (Citrus sinensis) trees, presenting symptoms of the "Capão Bonito" complex of the Citrus tristeza virus (CTV). The objective was to evaluate resistance or tolerance of the varieties to that virus complex, but even after eight months of inoculation no stem pitting was observed in the plants. Otherwise, the presence of galls similar to those induced by the vein enation-woody gall disease was observed in 73% of the plants of Volkamer Palermo (Citrus volkameriana), 60% of the Volkamer Catania 2, 2% of the Rangpur Lime D.22.30 (Citrus limonia), 13% of the Volkamer Australian Red, the Rangpur Lime hybrid, the Orlando tangelo (Citrus reticulata x Citrus paradisi) and the Florida Rough lemon (C. jambhiri), and 7% of the Carrizo citrange (Poncirus trifoliata x Citrus sinensis). The highest incidence and the largest gall size were observed in the Palermo Volkamer showing that this clone would be the most suitable to be used as an indicator plant in biological indexing tests for the disease. There are no previous reports in the literature about the occurrence of woody galls in Orlando tangelo and Carrizo citrange.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Diplomityön tavoitteena oli tutkia biokaasulaitoksen rejektivesien ominaisuuksiin vaikuttavia tekijöitä ja rejektiveden esikäsittelyn tarpeellisuutta. Lisäksi tavoitteena oli tarkastella Kouvolaan suunnitteilla olevan Kymen Bioenergia Oy:n biokaasulaitoksen rejektivesien vaikutusta Kouvolan Veden Mäkikylän jätevedenpuhdistamolla. Biokaasulaitoksen rejektivedet ovat yhdyskuntajätevesiin verrattuna selvästi konsentroituneempia. Jätevedenpuhdistamoilla erityisesti rejektiveden korkea typpipitoisuus aiheuttaa lisäkuormitusta. Suomessa toiminnassa oleville biokaasulaitoksille tehdyn kyselytutkimuksen tulosten perusteella rejektiveden typpipitoisuuteen vaikuttaa syötteen typpipitoisuus sekä mädätysjäännöksen kuivauksen tehokkuus. Rejektiveden kiintoainepitoisuudella on puolestaan vaikutusta biologiseen hapenkulutukseen ja välillisesti myös rejektiveden kemialliseen hapenkulutukseen. Rejektivesien jätevedenpuhdistamoilla aiheuttamaa kuormitusta on mahdollista vähentää esikäsittelemällä rejektivedet joko biologisella tai fysikaalis-kemiallisella puhdistusmenetelmällä. Kyselytutkimus kuitenkin osoitti, että rejektivesien esikäsittelyssä ei aina päästä puhdistustavoitteeseen. Jätevedenkäsittelyn sijaan rejektivesiä on mahdollista käyttää lannoitteena, mikäli biokaasulaitoksen syöte ei sisällä jätevedenpuhdistamon lietteitä. Myös Kouvolan Veden Mäkikylän puhdistamolla biokaasulaitoksen rejektivedet tulevat lisäämään merkittävästi tulovirtaaman typpikuormaa. Typpikuorman lisäys edellyttää ilmastusaltaassa ilmastuksen tehostamista sekä kalkin syöttömäärän lisäämistä, jotta jäteveden happipitoisuus ja pH pysyvät typenpoistoreaktioille suotuisina. Lisäksi tulovirtaamasta puolet tullaan ohjaamaan esiselkeyttimen ohi, jotta ilmastusaltaassa on orgaanista ainetta typenpoistoon riittävästi. Mäkikylän puhdistamon typenpoistokapasiteettia on mahdollista kasvattaa lisähiilen syötöllä. Mikäli biokaasulaitoksen kapasiteettilisäyksen jälkeen rejektivesien typpikuoma ylittää lisähiilellä saavutetun lisäkapasiteetin, on rejektivedet esikäsiteltävä.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Citrus tristeza virus (CTV) isolates from 35 grapefruit accessions belonging to Citrus Active Germplasm Bank of the "Instituto Agronômico de Campinas" located at the "Centro APTA Citros Sylvio Moreira", Cordeirópolis, São Paulo state, Brazil, were characterized and evaluated through symptoms in the trees, biological indexing, immunological diagnosis with different monoclonal antibodies and SSCP analysis (single-strand conformation polymorphism) of the coat protein gene. Symptomatology indicated that, in general, the group of plants with smaller canopy volume and severe stem pitting differed significantly from the group that presented greater vegetative development and mild to moderate stem pitting. However, the isolates from most of the accessions induced mild reaction on Mexican lime. The serological evaluation through the DAS-ELISA using monoclonal antibodies did not reveal any association between virus titer in the plant tissue and symptoms. The reaction with different monoclonal antibodies and the distinct electrophoresis patterns obtained through SSCP showed that there is a high degree of diversity among the isolates that infect these grapefruit accessions. High complexity within the same isolate was also observed in the SSCP profiles. This finding indicates that the CTV isolates from these plants are a complex mixture of CTV haplotypes. Similar SSCP banding patterns were observed among some plants with strong stem pitting symptoms, and among some plants with weak or moderate stem pitting symptoms.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The use of fertilizers and solid amendments in agriculture generates special interest for their effect on crop productivity, as well as for their environmental impact. The efficient use of these products demands knowing their physical and mechanical properties, the storing conditions effect and the operational characteristics of the metering systems used in the fertilizing equipment. In this context, the present study was developed with the purpose of evaluating the operational characteristics of different fertilizing metering systems and to determine the adequate metering system-product operational parameters, using powder lime, powder gypsum, granular 10-30-10 (N-P-K), and granular urea. Operational differences were established among four types of commercial fertilizer metering systems, including wire auger, star-shaped feed wheel, feed screw and ridged traction wheel. The study found that the unloading rate depends directly on the fertilizer metering system's rotating speed and is affected by particle size, repose angle, bulk density and moisture content of the applied product. The wire auger and star-shaped feed wheel metering systems were adequate for the distribution of powder products and the feed screw for granulated fertilizers. Furthermore, theoretical and experimental characteristic equations were established, defining curves for calibration and handling of the products plus the rotating speed range in which a better distributing behavior was achieved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Plug dynamics of non compensate drip tubes were evaluated, by the precipitation of moisturized whitewash [Ca(OH)2], which is used in the fertigation for the bulb pH control of the trademarks Azud, Amanco, Naandan, Netafim, Petroisa, Queen Gil, with flow rate varying between 0.4 to 3.0 L h-1 usually used in the country. For this matter, increasing doses of Ca(OH)² were applied in the irrigation water, from 0.01 g L-1 to 1.84 g L-1. The flow rate of each drip tube was measured in intervals of time initially of 7 days, later of 15 days of system operation, totaling a time of 100 days of operation, corresponding to nine applications or 432 hours. The coefficient of variation (CV), and relative rate flow (Qr) were evaluated. The results pointed differences among the evaluated emitter regarding the occurrence of the clogging, and the models G2 and G5 presented the smallest levels of flow rate variation comparing to the models G6, G7 and G9.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This thesis includes detailed sedimentological and ichnological studies on two geological units: the Pebas Formation, with a special focus in its informal upper member, and the Nauta Formation. Both formations were deposited during the Miocene in Northeastern Peruvian Amazonia, in the Amazon retroarc foreland basin. The Pebas and Nauta successions mainly consist of non-consolidated, clastic sedimentary deposits arranged into sand- to mud-dominated heterolithic successions, which can be upward-coarsening to upward-fining. Sediments in both the Pebas and Nauta successions range from mud to fine- to medium-grained sand. The main facies observed were 1) mud-dominated horizontal heterolithic couplets; 2) rooted brownish mud; 3) lenticular, mud-draped, cross-stratified sand; 4) mud- to sand-dominated, inclined heterolithic stratification; 5) sand-dominated horizontal heterolithic couplets; and 6) mud-draped, trough cross-stratified sand. Locally, tidal rhythmites were documented. The facies are interpreted as: 1) muddy, shallow, subaqueous flats/shoals; 2) palaeosols; 3) secondary tidal channels or run-off creeks; 4) tidally influenced point bars; 5) shoreface deposits; and 6) subtidal compound dunes. Thalassinoides-dominated Glossifungites ichnofacies, low-diversity expressions of the Skolithos ichnofacies and depauperate suites consisting of elements common to the Cruziana ichnofacies strongly indicate brackish-water conditions. However, continental trace fossil assemblages, with possible elements common to the Scoyenia ichnofacies, have also been identified. In addition to the palaeoenvironmental study, a local hydrogeochemical characterisation of the Pebas and Nauta formations was also conducted. The geochemistry of the groundwaters reflects the characteristics and the soil geochemistry of the geological formations studied. The Pebas formation has low hardness, acid to neutral waters, whereas the upper Pebas has high hardness, acid to neutral waters. In both units, the arsenic content is locally high. The Nauta formation has low hardness acid groundwaters. A regional review of the Pebas and Nauta formations placed the local observations into a continental perspective and suggests that the whole Pebas-Nauta system was a probably shallow (some tens of metres at maximum), brackish- to freshwater, tidally-influenced epicontinental embayment with a probable semi-diurnal to mixed tidal regime and a microtidal range, surrounded by continental environments such as forest floors, lagoons, rivers and their flood plains, and lakes.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Kinosternon scorpioides (Linnaeus, 1766), with its common name of jurará, is a quite variable species of turtles, and many different names have been applied to populations throughout its range. Currently, however, four subspecies are considered valid as K. scorpioides arises from southern Panama over most of northern South America and is found in Ecuador, northern Peru, southern Bolivia, northern Argentina, eastern Guyana and Brazil. Thus, an ultrasonographic and radiographic study was performed in order to describe the morphology and development of eggs of 20 female jurará mud turtles K. scorpioides, from September 2005 to August 2006. In the first month, the ovarian cycle was characterized by absence of vitellogenic follicles, atresic follicles or oviduct eggs. From October 2005 to March 2006 on, ultrasonographic scanning allowed to establish the growing vitellogenic follicles. Vitellogenic follicles were observed with spherical to ovoid shapes, with a surrounding echogenic yolk, a nonechogenic albumin layer, and a high echogenic shell. The oviduct eggs were identified by radiography just 180 days after beginning the experiment, when the shell became enough mineralized to impress the radiographic film. This experiment allowed to obtain by means of the 7.5 MHz linear probe images with adequate resolution and penetration for visualization of follicles. Successive ultrasonographic examinations of 20 K. scorpioides females allowed to access initial stages of vitellogenic follicles and oviduct eggs, and radiographic examination revealed to be an easy technique to assess oviduct eggs and to allow evaluation of egg development in jurarás, from 6 months on.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The swear turtle "jurará" (Kinosternon scorpioides) is a mud turtle of the Amazon region exposed to disordering capture in the rural areas of Maranhão, Brazil. Despite its popularity in these areas, little meaningful information regarding the reproductive morphology is currently available, fact that impedes the adoption of policies for preservation of the species. To obtain more information, we studied the ovarian morphology adult jurará females kept in captivity by morphological and morphometric analysis in the dry and rainy season. The results revealed that all females were sexually mature and were in a vitellogenic period. The ovaries are two irregular structures composed by follicles in different stages of development (primary, secondary and tertiary) scattered in a stroma of loose connective highly vascularized tissue. The ovary weight was 6.25±4.23g and 2.27±1.42g, for the right and left one respectively. The gonadosomatic indexes were 2.06% for the dry season and 1.79% for the rainy season. The average of the follicles was 29.83 units per ovary. Microscopically, the mature ovaries revealed a basal layer composed by four cellular layers: the inner and outer theca, stratum granulosum with perivitelline membrane and zona radiata with vitelline membrane. No significant differences were observed in the ovaries either in the dry or wet period.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Ammonia can be used as a pH controller in chloride-based metal recovery processes. In chloride conditions, ammonia reacts to ammonium chloride which can be regenerated back to ammonia with lime. Although the regeneration process itself has been known for a long time, the concentrations, non-reacting species, conditions, and even goals are different when comparing the ammonia regeneration process in different industries. The main objective of this thesis was to study the phenomena, equipment, and challenges in ammonia regeneration in the nickel process and to make a preliminary process design. The study concentrated on the regeneration and recovery units. The thesis was made by process simulation and laboratory tests using the current processes as initial information. The results were combined from all of the information obtained during the studies to provide a total process solution, which can be used as a basis when designing an ammonia regeneration process to be used in industry. In particular, it was possible to determine ammonia recovery with a stripping column and the achievement of the desired ammonia water product within the scope of this thesis. The required mass flows and process conditions were also determined. The possible challenges and solutions or further studies to overcome them were provided as well to ease the prediction and design of the ammonia regeneration process in the future. On the basis of the results of this thesis, the ammonia regeneration process can be developed further and implemented in the nickel chloride leaching process.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This thesis presents a one-dimensional, semi-empirical dynamic model for the simulation and analysis of a calcium looping process for post-combustion CO2 capture. Reduction of greenhouse emissions from fossil fuel power production requires rapid actions including the development of efficient carbon capture and sequestration technologies. The development of new carbon capture technologies can be expedited by using modelling tools. Techno-economical evaluation of new capture processes can be done quickly and cost-effectively with computational models before building expensive pilot plants. Post-combustion calcium looping is a developing carbon capture process which utilizes fluidized bed technology with lime as a sorbent. The main objective of this work was to analyse the technological feasibility of the calcium looping process at different scales with a computational model. A one-dimensional dynamic model was applied to the calcium looping process, simulating the behaviour of the interconnected circulating fluidized bed reactors. The model incorporates fundamental mass and energy balance solvers to semi-empirical models describing solid behaviour in a circulating fluidized bed and chemical reactions occurring in the calcium loop. In addition, fluidized bed combustion, heat transfer and core-wall layer effects were modelled. The calcium looping model framework was successfully applied to a 30 kWth laboratory scale and a pilot scale unit 1.7 MWth and used to design a conceptual 250 MWth industrial scale unit. Valuable information was gathered from the behaviour of a small scale laboratory device. In addition, the interconnected behaviour of pilot plant reactors and the effect of solid fluidization on the thermal and carbon dioxide balances of the system were analysed. The scale-up study provided practical information on the thermal design of an industrial sized unit, selection of particle size and operability in different load scenarios.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Lignocellulosic biomasses (e.g., wood and straws) are a potential renewable source for the production of a wide variety of chemicals that could be used to replace those currently produced by petrochemical industry. This would lead to lower greenhouse gas emissions and waste amounts, and to economical savings. There are many possible pathways available for the manufacturing of chemicals from lignocellulosic biomasses. One option is to hydrolyze the cellulose and hemicelluloses of these biomasses into monosaccharides using concentrated sulfuric acid as catalyst. This process is an efficient method for producing monosaccharides which are valuable platforn chemicals. Also other valuable products are formed in the hydrolysis. Unfortunately, the concentrated acid hydrolysis has been deemed unfeasible mainly due to high chemical consumption resulting from the need to remove sulfuric acid from the obtained hydrolysates prior to the downstream processing of the monosaccharides. Traditionally, this has been done by neutralization with lime. This, however, results in high chemical consumption. In addition, the by-products formed in the hydrolysis are not removed and may, thus, hinder the monosaccharide processing. In order to improve the feasibility of the concentrated acid hydrolysis, the chemical consumption should be decreased by recycling of sulfuric acid without neutralization. Furthermore, the monosaccharides and the other products formed in the hydrolysis should be recovered selectively for efficient downstream processing. The selective recovery of the hydrolysis by-products would have additional economical benefits on the process due to their high value. In this work, the use of chromatographic fractionation for the recycling of sulfuric acid and the selective recovery of the main components from the hydrolysates formed in the concentrated acid hydrolysis was investigated. Chromatographic fractionation based on the electrolyte exclusion with gel type strong acid cation exchange resins in acid (H+) form as a stationary phase was studied. A systematic experimental and model-based study regarding the separation task at hand was conducted. The phenomena affecting the separation were determined and their effects elucidated. Mathematical models that take accurately into account these phenomena were derived and used in the simulation of the fractionation process. The main components of the concentrated acid hydrolysates (sulfuric acid, monosaccharides, and acetic acid) were included into this model. Performance of the fractionation process was investigated experimentally and by simulations. Use of different process options was also studied. Sulfuric acid was found to have a significant co-operative effect on the sorption of the other components. This brings about interesting and beneficial effects in the column operations. It is especially beneficial for the separation of sulfuric acid and the monosaccharides. Two different approaches for the modelling of the sorption equilibria were investigated in this work: a simple empirical approach and a thermodynamically consistent approach (the Adsorbed Solution theory). Accurate modelling of the phenomena observed in this work was found to be possible using the simple empirical models. The use of the Adsorbed Solution theory is complicated by the nature of the theory and the complexity of the studied system. In addition to the sorption models, a dynamic column model that takes into account the volume changes of the gel type resins as changing resin bed porosity was also derived. Using the chromatography, all the main components of the hydrolysates can be recovered selectively, and the sulfuric acid consumption of the hydrolysis process can be lowered considerably. Investigation of the performance of the chromatographic fractionation showed that the highest separation efficiency in this separation task is obtained with a gel type resin with a high crosslinking degree (8 wt. %); especially when the hydrolysates contain high amounts of acetic acid. In addition, the concentrated acid hydrolysis should be done with as low sulfuric acid concentration as possible to obtain good separation performance. The column loading and flow rate also have large effects on the performance. In this work, it was demonstrated that when recycling of the fractions obtained in the chromatographic fractionation are recycled to preceding unit operations these unit operations should included in the performance evaluation of the fractionation. When this was done, the separation performance and the feasibility of the concentrated acid hydrolysis process were found to improve considerably. Use of multi-column chromatographic fractionation processes, the Japan Organo process and the Multi-Column Recycling Chromatography process, was also investigated. In the studied case, neither of these processes could compete with the single-column batch process in the productivity. However, due to internal recycling steps, the Multi-Column Recycling Chromatography was found to be superior to the batch process when the product yield and the eluent consumption were taken into account.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Eutrophication caused by anthropogenic nutrient pollution has become one of the most severe threats to water bodies. Nutrients enter water bodies from atmospheric precipitation, industrial and domestic wastewaters and surface runoff from agricultural and forest areas. As point pollution has been significantly reduced in developed countries in recent decades, agricultural non-point sources have been increasingly identified as the largest source of nutrient loading in water bodies. In this study, Lake Säkylän Pyhäjärvi and its catchment are studied as an example of a long-term, voluntary-based, co-operative model of lake and catchment management. Lake Pyhäjärvi is located in the centre of an intensive agricultural area in southwestern Finland. More than 20 professional fishermen operate in the lake area, and the lake is used as a drinking water source and for various recreational activities. Lake Pyhäjärvi is a good example of a large and shallow lake that suffers from eutrophication and is subject to measures to improve this undesired state under changing conditions. Climate change is one of the most important challenges faced by Lake Pyhäjärvi and other water bodies. The results show that climatic variation affects the amounts of runoff and nutrient loading and their timing during the year. The findings from the study area concerning warm winters and their influences on nutrient loading are in accordance with the IPCC scenarios of future climate change. In addition to nutrient reduction measures, the restoration of food chains (biomanipulation) is a key method in water quality management. The food-web structure in Lake Pyhäjärvi has, however, become disturbed due to mild winters, short ice cover and low fish catch. Ice cover that enables winter seining is extremely important to the water quality and ecosystem of Lake Pyhäjärvi, as the vendace stock is one of the key factors affecting the food web and the state of the lake. New methods for the reduction of nutrient loading and the treatment of runoff waters from agriculture, such as sand filters, were tested in field conditions. The results confirm that the filter technique is an applicable method for nutrient reduction, but further development is needed. The ability of sand filters to absorb nutrients can be improved with nutrient binding compounds, such as lime. Long-term hydrological, chemical and biological research and monitoring data on Lake Pyhäjärvi and its catchment provide a basis for water protection measures and improve our understanding of the complicated physical, chemical and biological interactions between the terrestrial and aquatic realms. In addition to measurements carried out in field conditions, Lake Pyhäjärvi and its catchment were studied using various modelling methods. In the calibration and validation of models, long-term and wide-ranging time series data proved to be valuable. Collaboration between researchers, modellers and local water managers further improves the reliability and usefulness of models. Lake Pyhäjärvi and its catchment can also be regarded as a good research laboratory from the point of view of the Baltic Sea. The main problem in both of them is eutrophication caused by excess nutrients, and nutrient loading has to be reduced – especially from agriculture. Mitigation measures are also similar in both cases.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Meesauunia käytetään sellun tuotantoprosessissa kemiallisessa reaktiossa, jossa kalsiumkarbonaatti muutetaan kalsiumoksidiksi. Reaktio on osa sellutehtaan kemikaalikiertoa, missä sellun valmistamisessa käytettävät kemikaalit kierrätetään uusiokäyttöön. Tässä diplomityössä on kehitetty meesauunin kannatusten automatisoitu suunnittelutyökalu vanhan AutoLispillä kehitetyn ohjelman perusteella. Kehitetyn suunnittelutyökalun tärkeimmät osat ovat Excelissä tehdyt kuormituslaskenta ja mitoituslaskenta. Näillä ohjataan Autodeskin Inventoriin kehitettyä cad-mallia ja valmistuspiirustusta. Laskentaohjelmat ja cad-malli on kehitetty mahdollistamaan uusien uunikokojen helpon lisäämisen ohjelmaan. Diplomityössä on perehdytty kuormituslaskentaan standardien mukaisesti. Käytettyjä standardeja ovat esimerkiksi Eurokoodi ja Uniform Building Code. Epätavallisten tilanteiden kuormituslaskennassa käytettiin apuna FE-analyysilla kehitettyjä laskentamalleja. Näitä käytettiin uunin taipumisesta aiheutuvien voimien laskennassa ja lovetun kannatinpyörän aiheuttamien impulssivoimien suuruuden määrittämisessä. Lisäksi diplomityössä perehdyttiin suunnitteluautomaatin kehittämiseen Exceliä apuna käyttäen. Suunnittelutyökalun toimivuutta on verifioitu suunnittelemalla kehitetyllä suunnittelutyökalulla standardiuuneja ja verrattu tuloksia ja valmistuspiirustuksia vanhalla ohjelmalla tulostettuihin tuloksiin. Tulosten perusteella uutta suunnittelutyökalua voidaan käyttää meesauunin kannatuksien suunnitteluun.