Aplicação de microemulsões na solubilização de frações pesadas de petróleo

This work presents studies related to the use of microemulsions in the solubilization of heavy crude oil fractions responsible by the formation of deposits. The first stage of the work was addressed to the construction of phases diagrams, with the intention of determining the area within which the microemulsion is formed. The following systems were studied: UNITOL L 90 n-Butanol - Water - Kerosene (system 1); UNITOL L 90 - n-Butanol - Water - Xylene (system 2); UNITOL L 90 n-Butanol - Water - Kerosene/Xylene 10% (system 3); UNITOL L 90 - Sec-Butanol - Water - Xylene (system 4). In parallel experiments of physical adsorption were carried out by the static method, with the intention of simulating natural conditions of reservoirs. Crude oil of the Fazenda Belém field (Rio Grande do Norte), was used as solute, xylene as solvent and the Assu sandstone (Rio Grande do Norte, Brazil) and Botucatu sandstone (Paraná, Brazil) as rock reservoirs. The curves of adsorption presented the S format type, in agreement with the classification proposed by Giles, Smith and Huitson (1974). The solubilization process was accomplished in the batch method, by varying the time of agitation, the microemulsions and the solid/solution ratio. The experiments showed that the microemulsions presented high efficiency in the solubilization of the crude oil adsorbed on the sandstones. System 2 presented an efficiency of 99% for the Assu sandstone and 97% for the Botucatu sandstone

Avaliação do processo oxidativo avançado por permanganato de potássio no tratamento de solos contaminados com idrocarbonetos poliaromáticos

The soil contamination with petroleum is one of the major concern of industries operating in the field and also of environmental agencies. The petroleum consists mainly of alkanes and aromatic hydrocarbons. The most common examples of hydrocarbons polyaromatic are: naphthalene, anthracene, phenanthrene, benzopyrene and their various isomers. These substances cause adverse effects on human and the environment. Thus, the main objective of this work is to study the advanced oxidation process using the oxidant potassium permanganate (KMnO4) for remediation of soils contaminated with two polyaromatic hydrocarbons (PAHs): anthracene and phenanthrene. This study was conducted at bench scale, where the first stage was at batch experiment, using the variables: the time and oxidant dosage in the soil. The second stage was the remediation conducted in continous by a fix column, to this stage, the only variable was remediation time. The concentration of oxidant in this stage was based on the best result obtained in the tests at batch, 2,464 mg / L. The results of degradation these contaminants were satisfactory, at the following dosages and time: (a) 5g of oxidant per kg soil for 48 hours, it was obtained residual contaminants 28 mg phenanthrene and 1.25 mg anthracene per kg of soil and (b) for 7g of oxidant per kg soil in 48 hours remaining 24 mg phenanthrene and anthracene 0.77 mg per kg soil, and therefore below the intervention limit residential and industrial proposed by the State Company of Environmental Sao Paulo (CETESB)

Avaliação da capacidade de adsorção do CO2 em zeólita 12X com gases sintéticos e originados da pirólise do lodo de esgoto

This work depicts a study of the adsorption of carbon dioxide on zeolite 13X. The activities were divided into four stages: study batch adsorption capacity of the adsorbent with synthetic CO2 (4%), fixed bed dynamic evaluation with the commercial mixture of gases (4% CO2, 1.11% CO, 1 2% H2, 0.233% CH4, 0.1% C3, 0.0233% C4 argon as inert closing balance), fixed bed dynamic modeling and evaluation of the breakthrough curve of CO2 originated from the pyrolysis of sewage sludge. The sewage sludge and the adsorbent were characterized by analysis TG / DTA, SEM, XRF and BET. Adsorption studies were carried out under the following operating conditions: temperature 40 °C (for the pyrolysis of the sludge T = 600 °C), pressures of 0.55 to 5.05 bar (batch process), flow rate of the gaseous mixture between 50 - 72 ml/min and the adsorbent masses of 10, 15 and 20 g (fixed bed process). The time for the adsorption batch was 7 h and on the fixed bed was around 180 min. The results of this study showed that in batch adsorption process step with zeolite 13X is efficient and the mass of adsorbed CO2 increases with the increases pressure, decreases with temperature increases and rises due the increase of activation temperature adsorbent. In the batch process were evaluated the breakthrough curves, which were compared with adsorption isotherms represented by the models of Langmuir, Freündlich and Toth. All models well adjusted to the experimental points, but the Langmuir model was chosen in view of its use in the dynamic model does not have implications for adsorption (indeterminacy and larger number of parameters such as occurred with others) in solving the equation. In the fixed bed dynamic study with the synthetic gas mixture, 20 g of mass adsorbent showed the maximum adsorption percentage 46.7% at 40 °C temperature and 50 mL/min of flow rate. The model was satisfactorily fitted to the three breakthrough curves and the parameters were: axial dispersion coefficient (0.0165 dm2/min), effective diffusivity inside the particle (dm2/min 0.0884) and external transfer coefficient mass (0.45 dm/min). The breakthrough curve for CO2 in the process of pyrolysis of the sludge showed a fast saturation with traces of aerosols presents in the gas phase into the fixed bed under the reaction process

Recuperação e purificação de quitosanases usando adsorção em leito expandido com streamline DEAE com modelagem e simulação usando redes neurais

Expanded Bed Adsorption (EBA) is an integrative process that combines concepts of chromatography and fluidization of solids. The many parameters involved and their synergistic effects complicate the optimization of the process. Fortunately, some mathematical tools have been developed in order to guide the investigation of the EBA system. In this work the application of experimental design, phenomenological modeling and artificial neural networks (ANN) in understanding chitosanases adsorption on ion exchange resin Streamline® DEAE have been investigated. The strain Paenibacillus ehimensis NRRL B-23118 was used for chitosanase production. EBA experiments were carried out using a column of 2.6 cm inner diameter with 30.0 cm in height that was coupled to a peristaltic pump. At the bottom of the column there was a distributor of glass beads having a height of 3.0 cm. Assays for residence time distribution (RTD) revelead a high degree of mixing, however, the Richardson-Zaki coefficients showed that the column was on the threshold of stability. Isotherm models fitted the adsorption equilibrium data in the presence of lyotropic salts. The results of experiment design indicated that the ionic strength and superficial velocity are important to the recovery and purity of chitosanases. The molecular mass of the two chitosanases were approximately 23 kDa and 52 kDa as estimated by SDS-PAGE. The phenomenological modeling was aimed to describe the operations in batch and column chromatography. The simulations were performed in Microsoft Visual Studio. The kinetic rate constant model set to kinetic curves efficiently under conditions of initial enzyme activity 0.232, 0.142 e 0.079 UA/mL. The simulated breakthrough curves showed some differences with experimental data, especially regarding the slope. Sensitivity tests of the model on the surface velocity, axial dispersion and initial concentration showed agreement with the literature. The neural network was constructed in MATLAB and Neural Network Toolbox. The cross-validation was used to improve the ability of generalization. The parameters of ANN were improved to obtain the settings 6-6 (enzyme activity) and 9-6 (total protein), as well as tansig transfer function and Levenberg-Marquardt training algorithm. The neural Carlos Eduardo de Araújo Padilha dezembro/2013 9 networks simulations, including all the steps of cycle, showed good agreement with experimental data, with a correlation coefficient of approximately 0.974. The effects of input variables on profiles of the stages of loading, washing and elution were consistent with the literature

Alteração de atributos físicos em latossolo com aplicação superficial de escória de aciaria, lama cal, lodos de esgoto e calcário

Os resíduos industriais e urbanos podem atuar como condicionadores do solo, pois possuem a capacidade de alterar suas propriedades físicas. Contudo, não há referência para os atributos físicos do solo quando esses resíduos são aplicados sobre a superfície do solo no sistema plantio direto. O objetivo deste trabalho foi avaliar o efeito da aplicação superficial de escória de aciaria, lama cal, lodos de esgoto e calcário nos atributos físicos de um Latossolo Vermelho distrófico sob sistema plantio direto. Os tratamentos foram constituídos por quatro resíduos: lodos de esgoto centrifugado - LC e de biodigestor - LB, escória de aciaria - E, e lama cal - Lcal, interagindo com quatro doses (0, 2, 4 e 8 t ha-1, aplicadas na forma seca) mais uma testemunha (controle), constituída da aplicação de 2 t ha-1 de calcário. O delineamento experimental foi em blocos casualizados no esquema fatorial 4 x 4 + 1, com quatro repetições. A presença de Ca na composição de lama cal, lodo de esgoto centrifugado, escória de aciaria e calcário permite o aumento da agregação das partículas, diâmetro médio ponderado, índice de estabilidade de agregados, porosidade e retenção de água, sendo essas alterações distintas para cada fonte, dose e profundidade de reação no solo. A aplicação superficial da lama cal na dose de 8 t ha-1, após 27 meses de reação, proporcionou a maior agregação das partículas no solo, desde a superfície até 40 cm de profundidade.

Disponibilidade de metais pesados em Latossolo com aplicação superficial de escória, lama cal, lodos de esgoto e calcário

O objetivo deste trabalho foi avaliar alguns atributos químicos do solo e a disponibilidade de cádmio (Cd), cromo (Cr), níquel (Ni), mercúrio (Hg), chumbo (Pb) e arsênio (As), por meio da extração pelo DTPA, em conseqüência da aplicação superficial de escória de aciaria, lama cal e lodos de esgoto centrifugados e de biodigestores, nas doses 0 (testemunha), 2, 4 e 8 Mg ha-1 e um tratamento adicional composto pela calagem superficial na dose 2 Mg ha-1. O experimento foi conduzido em delineamento de blocos ao acaso, em condições de campo, em área sob sistema plantio direto, durante 2003 e 2004. A aplicação superficial de escória de aciaria, lama cal, lodo de esgoto centrifugado e de biodigestor, até a dose 8 Mg ha-1, assim como o calcário na dose 2 Mg ha-1, não trazem problemas de disponibilidade ao ambiente, com relação aos metais pesados Cd, Cr, Hg, Pb, Ni e As, quando aplicados sobre a superfície em Latossolo Vermelho distrófico, no sistema plantio direto. A fitodisponibilidade de metais pesados às culturas da soja e aveia-preta foi nula, quando foram aplicadas doses de até 8 Mg ha-1 de lodo de esgoto, escória e lama cal sobre a superfície do solo, no sistema plantio direto.

Correção da acidez e mobilidade de íons em Latossolo com aplicação superficial de escória, lama cal, lodos de esgoto e calcário

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aplicação superficial de escória, lama cal, lodos de esgoto e calcário na cultura da soja

O objetivo deste trabalho foi avaliar o efeito da aplicação superficial de lodos de esgoto, lama cal, escória de aciaria e calcário sobre o estado nutricional e a produtividade da soja, em sistema plantio direto. O delineamento foi o de blocos ao acaso em arranjo fatorial 4x4+1, constituído por quatro tratamentos - resíduos de lodo de esgoto centrifugado (LC) e de biodigestor (LB), escória de aciaria (E) e lama cal (Lcal) - nas doses 0, 2, 4 e 8 Mg ha-1, mais o controle com 2 Mg ha-1 de calcário. As plantas de soja apresentaram maior concentração de nitrogênio, fósforo e cálcio, em 2003, 2004 e 2005, e de potássio, em 2003 e 2004, em razão dos tratamentos LC, LB, E, Lcal e calagem. A produtividade da soja foi favorecida pela aplicação dos tratamentos no sistema plantio direto, em 2003, 2004 e 2005. O fósforo, e o cálcio contribuíram para o aumento da produtividade da soja em 2003 e 2004.

Microemulsões aplicadas ao tratamento de Óleos isolantes

Naphthenic lubricating oils are used in transformers with the purpose of promoting electrical insulation and dissipating heat. The working temperature range of these oils typically lies between 60°C and 90°C and their useful life is 40 years in average. In that temperature range, the oils are decomposed during operation, whereby a small fraction of polar compounds are formed. The presence of these compounds may induce failure and loss of physical, chemical and electrical properties of the oil, thus impairing the transformer operation. By removing these contaminants, one allows the oxidized insulating oil to be reused without damaging the equipment. In view of this, an investigation on the use of surfactants and microemulsions as extracting agents, and modified diatomite as adsorbent, has been proprosed in this work aiming to remove polar substances detected in oxidized transformer oils. The extraction was carried out by a simple-contact technique at room temperature. The system under examination was stirred for about 10 minutes, after which it was allowed to settle at 25°C until complete phase separation. In another experimental approach, adsorption equilibrium data were obtained by using a batch system operating at temperatures of 60, 80 and 100°C. Analytical techniques involving determination of the Total Acidity Number (TAN) and infrared spectrophotometry have been employed when monitoring the decomposition and recovery processes of the oils. The acquired results indicated that the microemulsion extraction system comprising Triton® X114 as surfactant proved to be more effective in removing polar compounds, with a decrease in TAN index from 0.19 to 0.01 mg KOH/g, which is consistent with the limits established for new transformer oils (maximal TAN = 0.03 mg KOH/g). In the adsorption studies, the best adsorption capacity values were as high as 0.1606 meq.g/g during conventional adsoprtion procedures using natural bauxite, and as high as 0.016 meq.g/g for the system diatomite/Tensiofix® 8426. Comparatively in this case, a negative effect could be observed on the adsorption phenomenon due to microemulsion impregnation on the surface of the diatomite

Avaliação de catalisadores a base de carbeto e nitreto de molibdênio na obtenção de lactitol via hidrogenação da lactose

Seeking a greater appreciation of cheese whey was developed to process the hydrogenation of lactose for the production of lactitol, a polyol with high added value, using the catalyst Ni / activated carbon (15% and 20% nickel), the nitride Mo2N, the bimetallic carbide Ni-Mo/ activated carbon and carbide Mo2C. After synthesis, the prepared catalysts were analyzed by MEV, XRD, laser granulometry and B.E.T. The reactor used in catalytic hydrogenation of lactose was the type of bed mud with a pressure (68 atm), temperature (120 oC) and stirring speed (500 rpm) remained constant during the experiments. The system operated in batch mode for the solid and liquid and semi-continuous to gas. Besides the nature of the catalyst, we studied the influence of pH of reaction medium for Mo2C carbide as well as evaluating the character of the protein inhibitor and chloride ions on the activity of catalysts Ni (20%)/Activated Carbon and bimetallic carbide Ni-Mo/Activated Carbon. The decrease in protein levels was performed by coagulation with chitosan and adsorption of chloride ions was performed by ion exchange resins. In the process of protein adsorption and chloride ions, the maximum percentage extracted was about 74% and 79% respectively. The micrographs of the powders of Mo2C and Mo2N presented in the form of homogeneous clusters, whereas for the catalysts supported on activated carbon, microporous structure proved impregnated with small particles indicating the presence of metal. The results showed high conversion of lactose to lactitol 90% for the catalyst Ni (20%)/Activated Carbon at pH 6 and 46% for the carbide Mo2C pH 8 (after addition of NH4OH) using the commercial lactose. Monitoring the evolution of the constituents present in the reaction medium was made by liquid chromatography. A kinetic model of heterogeneous Langmuir Hinshelwood type was developed which showed that the estimated constants based catalysts promoted carbide and nitride with a certain speed the adsorption, desorption and production of lactitol

Produção de bioetanol a partir de pedúnculo de caju (Anacardium occidentale L.) por fermentação submersa

Recently, global demand for ethanol fuel has expanded very rapidly, and this should further increase in the near future, almost all ethanol fuel is produced by fermentation of sucrose or glucose in Brazil and produced by corn in the USA, but these raw materials will not be enough to satisfy international demand. The aim of this work was studied the ethanol production from cashew apple juice. A commercial strain of Saccharomyces cerevisiae was used for the production of ethanol by fermentation of cashew apple juice. Growth kinetics and ethanol productivity were calculated for batch fermentation with different initial sugar (glucose + fructose) concentration (from 24.4 to 103.1 g.L-1). Maximal ethanol, cell and glycerol concentrations (44.4 g.L-1, 17.17 g.L-1, 6.4 g.L-1, respectively) were obtained when 103.1 g.L-1 of initial sugar concentration were used, respectively. Ethanol yield (YP/S) was calculated as 0.49 g (g glucose + fructose)-1. Pretreatment of cashew apple bagasse (CAB) with dilute sulfuric acid was investigated and evaluated some factors such as sulfuric acid concentration, solid concentration and time of pretreatment at 121°C. The maximum glucose yield (162.9 mg/gCAB) was obtained by the hydrolysis with H2SO4 0.6 mol.L-1 at 121°C for 15 min. Hydrolysate, containing 16 ± 2.0 g.L-1 of glucose, was used as fermentation medium for ethanol production by S. cerevisiae and obtained a ethanol concentration of 10.0 g.L-1 after 4 with a yield and productivity of 0.48 g (g glucose)-1 and 1.43 g.L-1.h-1, respectively. The enzymatic hydrolysis of cashew apple bagasse treated with diluted acid (CAB-H) and alkali (CAB-OH) was studied and to evaluate its fermentation to ethanol using S. cerevisiae. Glucose conversion of 82 ± 2 mg per g CAB-H and 730 ± 20 mg per g CAB-OH was obtained when was used 2% (w/v) of solid and loading enzymatic of 30 FPU/g bagasse at 45 °C. Ethanol concentration and productivity was achieved of 20.0 ± 0.2 g.L-1 and 3.33 g.L-1.h-1, respectively when using CAB-OH hydrolyzate (initial glucose concentration of 52.4 g.L-1). For CAB-H hydrolyzate (initial glucose concentration of 17.4 g.L-1), ethanol concentration and productivity was 8.2 ± 0.1 g.L-1 and 2.7 g.L-1.h-1, respectively. Hydrolyzates fermentation resulted in an ethanol yield of 0.38 g/g glucose and 0.47 g/g glucose, with pretreated CABOH and CAB-H, respectively. The potential of cashew apple bagasse as a source of sugars for ethanol production by Kluyveromyces marxianus CE025 was evaluated too in this work. First, the yeast CE025 was preliminary cultivated in a synthetic medium containing glucose and xylose. Results showed that it was able to produce ethanol and xylitol at pH 4.5. Next, cashew apple bagasse hydrolysate (CABH) was prepared by a diluted sulfuric acid pre-treatment. The fermentation of CABH was conducted at pH 4.5 in a batch-reactor, and only ethanol was produced by K. marxianus CE025. The influence of the temperature in the kinetic parameters was evaluated and best results of ethanol production (12.36 ± 0.06 g.L-1) was achieved at 30 ºC, which is also the optimum temperature for the formation of biomass and the ethanol with a volumetric production rate of 0.25 ± 0.01 g.L-1.h-1 and an ethanol yield of 0.42 ± 0.01 g/g glucose. The results of this study point out the potential of the cashew apple bagasse hydrolysate as a new source of sugars to produce ethanol by S. cerevisiae and K. marxianus CE025. With these results, conclude that the use of cashew apple juice and cashew apple bagasse as substrate for ethanol production will bring economic benefits to the process, because it is a low cost substrate and also solve a disposal problem, adding value to the chain and cashew nut production

Recuperação e purificação de ramnolipídeos produzidos por pseudomonas aeruginosa P029-GVIIA utilizando melaço de cana como substrato

Biosurfactants are molecules produced by microorganisms mainly bacteria as Pseudomonas and Bacillus. Among the biosurfactants, rhamnolipids play an important role due to their tensoactive as well as emulsifying properties. Besides can be produced in a well consolidated way the production costs of biosurfactants are quite expansive mainly if downstream processing is goning to be considered. Actually, attention has been given to identification of biosurfactants as well as optimization of its fermentative processes including downstream ones. This work deals with the development of strategies to recovery and purification of rhamnolipids produced by Pseudomonas aeruginosa P029-GVIIA using sugar-cane molasses as substrate. Broth free of cells was used in order to investigate the best strategies to recovery and purification produced by this system. Between the studied acids (HCl and H2SO4) for the acid precipitation step, HCl was the best one as has been showed by the experimental design 24. Extraction has been carried out using petroleum ether and quantification has been done using the thioglycolic acid method. Adsorption studies were carried out with activated carbon in a batch mode using a 24 experimental design as well as combined with an hydrophobic resin Streamline Phenyl aiming to separate the produced biosurfactant. Biosurfactant partial identification was carried out using High Performance Liquid Chromatography (HPLC). Experiments in batch mode showed that adsorption has been controlled mainly by pH and temperature. It was observed a reduction of 41.4% for the liquid phase and the solid phase it was possible to adsorb up to 15 mg of rhamnolipd/g of activated carbon. The kinetics of adsorption has been well fitted to a pseudo-first order reaction with velocity constant (k1) of 1.93 x 10-2 min-1. Experiments in packed bed ranging concentration on eluent (acetone) has been shown the highest recovery factor of 98% when pure acetone has been used. The combined effect if using activated carbon with an hydrophobic resin Streamline Phenyl has been shown successful for the rhamnolipids purification. It has been possible to purify a fraction of the crude broth with 98% of purity when the eluted of activated carbon packed bed was used with pure acetone

Estudo da remoção de Ba2+, Ni2+, Cd2+, Cu3+, Cr3+, Sr2+, Zn2+ por eletrocoagulação em água associada à produção de petróleo

Among the waste generated in the petrochemical industry water associated with oil production is the most important. It is considered one of the great challenges due to the presence of considered toxic chemicals present in this composition. The presence of these substances difficult to reuse the water associated with the enhanced recovery processes, so that prior to their reuse or disposal, treatment is necessary. This paper aimed to study the removal efficiency of chemical species: Ba2+, Ni2+, Cd2+, Cu2+, Cr3+, Sr2+ and Zn2+, present in the composition of the water associated with oil production by electrocoagulation. The evaluation of removal of these chemical species was performed by laboratory tests using electrochemical batch reactors and continuous flow. Initial tests were performed with electrocoagulation of synthetic wastewater in batch reactor using iron electrode. Results of removal of Zn2+ and Ni2+ were 78 % and 59 % respectively. While the percentage of removed Ba2+ was 19 % by 30 minutes of treatment and by applying current of 1.10 A. The tests were performed on effluent batch reactor applying the electrochemical technique with stainless steel electrodes 304, the objective was to remove part of the dispersed oil and also of organic compounds in the effluent. Under the experimental conditions used, the maximum result was obtained TOG was 60 % and TOC was approximately 50 % compared to the initial concentration. In the experiments carried out in continuous reactor, with effluent semisynthetic, have been used electrodes of iron and aluminum and the results were 100 % removal of Cd2+, Cu2+, Cr3+ and Zn2+ and 77 % of Sr2+. These percentages were only attainable through the use of the iron electrode. However, when the electrode was replaced by aluminum, there was a reduction in the percentage of removal to 65 %, using the same flow rate and current. Therefore according to the results obtained using the iron electrode was more effective in removing these metals and the conditions of lower current and lower flow rate was satisfactory, as observed in the experimental design adopted

Tratamento de água de produção de petróleo visando o aproveitamento na obtenção de barrilha

The petroleum production is associated to the produced water, which has dispersed and dissolved materials that damage not only the environment, but also the petroleum processing units. This study aims at the treatment of produced water focusing mainly on the removal of metals and oil and using this treated water as raw material for the production of sodium carbonate. Initially, it was addressed the removal of the following divalent metals: calcium, magnesium, barium, zinc, copper, iron, and cadmium. For this purpose, surfactants derived from vegetable oils, such as coconut oil, soybean oil, and sunflower oil, were used. The investigation showed that there is a stoichiometric relationship between the metals removed from the produced water and the surfactants used in the process of metals removal. It was also developed a model that correlates the hydrolysis constant of saponified coconut oil with the metal distribution between the resulting stages of the proposed process, flocs and aqueous phases, and relating the results with the pH of the medium. The correlation coefficient obtained was 0.963. Next, the process of producing washing soda (prefiro soda ahs ou sodium carbonate) started. The resulting water from the various treatment approaches from petroleum production water was used. During this stage of the research, it was observed that the surfactant assisted in the produced water treatment, by removing some metals and the dispersed oil entirety. The yield of sodium carbonate production was approximately 80%, and its purity was around 95%. It was also assessed, in the production of sodium carbonate, the influence of the type of reactor, using a continuous reactor and a batch reactor. These tests showed that the process with continuous reactor was not as efficient as the batch process. In general, it can be concluded that the production of sodium carbonate from water of oil production is a feasible process, rendering an effluent that causes a great environmental impact a raw material with large scale industrial use

Recuperação de fósforo por cristalização de estruvita

This study investigated the influence of the molar ratio, the phosphorus initial concentration, the mixture gradient, mixing time, pH and the secondary nucleation on struvite s crystallization in synthetic water in batch reactors. The study was divided into two stages. The first investigated struvite s crystallization at different Mg:N:P molar ratios and at different initial concentrations of magnesium, nitrogen and phosphorus. It was also evaluated the importance of secondary nucleation on the struvite s crystallization. In the second, five parameters were tested to evaluate their influence on the struvite s crystallization, which were: Mg:N:P molar ratio, initial concentration of phosphate, mixing time, mixture gradient and pH. The best conditions for struvite s crystallization were: Mg:N:P = 1,3:1:1 molar ratio; mixture gradient = 60 rpm, pH = 10.0, mixing time = 5 minutes and high initial concentrations of the constituent ions of struvite. Furthermore, the use of struvite crystals as seed influenced positively on the struvite s crystallization