Carla Cristina Almeida Loures

Heterogeneous Photocatalytic Degradation of Dairy Wastewater Using Immobilized ZnO

This work evaluated the efficiency and systemic application of heterogeneous photocatalytic degradation for dairy wastewater under advanced oxidation process (AOP) utilizing solar radiation and immobilized ZnO as measured by total organic carbon (TOC). The AOP system consisted of a semibatch reactor and glass tank operated with an initial volume of 3 L of dairy wastewater. ZnO was immobilized on a metal plate of 800×250 mm and used as a catalyst bed. Evaporation rate was considered when effective degradation of the photocatalytic system was determined. The AOP utilized Taguchi’s L8 orthogonal array. The entry variables were pH, reaction time, initial organic load in the effluent, and ZnO coating thickness on the catalyst bed. When optimized, an effective TOC degradation of 14.23% was obtained under variable values of pH 8.0, a metal-plate coating of 100 micrometers (μm) ZnO, and total reaction time of 180 min.

Evaluation of the cultivation conditions of marine microalgae Chlorella sp. to be used as feedstock in ultrasound-assisted ethanolysis

A total of 8 assays was conducted to study the influence of different variables namely, light intensity, CO2 level, NaNO3 concentration and aeration rate, on the cultivation of the marine microalgae Chlorella sp. to enhance the biomass feedstock availability for biodiesel. The experiments were designed using a Taguchi L8 experimental array set at two levels of operation, having light intensity (0.85 and 14.5 klux), CO2 (5 and 10%), NaNO3 (0.025 and 0.075 g L-1) and aeration rate (3:33 and 1.67 vvm) as independent variables and considering biomass productivity and lipid content as response variables. All the experiments were performed in six photobioreactor vessels connected in series with a total volume of 8.4 L and working volumes of 2 L and 4 L, depending on the conditions assessed. The highest biomass productivity was 210.9 mg L-1day-1, corresponding to a lipid content of 8.2%. Such results were attained when the culture conditions were set at 0.85 klux light intensity, 5% CO2 and 0.075 g L-1 NaNO3. The aeration rate showed no significant influence on the biomass productivity. On the other hand, the highest lipid content was achieved when the cultures were grown using the lowest concentration of NaNO3 (0.025 g L-1) and an aeration rate of 1.67 vvm, while the other factors had no statistical significance. Under these conditions, the lipid content obtained was 19.8%, at the expense of reducing the biomass productivity to 85.9 mg L-1day-1.The fatty acid profile of the lipid material characterized by gas chromatography identified fourteen fatty acids with carbon chain ranging from C8 to C20 in which most of the fatty acids present were saturated (58.7 %) and monounsaturated (36.1%) fatty acids. Those obtained at higher proportions were the oleic (22.8%), palmitic (20.7%) and lauric (17.7 %) acids, indicating a suitable composition for fatty acid ethyl esters (FAEE) synthesis. This was confirmed by acid catalysis performed under ultrasound irradiations reaching a conversion rate of 78.4% within only 4 h.

The Application of Response Surface Methodology in the Study of Photodegraded Industrial Dairy Effluents by the Photo-Fenton Process: Optimization and Economic Viability

This study presents results from an application of Photo-Fenton process for organic-load reduction in dairy effluents. Process efficiency was evaluated in terms of percentage dissolved organic carbon, chemical oxygen demand, and biochemical oxygen demand (DOC, COD, and BOD, resp.), whose initial values were  mg O2 L−1,  mg O2 L−1, and  mg O2 L−1, respectively. We applied a statistical design represented by Box-Behnken factorial design inclusive of Fentons reagent, the power of applied radiation (W), and pH factors. The set temperature value was 30°C with a reaction time of 60 min. The maximum efficiency obtained was at , Fenton reagent in the proportion of 35 g H2O2  3.6 g Fe2

Multivariate Modeling in Quality Control of Viscosity in Fuel: An Application in Oil Industry

Out of specification values can decrease the fuel volatilization, thus implying, in an incomplete combustion (Pontes et al., 2010). This physicochemical property can vary significantly with the modification of the cast during the processing of crude in a refinery (Figure 1), maintaining the same conditions of production control, which compromises the quality standards. This leads to the need to determine the viscosity or provide it as often as possible in lieu of performing the traditional point analysis in the laboratory that can take long time.

Chemometric Methods for the Optimization of the Advanced Oxidation Processes for the Treatment of Drinking and Wastewater

Advanced Oxidative Processes (AOP) have been successfully employed as efficient water treatment methods. The utilization of AOP on drinking and wastewater represents currently an alternative to costly, hazardous, and slow processes. In order to further establish the ground basis for AOP in water safety and security, reliable and consistent methods of analysis are required. As an alternative to basic statistical methods, which may not successfully describe and forecast the application of a given treatment methodology of water, the use of chemometrics has increased significantly over the past decades. Chemometric analyses are an intersection between analytical chemistry and applied statistical models in order to predict and extract information from a given condition. This chapter introduces the concepts of chemometrics in environmental engineering issues and the utilization of experimental design to efficiently analyze experimental data in environmental samples. Two case studies are presented to demonstrate the importance of chemometrics in water analyses: (1) considering a Taguchi L16 experimental design, and an optimization study using Response Surface Methodology, to evaluate photo-Fenton and ozone AOP-based treatment on an effluent with high concentration of organic matter; (2) using a Taguchi L9 array to evaluate the combination of photocatalytic degradation and AOP of an industrial effluent. The results showed in this chapter demonstrate how a given statistical method can be successfully employed within the intersection of environmental analyses and water issues.

Microalgae Assisted Bioremediation of Landfill Leachate Using a Biocoil Reactor: Evaluation of Operational Conditions Using Taguchi Experimental Design

The utilization of organic matter present in low-value effluents, such as landfill leachate, for cultivation of microorganisms exhibit an opportunity for low-cost cell growth while reducing the pollutants in the residue. The feasibility of reducing the organic load and toxic leachate through microalgal cultivation, using Chlorella sp., was investigated using a biocoil reactor. Operating conditions, as temperature, residence time, and illumination cycle were evaluated as control factors, and the responses in reduction of organic matter, turbidity, and metals present in the leachate were assessed. Statistical experimental design and analysis were performed using a Taguchi L4 array, and results show removal rates of TOC in 60%, COD in 68%, turbidity and boron contents in 98%, and a complete removal of iron.

DETERMINAÇÃO DOS PARÂMETROS REOLÓGICOS DA SUSPENSÃO DA MICROALGA CHLORELLA SP

RESUMO A producao de combustiveis renovaveis obteve um grande impulso nos ultimos anos, com o aumento do preco dos combustiveis e as crescentes preocupacoes com questoes ambientais. Dentre as diversas materias primas disponiveis na producao de biocombustiveis, as microalgas surgem como uma alternativa sustentavel devido a elevada produtividade e a falta de necessidade de solos produtivos e agua com qualidade. Levando em conta o interesse crescente na utilizacao das microalgas como materia prima na producao do biodiesel, o objetivo do presente trabalho foi determinar os parâmetros reologicos de suspensoes da microalga Chlorella sp em diferentes tempos de cultivo, sob seis diferentes condicoes de temperatura, salinidade e niveis de CO2, NO3 e PO4, de modo a, posteriormente, estimar as demandas energeticas de cada etapa. Para cada uma dessas condicoes foram feitos testes em reometro rotacional de cilindros concentricos (Brookfield, LVDV). Os resultados mostraram que a suspensao da microalga Chlorella sp trata-se de um material com caracteristicas dilatantes, visto que o incide de comportamento, em todos os casos, resultou em valores superiores a 1.

Multivariate Analysis in Advanced Oxidation Process

Industrial processes can create a wide variety of chemicals that pollute the air and water, with adverse impacts to ecosystems and humans. These impacts are caused by the polluting compounds that have toxic, carcinogenic, and also mutagenic properties (Busca et al., 2008). The treatment of wastewater containing phenolic compounds can be accomplished using applied principles of chemical oxidation, settling, membrane filtration, osmosis, ion, precipitation, and coagulation among other methods (Lin; Juang, 2009).

The Application of a Surface Response Methodology in the Solar/UV-Induced Degradation of Dairy Wastewater Using Immobilized ZnO as a Semiconductor

An Advanced Oxidation Process (AOPs) was carried out in this study with the use of immobilized ZnO and solar/UV as an energy source to degrade dairy wastewater. The semibatch reactor system consisted of metal plate of 800 × 250 mm and a glass tank. The reaction time was of 3 h for 3 L of dairy wastewater. Experiments were performed based on a surface response methodology in order to optimize the photocatalytic process. Degradation was measured in percentage terms by total organic carbon (TOC). The entry variables were ZnO coating thickness and pH, using three levels of each variable. The optimized results showed a TOC degradation of 31.7%. Optimal parameters were metal-plate coating of 100 μm of ZnO and pH of 8.0. Since solar/UV is a constant and free energy source in most tropical countries, this process tends to suggest an interesting contribution in dairy wastewater treatment, especially as a pretreatment and the optimal conditions to guarantee a better efficiency of the process.