Emerson Andrade Sales

Comparative energy life-cycle analyses of microalgal biomass production in open ponds and photobioreactors

An analysis of the energy life-cycle for production of biomass using the oil-rich microalgae Nannochloropsis sp. was performed, which included both raceway ponds, tubular and flat-plate photobioreactors for algal cultivation. The net energy ratio (NER) for each process was calculated. The results showed that the use of horizontal tubular photobioreactors (PBRs) is not economically feasible ([NER]<1) and that the estimated NERs for flat-plate PBRs and raceway ponds is >1. The NER for ponds and flat-plate PBRs could be raised to significantly higher values if the lipid content of the biomass were increased to 60% dw/cwd. Although neither system is currently competitive with petroleum, the threshold oil cost at which this would occur was also estimated.

Palladium catalysts in the selective hydrogenation of hexa-1,5-diene and hexa-1,3-diene in the liquid phase. Effect of tin and silver addition Part 1. Preparation and characterization: from the precursor species to the final phases

Palladium, palladium–tin and palladium–silver catalysts, supported on two alumina samples with different acidity, have been prepared by diffusional impregnation for use in the selective hydrogenation of hexa-1,5-diene and hexa-1,3-diene in the liquid phase. UV–VIS–NIR (transmission and diffuse reflectance) studies of the palladium starting solutions and of the solids obtained during all preparation stages (impregnation, drying, calcination) show that the nature of the supported precursor species depends on the acidity of the alumina. Palladium tetrachloropalladate (strongly bound anionic species) are predominant on the more acidic alumina while the more basic one favours the formation of weakly bound neutral complexes through exchange of chloride ligands with hydroxy groups and water. The nature of these species influences not only the particle size of monometallic Pd samples (the stronger the interaction, the smaller the metal particle size), but also the nature of the final bimetallic Pd–Ag catalysts; a Pd–Ag solid solution is observed on the bimetallic catalyst prepared by interaction of a cationic Ag precursor withsupported PdCl42-, whereas interaction with neutral Pd species leads to separate metal phases. The interaction of Sn precursor solutions with supported PdII species induces the formation of heteronuclear species which decompose upon drying; Pd2Sn or Pd3Sn phases are detected on the final catalysts, depending on the initial Pd/Sn ratio and on the nature of the Sn precursor solvent (using ethanol favours the formation of Pd3Sn).

Mössbauer Study of 119Sn-Pd Catalysts for Selective Hydrogenation of Hexa-1,5-Diene

The addition of tin to palladium-alumina catalysts induces significant modifications of the catalytic properties of palladium in the hydrogenation of hexa-1,5-diene. The influence of the support, of the metal loading and of the preparation method on the chemical state of tin in Pd-Sn/Al2O3 catalysts are studied by Mössbauer spectroscopy. In reduced catalysts, about 60% of tin is present as Sn(0), which forms different Pd-Sn compounds, that are responsible for the changes in the catalytic performances.

Parametric sensitivity analysis for temperature control in outdoor photobioreactors

In this study a critical analysis of input parameters on a model to describe the broth temperature in flat plate photobioreactors throughout the day is carried out in order to assess the effect of these parameters on the model. Using the design of experiment approach, variation of selected parameters was introduced and the influence of each parameter on the broth temperature was evaluated by a parametric sensitivity analysis. The results show that the major influence on the broth temperature is that from the reactor wall and the shading factor, both related to the direct and reflected solar irradiation. Other parameter which play an important role on the temperature is the distance between plates. This study provides information to improve the design and establish the most appropriate operating conditions for the cultivation of microalgae in outdoor systems.

Cultivation of Nannochloropsis sp. in brackish groundwater supplemented with municipal wastewater as a nutrient source

The aim of this work was to study growth potential of the green microalgae Nannochloropsis sp. using brackish groundwater from a well in the semi-arid northeast region of Brazil as culture medium. The medium was supplemented with (%) 19.4, 22.0, 44.0 and 50.0% of municipal wastewater after UASB treatment as a low-cost nutrient source. The results showed that the culture tested was capable of growing in the brackish groundwater even at salinity levels as low as 2 ppt. Furthermore it was shown that municipal wastewater could be used as a sole nutrient source for Nannochloropsis sp.

Water and Wastewater Management in a Petrochemical Raw Material Industry

Abstract Based on cleaner production concepts, a methodology for water use minimization has been developed by the Clean Technology Network of Bahia at one of the largest industrial complex in Latin America, in Camacari, Bahia, Brazil. Here we present the methodological tools and results of the water and wastewater minimization program at a petrochemical plant operated by Braskems Raw Material Unit (UNIB) at this complex. The set of tools used includes reconciled aqueous stream balances, database of aqueous streams, definition and analysis of water and wastewater indicators, as well as regional analysis in a search for more environmentally friendly water sources. Water mass balances had to be built with assumed values as poor measurement or rather lack of water measurement is a constant inside the industrial complex. Because of this, the proposed indicators had to be analyzed with caution. The studies have identified the possibility of recovering about 1,500 m 3 /h of the overall 5,700 m 3 /h water consumed by the industrial complex at the moment. The effluent flow rate has been reduced by 250 m 3 /h since 2002. Process variability was found to be an important cause of both effluent generation in total flow rate and its continuity.

Hollow glass microspheres for temperature and irradiance control in photobioreactors

The addition of hollow glass microspheres (HGM) to polymers to change thermal insulation and mechanical properties is widely used. In this study HGM were tested as a new construction material for photobioreactors to control irradiance and broth temperature in microalgae cultivation. The heat isolation properties of HGMs of three different densities were tested in a polymer matrix. The transmittance (5-50%) and the thermal conductivity (182.05-190.73 W/mK) of the HGM composite material were analyzed. The results were tested in a model to predict the broth temperature and the growth rate as a function of temperature and irradiance. The addition of 1.3 and 0.6 vol.% of HGM lead to an increase in the growth rate of up to 37% and a reduction in the broth temperature up to 9°C. The mechanical resistance of the composites tested is similar to the polymer matrix.