Estratégias de minimização de efluentes na síntese e integração de processos

No presente estudo avaliou-se a possibilidade de métodos de optimização na resolução de problemas de minimização de águas potáveis e efluentes. Utilizaram-se para o efeito diferentes ferramentas de optimização (EXCEL, LINGO 7.0, funções de optimização do MATLAB 7.0), na avaliação de dois casos de estudo: i) Remoção de fenol em efluentes aquosos de uma instalação de reciclagem de óleo, como exemplo de um problema de linearidade da função objectivo e suas restrições; ii) Minimização de água e efluentes aquosos numa refinaria de petróleo, como exemplo de um problema de não linearidade da função objectivo e suas restrições. Mostra-se que problemas de prevenção e controlo da poluição podem ser, de um modo eficaz, avaliados por optimização matemática

Factores condicionantes da dádiva benévola de sangue em estudantes universitários em Luanda

A proporção de colheitas de dadores voluntários pode ser usada como indicador não só do potencial de disponibilidade de sangue mas também da sua segurança. Em Luanda, Angola, a dádiva voluntária correspondeu a cerca de 23% das dádivas em 2004. Foi realizado um estudo observacional descritivo transversal pela aplicação de um questionário constituído por itens que captam factores que motivam ou inibem a dádiva benévola de sangue, numa amostra de estudantes universitários em Luanda. Apesar da baixa dádiva voluntária indicada pelos respondentes, verificou-se uma elevada disponibilidade para a dádiva benévola, essencial no combate ao HIV.The proportion of voluntary blood donors can be used as an indicator not only of the potential availability of blood supplies but also its safety. In Luanda, Angola, the voluntary donation was about 23% of all donations in 2004. We conducted a cross-sectional observational study through questionnaire application which captured factors that motivate or inhibit the benevolent blood donation, among a sample of university students in Luanda. Despite the low voluntary donation indicated by respondents there was a high availability for the voluntary donation, essential in fighting HIV

Characterization of bubbles in a bubble column by image analysis

Fundação para a Ciência e a Tecnologia (FCT); EC

Intracellular poly-P assessment by DAPI staining and image analysis

In wastewater treatment, enhanced biological phosphorus removal (EBPR) is considered a well-established process to remove phosphate (P). EBPR is based on the activity of polyphosphate-accumulating organisms (PAOs) able to take up and store large amounts of P as intracellular (poly-P) granules. However, monitoring poly-P in mixed cultures is usually performed by a laborious and time consuming off-line chemical analysis. Thus, there is a clear need to develop new techniques to rapidly monitor these processes, such as image analysis coupled to sample staining and microscopy inspection. A lab-scale sequencing batch reactor (SBR) was fed with synthetic wastewater containing acetate and propionate as main carbon sources and an orthophosphate solution was added. A COD/P ratio of 10 mg COD mg P-PO4-1 was used to provide selective advantages to PAOs. The SBR was operated with a cycle time of 6 h: 120 min anaerobic including 5 min feed, 180 min aerobic and 60 min wasting/settling. Biomass samples were collected at the end of the aerobic stage. Bulk P concentration was determined by segmented flow analysis and total P concentration was similarly measured following acid digestion at 100oC. Intracellular poly-P concentration was determined by subtracting the bulk P from the total P. Intracellular poly-P granules were observed in epifluorescence microscopy using DAPI staining with a 25 ìg mL-1 DAPI solution. A long pass filter was used with an excitation bandpass of 365-370 nm and emission cut off at 421 nm. A specially developed program in Matlab was used for image analysis. A total of 41 samples were collected. Two thirds were fed as training data to the partial least squares (PLS) model and the remaining used for validation. Both absolute (in mg poly-P / L) and relative (in mg poly-P / g MLSS) intracellular poly-P concentrations were studied. This procedure was found to predict, at some extent, the relative intracellular poly-P concentration (real poly-P = 0.971 x predicted poly-P, R2 of 0.744). Regarding the absolute intracellular poly-P concentration, a total of 3 samples needed to be discarded in order to obtain a similar result (real poly-P = 1.005 x predicted poly-P, R2 of 0.731)

Hormonal induction of Atlantic dusky grouper (Epinephelus marginatus) broodstock

Immature fish and young females were sex reversed using hormonal induction in two consecutive years. In the first year one permanent male was obtained. Collected sperm of both years ranges from 30 μl to 300 μl and cell concentration varies from 3 to 6.5 x109 spermatozoa/ml. Atlantic dusky grouper can successfully be induced to functional males with 17α-methyltestosterone implants

Biological process optimal design in a wastewater treatment plant

The aim of this paper is to determine the optimal design and operation of an activated sludge system that is being installed in a small town in the north of Portugal. This process design takes into consideration real data in order to define the objective cost function which includes both investment and operation costs. The collected data were also used to characterize the wastewater in that region. To define the constraints of the optimization problem, we consider very well established models for the aeration tank and the secondary settler, together with the system balances and some system definitions. The highly nonlinear optimization problem was solved through the internet by the SNOPT solver provided by the NEOS Server. We found, for the minimum cost, the optimal design/operation for the above mentioned system in terms of the volume of the aeration tank, air flow needed for the biological sludge, the sedimentation area and the secondary settler depth, to name a few of the involved variables

Polylactic Acid/Carbon Nanoparticle Composite Filaments for Sensing

Polylactic acid (PLA) is a bio-based, biodegradable polymer that presents high potential for biomedical and sensing applications. Ongoing works reported in the literature concern mainly applications based on 3D printing, while textile applications are hindered by the limited flexibility of PLA and its composite filaments. In the present work, PLA/multiwall carbon nanotube (MWCNT) composite filaments were produced with enhanced flexibility and electrical conductivity, which may be applied on a textile structure. A biodegradable plasticizer was incorporated in the nanocomposites, aiming at improving MWCNT dispersion and increasing the flexibility of the filaments. Filaments were produced with a range of compositions and their morphology was characterized as well as their thermal, thermomechanical, and electrical properties. Selected compositions were tested for sensing activity using saturated acetone vapor, demonstrating a suitable response and potential for the application in fabrics with sensing capacity

Contribution of a simple sludge treatment in a WWTP optimization procedure

In the sequence of the work done with a combined ATV and double exponential model to describe the secondary settler concerning the optimal design of a wastewater treatment plant (WWTP), a simple sludge treatment based on dewatering followed by deposition in landfills is now included in the system. Power consumption, transport and deposition of the sludge are involved in the operation cost of the sludge treatment. This work aims to evaluate the contribution of this cost in the WWTP design total cost. The experiments carried out with three WWTPs in design show that the considered wasted biosolids treatment does not affect the design although is responsible for 10 to 14% of the total costs

Polyphosphates and poly-β-hydroxybutyrate granules identification through quantitative image analysis in enhanced biological phosphorus removal systems

Enhanced biological phosphorus removal (EBPR) is a widely implemented technique for having the potential to cheaply and reliably remove phosphate from wastewater treatment processes, than traditional chemical methods. EBPR is performed by operating the system sequentially with anaerobic and aerobic conditions. Several studies were already performed ranging from different strategies for the competition between polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) to modeling both types of bacterial activities. Until now, slight attention has been given to the development of newer, faster, simpler, and better suited monitoring techniques for this type of system. This work is focused on the development of image analysis techniques for polyphosphates and poly-β-hydroxybutyrate granules in EBPR systems since off-line analyses are labor intensive and not able to be performed in full-scale plants. A lab-scale sequencing batch reactor fed with synthetic wastewater containing volatile fatty acids (VFAs) and orthophosphate was used. The reactor had a working volume of 4 L and was operated with a cycle time of 6 h consisting of 2 h anaerobic, 3 h aerobic, 50 min settling and decanting, and 5 min anaerobic idle periods. In each cycle, 2 L of synthetic wastewater was fed to the reactor in the first 5 min of the anaerobic period, resulting in a hydraulic retention time (HRT) of 12 h. The pH was controlled during both the anaerobic and aerobic periods around 7, and the temperature was controlled at 30 ºC in order to provide selective advantages to GAOs over PAOs. The ratio between chemical oxygen demand (COD) and P in the feed was kept at 10 (gCOD/g P). Biomass samples were collected at the end of the anaerobic and aerobic phases and fixed with phosphate buffer saline solution (PBS) and ethanol. Two fluorescence staining methods were used: (1) DAPI for poly-P identification; and (2) nile blue for poly-β-hydroxybutyrate granules. So far, promising results were achieved regarding the type of images achieved by these fluorescence staining methods and the image analysis procedures still under development