Miria Hespanhol Miranda Reis

Effects of coconut granular activated carbon pretreatment on membrane filtration in a gravitational driven process to improve drinking water quality

This study evaluates the performance of a polymeric microfiltration membrane, as well as its combination with a coconut granular activated carbon (GAC) pretreatment, in a gravitational filtration module, to improve the quality of water destined to human consumption. The proposed membrane and adsorbent were thoroughly characterized using instrumental techniques, such as contact angle, Brunauer–Emmett–Teller) and Fourier transform infrared spectroscopy analyses. The applied processes (membrane and GAC + membrane) were evaluated regarding permeate flux, fouling percentage, pH and removal of Escherichia coli, colour, turbidity and free chlorine. The obtained results for filtrations with and without GAC pretreatment were similar in terms of water quality. GAC pretreatment ensured higher chlorine removals, as well as higher initial permeate fluxes. This system, applying GAC as a pretreatment and a gravitational driven membrane filtration, could be considered as an alternative point-of-use treatment for water destined for human consumption.

Ultrasound-assisted extraction of bioactive compounds from green tea leaves and clarification with natural coagulants (chitosan and Moringa oleífera seeds)

In this study, a sequential process of extraction and clarification by natural coagulants and centrifugation successfully produced green tea extracts clear and enriched in bioactive compounds. Desirability function methodology was applied to optimize ultrasound-assisted extraction (UAE) of total polyphenols and flavonoids by the evaluation of the parameters temperature (22-83 °C), tea-to-water ratio (12-73 g  L-1) and amplitude (23-77%). Green tea clarification was carried out using the extract at UAE optimized conditions (77, 73 g L-1, 77%). The effect of centrifugation and the concentrations of chitosan (25-2000 mg L-1) and Moringa oleífera seeds (MOS) (100-10000 mg L-1) were evaluated. The best clarification conditions were at the concentrations of chitosan 500 mg L-1 and MOS 8000 mg L-1 followed by centrifugation. These optimized clarification conditions provided turbidity, solids and polyphenols reduction of 95% and 96%, 16 and 16%, 18 and 19% for chitosan and MOS treatments, respectively. The main individual compounds identified by high liquid chromatography (HPLC) were epigallocatechin gallate, epicatechin, epigallocatechin and catechin, gallic acid and caffeine.

Influência do pré-tratamento na microfiltração de polpa de cajá-manga (Spondias dulcis)

Neste trabalho foi avaliado o uso da microfiltracao (MF) da polpa de caja-manga com e sem pre-tratamento. As frutas foram selecionadas, higienizadas e trituradas com agua na proporcao de 1:3 (m/m). Primeiramente, por meio de um planejamento de experimentos foi otimizada a extracao visando obter maior concentracao de compostos fenolicos (CF). Para MF utilizou-se membrane plana de ester de celulose de 0,8 µm (Milipore) em Sistema batelada com area de filtracao de 0,00636 m² sem e com aplicacao da etapa de pre-tratamento (centrifugacao), avaliou-se CF pelometodo de Folin–Ciocalteu, solidostotais, brix, cor e turbidez. Os dados foram analisados por ANOVA e teste de Tukey (p<0,05). Em relacao a otimizacao a temperatura foi significativa, sendo que as melhores extracoes ocorreram em tempo de 30 min e temperatura 75 0C. O pre-tratamento nao apresentou influencia para os valores de turbidez, cor, solidos, compostos fenolicos e brix dos permeados obtidos. Analisando o fluxo de permeado pode-se afirmar que o pre-tratamento utilizado neste caso, ou seja, a centrifugacao, foi eficiente para minimizar o entupimento da membrana. Assim, conclui-se que o processo de microfiltracao com anterior centrifugacao apresenta potencial para ser aplicado no processamento de polpa de caja-manga.

Evaluation of the Removal of Chlorine, THM and Natural Organic Matter from Drinking Water Using Microfiltration Membranes and Activated Carbon in a Gravitational System

Beyond off-flavors development due to chlorination by-products, chlorine flavor by itself constitutes one of the major complaints against tap water. In 1996, chlorine taste was the third most reported taste default of tap water in the US (Suffet et al., 1996). Due to the unpleasant taste of tap water, consumers may prefer bottled water as drinking water, even if bottled drinking water consumption would be associated with a higher economic and ecological cost. (Rodriguez et al., 2004) showed that the perception of tap water quality is closely related to the residual chlorine level: people living near a treatment plant who may receive a higher chlorine level in their tap water were generally less satisfied by tap water quality and perceived more risks associated with it than people living far from the plant. It was reported that, in the US, bottled water drinkers have three main categories for decisions: safety of water; healthfulness of the water; and taste of the water (Mackey et al., 2004). Consumers supplied with tap water containing a residual chlorine level greater than 0.24 mg/L Cl2 were less satisfied with tap water when compared to consumers receiving lower concentrations (Rodriguez et al., 2004). This value almost coincides with the free chlorine residual (0.2 mg/L) that must be maintained in the distribution system, reducing the likehood of further contamination (Clark & Coyle, 1990). When taken together, this studies underline that the consumers would reject tap water in safe conditions due the chlorine flavor.