Filtração em cerâmica microporosa aplicada à remoção de cor e turbidez de água para abastecimento público

Um filtro cerâmico com porosidade de 0,1μm, 60 cm de altura e 6 cm de diâmetro e 1 cm de espessura foi utilizado para estudar a remoção de cor e turbidez da água bruta. A unidade apresentava 0,113m² de superfície externa e estava montada no interior de uma coluna em acrílico com 100 cm de altura e 23 cm de diâmetro, com volume útil de 41,5 L. A água bruta, utilizada na pesquisa, foi proveniente de uma represa onde os valores de turbidez variaram de 2,3 a 2,8 NTU e cor aparente de 93 e 109 PtCo. Foram empregadas 3 diferentes taxas de aplicação, sendo de 1,82, 3,16 e 4,49m3/m2.dia, onde foram realizadas três carreiras de filtração para cada taxa. A duração de cada carreira de filtração estabilizou em 100, 42 e 26 minutos, respectivamente para cada taxa de aplicação. As amostras de água, utilizadas para verificar sua qualidade, foram coletadas, na entrada e saída do filtro a cada 5 cm de perda de carga até completar 20 cm. Os resultados obtidos demonstraram uma eficiência na remoção de turbidez entre 75 e 80%, resultando valores de entre 0,53 e 0,58 NTU para a última carreira de filtração para cada taxa de aplicação. Em contrapartida o sistema não se mostrou eficiente para remoção de cor aparente ficando entre 27 e 38%, mantendo valores elevados, ou seja, superiores a 62 PtCo, dessa forma o sistema não se mostrou eficiente para a remoção de cor

Reuse of alum sludge for reducing flocculant addition in water treatment plants

The recycling of water treatment residues (WTR) inside drinking water treatment plants (DWTP) to be a good option for reusing this type of waste, as well as for reducing the costs with its disposal off and with the acquisition of treatment chemicals. Therefore, a WTR was reused for auxiliary of the coagulation-flocculation processes for reducing the use of aluminium sulfate (coagulant) in a DWTP. Three series of experiments have been conducted involving three water samples with different turbidity and colour, different WTR samples with different total suspended solids (TSS) concentrations and different aluminium sulfate concentrations. The results showed that WTR can efficiently be used for the removal of turbidity between 21 NTU and 218 NTU and colour between 194 HU and 1509 HU for TSS concentration between 1635 mg/dm3 and 5420 mg/dm3, with better results in the range between 1635 mg/dm3 and 2678 mg/dm3. For higher TSS concentrations, the removal of both parameters decrease because there are excess of organics released to water, which demands the use of more coagulant

Activated carbon produced from waste coffee grounds for an effective removal of bisphenol-A in aqueous medium

Abstract Bisphenol-A is widely used chemical in industry and unfortunately often detected in natural waters. Considered as an emerging pollutant, bisphenol-A represents an environmental problem due to its endocrine-disrupting behavior. The production of activated carbon from alternative precursors has shown to be attractive in the removal of emerging pollutants from the water. Activated carbon was produced from waste coffee by physical and chemical activation and applied in the removal of bisphenol-A. The samples were characterized by elemental analysis, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and analysis of textural properties. Bisphenol-A adsorption experiments showed that the chemically activated carbon was more efficient due to its high specific surface area (1039 m2/g) compared to the physically activated carbon (4.0 m2/g). The bisphenol-A adsorption data followed the pseudo-second-order model and Langmuir isotherm, which indicated a maximum adsorption capacity of 123.22 mg/g for chemically activated carbon. The results demonstrated a potential use of the coffee grounds as a sustainable raw material for the production of chemically activated carbon that could be used in water treatment