ISEP - Departamento de Engenharia Química
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- Incidence of nitrate, nitrite, chloride and phosphate in groundwater in Modivas, PortugalPublication . Silva, Susana; Sousa, José; Ramalhosa, M. J.; Antão, M. Cristina; de Sá Barroso, Maria de Fátima; Pina, Maria de Fátima; Pina, Maria de Fátima; Delerue-Matos, Cristina; Delerue-Matos, Cristina; Beleza, VitorinoThe aim of this project consisted in the evaluation of chemical quality of groundwater in domestic wells situated in the village of Modivas, which belongs to the district of Porto, in north of Portugal. The population doesn’t have a public water supply system and the groundwater is a significant source for domestic, livestock breeding and agricultural use. The quality of water samples were collected from domestic wells with an approximate deph of 15m and the quality has been investigated with respect to pH, conductivity, temperature, nitrate, nitrite, phosphate and chloride. Geographical coordinates were also measured at each location, using a GPS device. The obtained results show that a strong nitrate contamination exists in the studied area. A very small percentage of wells (2%) were above the guideline for nitrite. As for the other parameters (chloride and phosphate) the results never exceeded the legal limit.
- Introduction of the parameter 'Total Organic Carbon' (TOC) as a standard for the quality control of swimming pool waterPublication . Beleza, Vitorino de Matos; Costa, Rosária Santos; Baptista, Marta Pinto; Beleza, Vitorino; Pereira, IsabelSwimmers introduce organic compounds into swimming pools due to the transferring of sweat, saliva, skin, hair, urine, feces, among other materials, to the water. Water quality control in the tank must include some chemical parameters that will quantitatively reflect the presence of these contaminants in the water. Oxidability to permanganate is included in the regulations and norms of public swimming pools in most developed countries. According to the Portuguese norm NP-731, permanganate oxidability is determined by the oxidation of organic compounds in the water by potassium permanganate in acidic conditions when boiling for 10 minutes. |n fact, this procedure detects all reductants oxidized by the essay conditions, whether organic or inorganic. To overcome these limitations, several entities suggested the determination of Total Organic Carbon (TOC). lsocyanuric acid, H30;C;N;, is used as a stabilising agent for free chlorine. In its combustion, cyanuric acid is totally oxidised, and the products of this reaction are carbon dioxide, which contributes to the TOC value, water and nitrogen. Analytical confirmation of the carbon:isocyanuric acid relationship was performed in the Centro de Estudos de Aguas laboratory, achieving ‘the value of 0.27 quite close to the theoretical relation carbon:isocyanuric acid (0.28). This relationship will help to definition of a maximum value for TOC in swimming pool water, in function of its depth.
- Re-utilization of sewage sludges as a precursor for activated carbon productionPublication . Gutiérrez, Maria S. C.; Rocha, Maria J.; Mendes, Sandra S.; Freitas, Maria Madalena; Silva, Paula; Beleza, VitorinoThe possibility of re-utilization of sewage sludges from wastewater treatment plants as raw-material for activated carbon production was investigated. Activated carbons were prepared from secondary sludges by physical activation with carbon dioxide. Pyrolysis was carried out in nitrogen atmosphere at 873 K during 3 h. Physical activation was performed in pure CO2 flow, for 1h, at temperatures between 1123 and 1223 K. Global yields of the process range from 30 to 4o wt %. Activated carbons have surface areas from 60 to 100 m?/g and micropore volumes up to 0,020 cm3/g. Porous structure presents about 50% microporosity. A chemically activated sample (H.SO,, 973 K, 15 min, N, flow) was also prepared for comparative purposes. Results show that activated carbons produced have potential to be used as pollutant adsorbent, but further optimization studies will be needed in order to improve its porous structure.
- Studies of particulate fouling for a water-kaolin suspension flowing in a horizontal square section channelPublication . Ribeiro, A. M.; Ferreira, V.; Campos, J. B. L. M.; Beleza, VitorinoExperimental particulate fouling studies were carried out for an aqueous suspension of kaolin at a concentration of6 kg/m, flowing at 2.99 x 103 m3/s in a square section horizontal channel and using stainless steel deposition plates. Fouling resistance curves obtained for three positions on the bottom deposition plates showed an initial enhancement of heat transfer, but as the deposition process continued, the fouling resistance increased until it reached a constant value. Measurements of the mass and the thickness of the dry kaolin deposits on the plates at the end of the experiment (144 days) showed that deposition was higher for the bottom plates than for the top ones.
- Sustainability issues in swimming pools and spasPublication . Martins, Florinda; Beleza, Vitorino; Pereira, IsabelThis paper discusses sustainability applied to swimming pools and spas. Sustainability is nowadays a subject that crosses every human activity and health, sport and recreational activities are no exception. Well being is a target of modern society and can not be dissociated from social, environmental and economic aspects.