Browsing by Author "Pardal, Ana"
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- ERSAR service quality indicators – practical case of a MunicipalityPublication . Pardal, Ana; Miguel, CatarinaIntroduction: Waste services are fundamental in modern societies as they contribute significantly to the social and economic development of the country. Therefore, they must comply with a set of principles, among which are the universality of access, continuity and quality of service and price efficiency and equity, constituting an important factor of social balance. From the point of view of regulation and evaluation of the quality of public services provided to users, The Water and Waste Services Regulation Authority (ERSAR) plays a leading role. Objectives: To analyze the service quality indicators (SQI) of a medium-sized city council for the period 2011 to 2016, which allow to evaluate in a technical, environmental and economic terms an municipal solid waste management system. Methods: The evaluation of municipal solid waste (MSW) management services is carried out through three groups of quality of service quality indicators (performance indicators): indicators that reflect the protection of user interests; indicators that reflect the sustainability of service management and, finally, indicators that translate environmental sustainability. Results: The results obtained in the service quality indicators for the evaluation of the goals of the Portuguese Strategic Plan for MSW Management (PERSU 2020) show that the city has yet to make an effort to meet the goals defined for the sector by 2020. Conclusions: Overall, the analysis shows that the system presents mainly levels medium and unsatisfactory quality of service.
- Wastewater treatment of biodiesel production using persulphate ion as an oxidantPublication . Borralho, Maria; Pardal, Ana; Coelho, SolangeIntroduction: The production of biodiesel produces a highly polluting effluent, because presents high values of Chemical Oxygen Demand (COD), oils and fats, among other contaminants. Sodium persulphate is a powerful oxidant (Eº = 2.1V). In addition to the direct oxidation that is favored in alkaline media, it can be induced by photolytic processes, catalytic and / or catalytic photos forming sulphate radicals (Eº = 2.6 V) thus providing reaction mechanisms with free radicals like hydroxyl radicals. Methods: In this work the effect of the potassium monopersulphate compound (2KHSO5.KHSO4K2SO4), (Oxone) on the removal of COD in residual water from the biodiesel purification step was tested. Results: The tests, direct oxidation at alkaline pH and catalytic oxidation with cobalt ions, Co(II), showed that the former, for Oxone concentrations of 1.00x10-2 M and 4.00x10-3 M, were not effective because no decomposition occurred, for reaction times over three hours, thus not occurring removal of COD. In the catalytic assays combinations were tested, varying between 5.00x10-3 M and 7.50x10-2 M for the oxidant and 0.10 μM and 1.00 μM for the catalyst. The complete decomposition of the oxidant was always verified between 15 min. and 2 h. The tests with the lowest concentration of cobalt showed COD removal rates around 20% and the highest one reached 60%. Conclusions: The most favorable assay achieves significant COD removals, but not enough for the effluent to be discharged in the hydric medium according the portuguese legislation.