Alexandre Lioi Nascentes

Avaliação do efeito do extrato de sementes de Moringa oleifera Lam na eficiência de filtros orgânicos no tratamento de águas residuárias de bovinocultura de leite

Objetivou-se avaliar o efeito do extrato de Moringa oleifera Lam na remocao de solidos totais (ST), solidos em suspensao totais (SST) e demanda quimica de oxigenio (DQO), em distintos meios filtrantes, no tratamento da agua residuaria de bovinocultura de leite (ARB). O extrato de sementes de moringa foi obtido triturando-se 50 g de sementes em um litro de agua destilada e, apos passar a solucao em papel de filtro quantitativo de 25 µm, foram adicionados 60 mL do extrato a agua residuaria de bovinocultura, antes do processo de filtracao em filtros orgânicos constituidos por fino de carvao, folhas de bambu, folhas de eucalipto, ramos de gliricidia e serragem de madeira. Seguiu-se o delineamento experimental inteiramente aleatorizado, adotando um esquema fatorial de 5 x 2. Aliquotas do efluente filtrado foram coletadas, e determinaram-se as concentracoes de solidos totais (ST), solidos em suspensao totais (SST) e demanda quimica de oxigenio (DQO). Verificou-se que o aumento na eficiencia de remocao de solidos totais e DQO pode ser atribuido ao poder coagulante do extrato de sementes de moringa, sendo que o meio filtrante com folhas de bambu apresentou melhor desempenho, demonstrando potencial de utilizacao como material filtrante alternativo no tratamento primario de ARB.

Mathematical modeling of COD removal via the combined treatment of domestic wastewater and landfill leachate based on the PACT process

The experiments performed in this study consisted of 16 batch reactors fed different mixtures of landfill leachate combined with synthetic wastewater treated using the Powdered Activated Carbon Treatment (PACT) process. The objective was to measure the COD mass removal per liter each day for each reactor using two models: the first model combined the variables PAC concentration (0 g·L−1, 2 g·L−1, 4 g·L−1, and 6 g·L−1) and leachate rate in the wastewater (0%, 2%, 5%, and 10%), and the second model combined the PAC concentration and the influent COD. The Response Surface Methodology with Central Composite Design was used to describe the response surface of both models considered in this study. Domestic wastewater was produced under controlled conditions in the laboratory where the experiments were performed. The results indicated that the PAC effect was null when the influent did not contain leachate; however, as the concentration of leachate applied to the mixture was increased, the addition of a higher PAC concentration resulted in a better COD mass removal in the reactors. The adjusted R2 values of the two models were greater than 0.95, and the predicted R2 values were greater than 0.93. The models may be useful for wastewater treatment companies to calculate PAC requirements in order to meet COD mass removal objectives in combined treatment.