Tank truck loading operations in fuel distribution terminals have particular characteristics which are challenging to simulate. Demands for different fuel types are correlated rather than independent. In addition, queuing policies which do not address the current state of the terminal may increase equipment idleness and trucks' lead time. We propose a decomposition of the joint probability distribution of fuel types and a procedure to simulate it. We also propose a new queuing policy aimed at reducing equipment idleness and trucks' lead time. The procedures are tested and validated through a discrete-event simulation model of a real fuel distribution terminal. We simulate alternative scenarios in which we increase fuel flow rate as well as the number of loading arms and test a new queuing policy. Results show the effectiveness of the simulation procedure in replicating real performance indicators. Moreover, the proposed idleness-based queuing policy resulted in lower idleness and lead time compared with a first-come-first-served policy.

ResumoEste trabalho teve como objetivo propor alternativas para a minimização dos impactos ambientais causados pela geração de resíduos sólidos e líquidos a partir da lavagem de caminhões em uma indústria de concreto no município de Santa Maria -RS. Para a análise dos resíduos líquidos foram coletadas amostras nos meses de junho a outubro de 2009, em cinco pontos pré-definidos. Os valores obtidos pelas análises foram comparados com os resultados da amostra testemunha e os valores determinados pela NBR 13.696 (ABNT, 1997). A avaliação destes parâmetros apresentou a real eficiência dos decantadores já instalados na Empresa. Com isto, foi possível verificar a necessidade de se projetar um novo dimensionamento do sistema. O resíduo (lodo) proveniente dos decantadores já implantados na empresa foi removido com uma pá, seco ao ar e em câmara úmida, peneirado e incorporado na argamassa, substituindo-se parte da areia por porcentagens de 10%, 25% e 50%. Os corpos-de-prova foram rompidos aos 7, 14 e 28 dias de cura. O efluente apresentou uma grande disparidade entre a amostra testemunho (poço artesiano) e a amostra no final do sistema de tratamento. Em relação aos resíduos sólidos, a incorporação do lodo gerado na indústria pode significar a redução de um impacto ambiental, contribuindo assim para um desenvolvimento sustentável, onde não será desperdiçado nenhum material gerado. AbstractThis work aimed to propose alternatives to minimize environmental impacts caused by the generation of solid and liquid waste from the truck wash in a concrete industry in the municipality of Santa Maria -RS. For the analysis of wastewater samples were collected from June to October 2009, in five pre-defined points. The values obtained by the analysis were compared with the results of the control sample and the values determined by NBR 13.696 (ABNT, 1997). The evaluation of theses parameters showed the actual efficiency of decanters already installer in the Company. With this, was found the need to design a new system. The residue (sludge) from the decanters already deployed in the enterprise was removed with a shovel, and air dried in a moist chamber incorporated in the mortar and sieved by replacing the sand by percentages of 10%, 25% and 50%. The bodies of the specimens were broken at 7, 14 and 28 days of healing. The effluent showed a large disparity between the control sample (borehole) and the end of the sample treatment system. Regarding solid waste, incorporate the sludge generated in the industry can mean the reduction of environmental impact, thereby contributing to sustainable development, where there will be no wasted material generated.