Modelización del transporte de contaminantes en redes de saneamiento urbano

Resumo

Although the dissolved form of pollutants is generally more toxic and more reactive chemically and biologically, the impact of the particulate form is more significant in the long term because of its accumulation capacity and its capacity to act as a secondary source of dissolved contaminants. For this reason, it has been considered essential to include the dynamics of suspended solids since sediment contamination is considered by several international environmental organisms as the greatest risk in aquatic environments. Consequently, prediction of sediment transport, erosion and deposition is an extremely important task in understanding the characteristics of water quality. However, it should be borne in mind that although the introduction of a greater number of variables in the model allows for a more precise analysis, it also requires a greater amount of information to feed it. The coastal zones bear strong anthropic pressure due mainly to rapid industrialization and population increase, which translates into pollution sources represented by domestic and industrial effluent discharges. This is the case, for example, of the Ria de Huelva in which, in addition to the pressure of industrial and port activity itself, mining spills and the erosion of pyritic terrains acidify the waters further away from the sea by allowing metals are maintained in dissolved form. The main aim of this work is to present a simplified model to predict the sediment transport rate in combined sewer pipe. Particle size distribution and particle density are very significant factors in transport models. It varies in function of the sewer location and pollutant source. A sensitivity analysis of the transport rate and concentration profiles in pipes has been conducted in this study. The model presented results from the integration of two models. On the one hand, the EPA's Wastewater Management Model (SWMM), and on the other, the simplified model to predict the sediment transport rate in combined sewer pipe. This integration complements and enriches the network analysis by solving the EPA's software limitation of not simulating the propagation of contaminants in the subsurface flow, i.e. within the pipelines, once the runoff flow enters the sanitation system. As well as other predictive models allow to obtain information for the analysis of the temporal and spatial distribution of the emissions to the environment, essential tool as support to the decision making to improve the control of the intermittent contamination by discharges of unitary systems. You can also obtain information on load patterns that arrive at a sewage plant or a holding tank at the start of a storm event, allowing for more rational resource planning.