Marine Science, Coastal Dynamics and Management

Submarine outfall systems have been presented as a problem solution for domestic wastewater in coastal cities, due to their design facilities and costs. In this study, the application of a mathematical model to predict the effects of the light intensity, salinity and volumetric ratio variables of the mixture of wastewater and seawater in the Escherichia coli (E. coli) die-off rate on the ocean were evaluated. The relationship between the variables mentioned above was established through the MATLAB software, performing laboratory tests established in a rotatable experimental design. Under each combination of factors, the concentration of E. coli was measured at the start of each experiment and every half hour in a total period of two (2) hours using the membrane filtration method of Standard Methods. The results of the tests were statistically analyzed through a stepwise regression, where the mathematical expression was found that allowed to relate the three (3) factors mentioned with the output variable (E. coli die-off rate). This model serves as a tool to predict E. coli die-off rate of any submarine outfall on the planet.