DESIGN? THE DESIGN OF RECTANGULAR SEPTIC TANKS BY USING THE FOSEP TOOL.

Septic tanks are a low-cost alternative for the treatment of wastewater generated in rural and urban areas. The pollutant removal efficiency of a septic tank depends on the characteristics of the effluent and in particular on the size of the tank. The objective of this work was the development of a software application that calculates the dimensions of a rectangular septic tank for domestic or public service with a maximum volume of 15 000 L. The FOSEP application was built with Visual Basic v. 6.0 programming language for the calculation of the variables length (L), width (A), minor tie-rod (H1), major tie-rod (H2) and total volume (Vt). The FOSEP tool was applied to a case study to evaluate the design and operation of a septic tank that treats domestic wastewater generated by 60 users in the community of ?El Alberto? in the state of Hidalgo. The analysis of the design with the FOSEP tool showed that the septic tank does not comply with the dimensions recommended by this application, but it is efficient in the removal of COD, TSS, SSV and fecal coliforms.