MATHEMATICAL-MODELING OF SULFIDES AND HYDROGEN-SULFIDE GAS BUILDUP INTHE COSTA DO ESTORIL SEWERAGE SYSTEM

The Costa do Estoril sewerage system is one of the largest separate sy stems ever built in Portugal. Because of the quality of the environmen t in the region and the high level of touristic use, special care was given, in its design, to sulphide calculations. This paper describes t he application to the Costa do Estoril sewerage system of an integrate d computer model for forecasting sulphides and hydrogen sulphide gas b uild-up along sewer atmospheres. The empirical sulphide prediction equ ations have been calibrated with experimental results obtained under a research project carried out in a gravity tributary and in a rising m ain located near the Costa do Estoril zone. The hydrogen sulphide gas concentrations along the main trunk line have been predicted according to an mathematical model described by Mates and Sousa. The results of the model have been considered to be adequate for identifying critica l reaches and for predicting the effects of corrective and preventive measures on the overall behaviour of the system.