COMBINED SEWER OVERFLOWS IN BRAZIL: A 2014 SITUATION REPORT

Abstract

Combined sewer systems are common at coldregions, where heavy storms, that disturb wastewatertreatment processes by combined sewer overflows (CSO),are rare. However, in warm countries, the ageing process ofcollection pipes (causing underground leakage of rain waterinto separate sewers) and illicit connections of drainagepipes into sewers (increasingly common, either insidepremises or between public, sewer and drainage systems)cause wastewater treatment plant inflow surges and qualitydisturbances to raw and treated sewage. Such perturbationsbear close similarity to CSO impacts, and cause plants toyield low quality effluents – thus, jeopardizing receivingwaterquality. The article briefly introduces the CSOproblem in the world, first. Then, it reports the currentsituation at some Brazilian cities and towns that are fightingthe problem by legal measures, and campaigns for educatingcitizens and companies such as to reduce illicit connectionsand preserve the integrity of these hydraulic systems.

 

 

Index Terms - Combined sewer overflow, storm effluentcontrol, illicit sewer connection, dynamic plant operation,environmental education.