A new responsibility for the Brazilian water industry in the era of privatization: Dynamic plant management for the treatment of storm and waste combined urban waters

Abstract

In Brazil, sanitary sewage must go to sewers separated from the drainage system. Yet, increasingly common illicit stormwater connections into sewers, allied to the ageing process of both systems, are causing relevant stormwater infiltration into sewers - thus, also into wastewater treatment plants. Consequent plant overloads may induce combined sewer overflows (CSO, onto rivers or public and private areas) and disturb treatment, often yielding effluents of insufficient quality and affecting receiving waters likewise. Environmental impacts like these are quantitatively reported here for urban areas of São Paulo State. Inspired by solutions developed in northern countries where, due to climatic and historical reasons, wastewater traditionally joins the stormwater in combined sewers, regulatory and engineering tools are suggested which may help operate plants, and plan, design, monitor, operate and manage complex wastewater systems. Finally, the role of river water-quality models in assisting dynamic treatment plant operation is envisaged, and quantitatively exemplified.