Analysis of scenarios for wastewater and urban drainage systems in Brazil based on an integrated modeling approach.

Brazil is currently facing widespread problems in the urban environment associated with inadequate wastewater and urban drainage systems, particularly for low-income communities. These problems are promoted by the rapid and often unplanned urbanization process in developing cities and are compounded by a lack of funding, absence of planning, ineffective institutional arrangements, and inappropriate policies to provide the framework for integrated wastewater and stormwater management. Because planning for the provision of wastewater and urban drainage systems is a complex task, an integrated-modeling approach is proposed to provide a practical methodology for sanitation and urban drainage planning in Brazilian cities. In the model development, as well as technical aspects, other aspects related to institutional, financial, socio-economic, environmental and public health issues were also taken into account.

Reaction coefficient (K) evaluation for full-scale facultative pond systems.

Facultative ponds have found application in wastewater treatment as an economical system where geographical locations are available at reasonable cost. Several design methods have been reported to describe the organic matter removal of a facultative pond and to determine the reaction coefficient (K) in general terms. Therefore, it is important to evaluate if these coefficient values can be used satisfactorily in regional cases. For this purpose the data of two full-scale facultative ponds located in Brazlandia and Samambaia, in the mid-west region of Brazil, were used. A correlation between applied COD load and reaction coefficient (K) was obtained based on a mathematical adjustment using the dispersed flow hydraulic model. The results provide a suggested regional design parameter for facultative ponds in this region in terms of domestic wastewater.