River Autodepuration Capacity Itabirito, Minas Gerais, Brazil

Raphael Ricardo da Silva, Aníbal da Fonseca Santiago, Heloisa Cristina França Cavallieri Pedrosa, and Wagner

José Melilo da Silva

Basic Sanitation Service of the Municipality of Itabirito, Brazil

Abstract: The Itabirito River is located in the municipality of Itabirito, belonging to the hydrographic network basin of the Velhas river in the central region of the state of Minas Gerais, Brazil. Know the capacity of the main river in the municipality of Itabirito is relevant due to its position in the hierarchy of the fluvial system of the Velhas river basin, constituted as important basin for both the state of Minas Gerais and some Brazilian Northeast. The objective of this work is to evaluate the self-purification process of the River Itabirito, in a stretch of approximately 20 km, considering the upstream and downstream of the launch of the sanitary sewage treatment plant of the municipality. The methodological model used, was the classic of Streeter Phelps, the parameters of dissolved oxygen (DO) and demand biochemistry of oxygen (BOD5). The results obtained from these analyzes were compared with the maximum values allowed by Resolution 357/2005 of the National Environmental Council (NEC), for freshwater class II river, Itabirito river classification according to ND 20/97- Normative deliberation that provides for the framing of waters of the Velhas river basin. The results indicate that the river assimilated the organic load launched by the municipality and that the operations of the sewage treatment station not changes the BOD5 parameter to the Class II framing limitie 5 mg/l.

Key words: dissolved oxygen, BOD 5, River Itabirito, Streeter Phelps, mathematical modeling