1. Department of Hydraulic and Environmental Engineering, Federal University of Ceará, Campus do Pici, Bloco 713, Fortaleza, CE, Brazil E-mail: fjas@cariri.ufc.br; rsouza@ufc.br
2. Companhia de Água e Esgoto do Ceará – CAGECE, Av. Dr. Lauro Vieira Chaves, 1030, Fortaleza, CE, 60.420-280. E-mail: castro@cagece.com.br
3. Department of Natural Resources, Technological Education Federal Centre of Rio Grande do Norte. Av. Sen. Salgado Filho, 1559, Tirol, 59000-015, Natal-RN, Brazil. Post-Graduation Program of Sanitary Engineering, Federal University of Rio Grande do Norte. E-mail: acalado@cefetrn.br