Effects of rainwater intrusion on an activated sludge sewer treatment system

  • Diogo Botelho Correa de Oliveira Programa de Pós-Graduação em Engenharia Civil. Universidade de Pernambuco (UPE), Rua Benfica, n° 455, CEP: 50720-001, Recife, PE, Brazil.
  • Willames de Albuquerque Soares Escola Politécnica de Pernambuco. Departamento de Física de Materiais. Universidade de Pernambuco (UPE), Rua Benfica, n° 455, CEP: 50720-001, Recife, PE, Brazil.
  • Marco Aurélio Calixto Ribeiro de Holanda Programa de Pós-Graduação em Engenharia Civil. Escola Politécnica de Pernambuco (POLI-UPE). Universidade de Pernambuco (UPE), Rua Benfica, n° 455, CEP: 50720-001, Recife, PE, Brazil.
Keywords: absolute separator system, activated sludge, effluent treatment

Abstract

 

Effluent collection and stormwater management make use of different drainage systems, which should remain unconnected with one another. If stormwater drains into sewage collection systems, it often causes changes in effluent quality indicators at sewage treatment plants. This study sought to quantify the changes caused by rain in a Wastewater Treatment Plant (WWTP) located in Paulista, PE, which uses the activated sludge system. Accordingly, changes in pH, temperature, BOD, and treatment efficiency at the inlet and outlet, as well as inlet flow were analyzed on dry and rainy days at the plant, which has a sewage capacity of 400 L s-1. The input volume was found to be greater than the design flow of the station, about 25%. With this, some relevant operational controls were identified, such as temporarily shutting down sewage pumping stations in order to maintain full operation of the system and avoid overload. The pH increases slightly in alkalinity, about 0.3, but this does not interfere with the treatment process. The temperature of the influent on rainy days is about 3 to 5 degrees cooler, depending on the intensity of the event. Using the T and Z tests, it was possible to identify that BOD concentrations in the influent and the effluent were not significantly different (uneq. var. t: 1.18 > 0.26 and uneq var. z: 0.71 > 0.48, respectively), and the organic load removal efficiency was maintained, contrary to what is expected with other, more simple types of treatment.


Author Biographies

Diogo Botelho Correa de Oliveira, Programa de Pós-Graduação em Engenharia Civil. Universidade de Pernambuco (UPE), Rua Benfica, n° 455, CEP: 50720-001, Recife, PE, Brazil.
    
Willames de Albuquerque Soares, Escola Politécnica de Pernambuco. Departamento de Física de Materiais. Universidade de Pernambuco (UPE), Rua Benfica, n° 455, CEP: 50720-001, Recife, PE, Brazil.
   
Marco Aurélio Calixto Ribeiro de Holanda, Programa de Pós-Graduação em Engenharia Civil. Escola Politécnica de Pernambuco (POLI-UPE). Universidade de Pernambuco (UPE), Rua Benfica, n° 455, CEP: 50720-001, Recife, PE, Brazil.
  
Published
15/05/2020
Section
Papers