Hydraulic Retention Time Influence on Improving Flocculation in the Activated Sludge Processes Through Polyelectrolytes

  • Cristina E. Almeida-Naranjo
  • Patricio J. Espinoza-MonteroEmail author
  • Marcelo I. Muñoz-Rodríguez
  • Cristina A. Villamar-Ayala


Hydraulic retention time (HRT) influence improving sludge flocculation with adding the polyelectrolytes (non-ionic, anionic, and cationic) was studied on an activated sludge (AS) system fed with synthetic domestic wastewater (SDW), dairy industry wastewater (DIW), and caramel industry wastewater (CIW). The sludge volumetric index, food/microorganism ratio (F/M), and mixed liquor volatile suspended solids at different HRTs (6, 8 and 10 h) were monitored on an experimental model. Results showed that both SDW and IW had the best sludge flocculation conditions at 8 h and 100 mL of non-ionic polyelectrolyte (0.2 mg L−1). In addition, this phenomenon reached the organic matter removal efficiencies of 95.9, 95.7, and 94.2% for SDW, DIW, and CIW, respectively. Therefore, optimum HRT increased the organic matter removal efficiencies by 10%, sludge concentration by 37% (22–55%), and F/M ratio by 70%. Moreover, the polyelectrolytes used in AS improved the sludge flocculation by 2.9 times.


Activated sludge system Sludge flocculation Polyelectrolytes Synthetic domestic wastewater Industrial wastewater Sludge characteristics 



This work was supported by collaboration in the experimental research. The authors thank Mr. Jorge Escobar Ortiz for designing the reactors used in this study and to Ms. Jennifer Guerrero for the collaboration in the laboratory work.


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Copyright information

© Springer International Publishing AG Switzerland 2017

Authors and Affiliations

  • Cristina E. Almeida-Naranjo
    • 1
  • Patricio J. Espinoza-Montero
    • 1
    Email author
  • Marcelo I. Muñoz-Rodríguez
    • 1
  • Cristina A. Villamar-Ayala
    • 1
  1. 1.Centro de Investigación y Control Ambiental, Departamento de Ingeniería Civil y AmbientalEscuela Politécnica NacionalQuitoEcuador

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