A sludge purging procedure that increases the robustness of upflow anaerobic sludge blanket reactors in sewage treatment

  • R. F. Gonçalves
  • L. M. LouzadaEmail author
  • R. Wanke
Original Paper


This work proposes a sludge purging procedure from upflow anaerobic sludge blanket reactors in small wastewater treatment plants. The following characteristics of the anaerobic sludge supported its development: specific methanogenic activity, biodegradability and dewaterability. The sludge samples from the reactor blanket zone presented low specific methanogenic activity, low biodegradability and good dewaterability. On the other hand, sludge samples from its bed zone showed higher biodegradability and specific methanogenic activity, as well as equivalent dewaterability and excellent sedimentability. These characteristics indicate that the common practice of sludge purging from the bed zone is a mistake and must be avoided. Nevertheless, the sludge blanket usually presents high water contents (total solids < 3%), which can overload hydraulically the drying beds. To prevent this problem, the sludge purge from the blanket zone should be fractionated into three discharges of lower volume during the first 3 days of the dewatering cycle.


Dewatering Drying bed Specific methanogenic activity Sludge purge Upflow anaerobic sludge blanket 



The authors acknowledge the financial support provided by the following agencies that support scientific and technological development in the country: National Council for Scientific and Technological Development (CNPq), Espírito Santo Research Foundation (FAPES) and Project and Study Funding Agency (FINEP) (Grant Number: 01.06.0593.00—CHAMADA PÚBLICA MCT/FINEP—AÇÃO TRANSVERSAL, BRAZIL).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Islamic Azad University (IAU) 2019

Authors and Affiliations

  1. 1.Department of Environmental Engineering, Technology CenterFederal University of Espírito SantoVitóriaBrazil
  2. 2.Fluxo Engenharia AmbientalVila VelhaBrazil

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