SOUZA, A. R.; http://lattes.cnpq.br/9243117754040261; SOUZA, Alice Rocha de.
Abstract:
The association of anaerobic pre-treatment, for example, in a UASB reactor with
activated sludge systems for post treatment has been an object of several studies and is
being applied in practice of waste water treatment systems. However, activated sludge
systems fed with different substrates (for example raw or digested sewage) tend to produce
sludges with different mechanical and biological characteristics. In order to evaluate the
characteristics of the autotrophic fraction of sludge generated from different substrates an
experimental investigation was carried out, where three activated sludge systems of the
sequencing batch reactor (SBR) type, were operated with raw sewage, digested sewage an
ammonium solution as substrates. The systems were evaluated with respect to the
suspended solids and organic material and ammonium removal efficiencies, as well as the
settleability and activity of the sludges. The Volumetric Sludge Index (VSI) and the
Oxygen Uptake Rate (OUR) were used for the assessment of the mechanical and biological
characteristics. The obtained results during the experimental investigation showed that the
systems were equally efficient in the removal of organic material and suspended solids
with efficiencies of 83% for COD and 91% for TSS. The settleability of the sludge was
considered good for the system operated with digested sludge and fair with the system
operated with raw sewage. However, the autotrophic sludge did not exhibit high biological
activity having values of the specific growth rate constant for Nitrossomonas (p*,) in the
range of 0,31 d"1 for the system fed with raw sewage and 0,21 d"1 for the system fed with
ammonium substrate, whereas no activity was detected in the system fed with digested
sewage.