Removal of Non-Ionic Surfactants in an Activated Sludge Sewage Treatment Plant

Non-ionic surfactants (NS) are a major source of synthetic organic carbon discharged into surface water. The aim of this work was the investigation of the influence of different factors on NS removal in an activated sludge sewage treatment plant (STP). Tensammetric analytical tools were used for fast and inexpensive NS determination. The STP in Blonie (Poland) was the subject of research. The STP's reconstruction caused a spectacular lowering of NS concentration in the treated sewage; however, in subsequent years, NS concentration significantly rose, due to a dramatic increase in the NS load. The NS load reduction in the reconstructed STP was relatively high (93.4-97.9 %). The presence of exclusively alcohol ethoxylates was confirmed in the raw sewage. The residual NS concentration in treated sewage is dependent on the hydraulic retention time, the NS load and on the sludge volume index.