Small waste water treatment plants evaluation and remarks on the European fitness for use procedure

As part of the development and assessment of a procedure for the evaluation of systems for treatment of domestic waste water, SSTC has given an assignment to CEBEDEAU, FUL, Vito en WTCB. Vito's tasks include making operational a test rig, in conformity with the norm, for testing 2 commercial units, testing 4 types commercial installations (at 2 loadings) on-site and making a global evaluation and recommendation for the CEN-proposal (final draft of the European norm prEN 12566-3). Routine monitoring and sampling, washing machine tests, peakflow discharge and several stress tests are defined within the CEN-proposal. During 2 years, Vito has been testing and monitoring 3 activated sludge systems, 2 rotating biological contactors and 5 submerged aerated filters. The research is still going on. This paper gives an overview in the main conclusions and recommendations for the development of the proposed CEN-procedure. A flexible testing schedule with well-defined stress tests could give the testing laboratory more space for thorough screening and evaluation. Moreover, performing an evaluation on test rig under standardized conditions is often not comparable with on-site monitoring, due to uncontrollable facts. It would be interesting to a small waste water treatment system monitor on a test rig, completed with an efficient on-site control.