Prior to installation of the Microbac Bioreactor at the Rhone Poulenc Agriculture site, laboratory studies and a site trial were undertaken to demonstrate the effectiveness of the submerged, fixed-film Bioreactor system for the removal of acetone and ammonia in the Rhone Poulenc wastewater stream.

The main benefit of undertaking projects in a phased manner is that it allows the client to assess results at each stage and only make commitments to the full-scale treatment system if results demonstrate the viability of the system. In addition, the results are used by Microbac's process design engineers to accurately size the full-scale treatment plant.

The two Bioreactors at the Rhone Poulenc site run in parallel, allowing the wastewater to be re-directed to one unit only in cases of low flow or for major maintenance activities on a Bioreactor's aeration system. Organic removal occurs at the inlet end of the Bioreactor with nitrification zones, for ammonia removal, at the discharge end of each unit.

The excellent performance of the Bioreactors is coupled with low maintenance requirements and, hence, little daily input is required by the client.

Samples of wastewaters are taken by the client on a weekly basis and analysed by Microbac's laboratories to monitor the Bioreactor's performance. Samples of biomass are also taken at regular intervals to ensure optimum performance of the biological system.

After 10 years in service, the Bioreactors continue to meet consent discharge limits for COD, BOD, acetone and ammonia on a continuous basis and have required little attention from on-site personnel.