Monitoring protozoa and metazoa biofilm communities for assessing wastewater quality impact and reactor up-scaling effects

The succession of biofilm communities with special emphasis on ciliates, ro tifers, and nematodes was monitored for half a year and compared to differe nt operating conditions in order to evaluate plant performance and effect o f up-scaling lab scale to large scale reactors. Ciliates and metazoa are ab le to rapidly change their communities as a reaction to changed plant opera ting conditions as has been proven true by comparing lab scale and pilot sc ale reactors. Even slight operational changes are causing major shifts in b iofilm communities. Nematodes and rotifers in lab scale and large scale rea ctors seem to be in competition with peritrich ciliates. In both lab scale and pilot scale systems ciliates of the subclass Peritrichia proved to be d ominant and thus to play an important role in both the species composition of the biofilm biocenosis and biofilm structure. Interpretation of biocenos is composition changes far large scale reactors is much more complex than f or lab scale reactors. This conflicts with up-scaling of lab scale results to full scale reactors.