**5.5 Observation of microbial growth and biofilm development in industrial wastewater**

Four microbial cultures have been prepared utilizing tannery wastewater as substrate. Specifically:


The substrates have been collected in a flask and sterilized at 121°C for 15 minutes, then inoculated with at 5% with a microbial sludge collected from the mixed sludges. Microbial growth has been promoted as described previously, as well as for the procedure for air blowing, fragments collection, evaluation of attachment, clarification and foam formation. The development of microorganism has been checked after 24 hours according to the scalar dilution's method and PCA bacterial count on Petri dish (**Table 5**).
