Microbial processes underlying the PETRO concept (trickling filter variant)

Natural phenomena underlying the operation of the PETRO (pond enhanced trea tment and operation) system and its trickling filter (TF) in particular hav e been elucidated. Data obtained strongly indicate that the microalgae apar t from bacteria, fungi, protozoa and rotifers play an important role within the TF biofilm consortium. Their stress-induced biofilm slime production u nder heterotrophic conditions in the TF, appears to greatly facilitate floc culation of solids which results in high performance of the TF, the clarifi er and the system as a whole. (C) 1999 Elsevier Science Ltd. All rights res erved.