A dispersed activated sludge biomass with poor floc formation and pin floc. Unusually low oxygen use, caused by poor biomass growth. Poor BOD removal. There will be a sudden increase in flagellates. The of protozoa and higher life forms will begin to die off Break-up of floc, sometimes accompanied by foaming Loss of BOD removal Filamentous bulking upon process recovery.
Filamentous bacteria are very often the first to recover after a toxic upset.
A better method of toxicity detection is the use of oxygen uptake rate testing to detect toxicity early and to find the source. Low D.O. Haliscomenobactor hydrosis, Microthrix parvicella, Nocardia spp. To determine if aeration tank or clarifier foam is due to the growth of foam- producing filamentous organisms, a sample of fresh foam should be spread thinly and evenly over a clean microscope slide, and the slide stained by Gram staining. Microthrix is a long thin filament while Nocardia is a short branched filament. Gram positive, you can easily determine which filament is responsible.