Organic shock loading can ...

Organic shock loading can cause nitrogen deficiency if the ammonia is low.  The microbes can form exocellular polysaccharides  which make the MLSS settle poorly.  If the MLSS concentration has dropped this causes higher F/M ratio which can exacerbate the carbon/nitrogen imbalance.  Settleometer test will result in high sludge volume index.  Check influent data for BOD:N ratio being consistently higher than 100:1    This ratio may have gone low during the shock load.  To diagnose with microscope: 1) examine floc for indicators of nutrient deficiency such as 021N filaments or tetrads  2) perform india ink stain test on floc - polysaccharides do not accept stain and appear as white globs.