Phosphorus defficiency and sludge bulking.

Separation by settling is one of the most troublesome stages of an activated sludge process. A decrease in the efficiency of separation of microbial biomass from the treated effluent causes a decrease in the overall efficiency of the treatment plant. One of the most common problems in activated sludge systems to negatively influence the settleability is sludge bulking which can be defined as non-settling situation of microbial mass.