WWTP DATE ESS (mg/L) MES (g/L) Bulking (*) FLOCCULANT TY (%) overshoot STEP 0 22-11-2012 8 4.7 NO NO 5.3 STEP 1 06-10-2012 10.3 5.0 YES NO 0 STEP 2a 11-09-2012 13.4 4.5 YES NO 0 STEP 2b 26-09-2012 7.6 4.4 YES NO 1.4

Table 1: For reasons of confidentiality, the names of the treatment plants were encrypted. “Bulking” indicates any type of floating material (foaming, filamentous bacteria, etc.). All the WWTPs are located in central Belgium. STEP2a and STEP2b are the same plant, under two different working conditions.