The start-up strategy was designed to gradually decrease thesettling time from 20 to 10 min and thus promote granule formationwhile avoiding excess washout of biomass. Decreasing the settlingtime from 20 to 15 min on day 6 increased the EVSS concentrationfrom 135 to 246 mg L−1and decreased the MLVSS concentrationfrom over 2000 mg L−1to less than 1500 mg L−1. However, over thenext 2 days, the EVSS concentration decreased and the MLVSS con-centration stabilized. Decreasing the settling time to 10 min on day12 caused similar spikes in the EVSS concentration, followed by arapid decrease in EVSS levels 2–3 days thereafter.