Effect of the food-to-microorganism (F/M) ratio on the formation and size of aerobic sludge granules

► Aerobic sludge granulation at F/M ratios from 0.3 to 1.1 g COD/g SS-d. ► Linear correlation between the mean size of aerobic granules and the F/M applied. ► Increasing the F/M ratio (>1.1 g COD/g SS-d) for rapid aerobic granulation. ► Reducing the F/M (<0.3 g COD/g SS-d) for maintenance of small and healthy granules.