[Study on physicochemical characteristics and denitrogenation of sludge during granulation]

The physicochemical characteristics and denitrogenation of sludge during granulation were investigated in SBR. It was revealed that the process of granulation can be divided into three stages, including formation, growth and mature stage. In the first stage, the settling ability of sludge was improved obviously, SVI decreased from 110 mL/g to 23 mL/g during the first 30 days; In the second phase, aerobic granule grew rapidly, the mean diameter increased to 0.82 mm from 0.25 mm in the following 15 days, the value of SOUR(h) decreased from 80 mg/(g x h) to 35 mg/(g x h), denitrification rate was highly improved during granulation, the removal efficiency of TN enhanced to 80% from 55%; In the last stage, the physicochemical characteristics of sludge and denitrogenation became stable, and the removal efficiency of TN could achieve 85%, that means simultaneous nitrification and denitrification was realized.