Abstract:
The disintegration of waste activated sludge (WAS) by alkaline pre-treatment (alkalization) was carried out in batch reactors in this
study. The influences of operating conditions (sludge concentration, NaOH dosage and pre-treatment time) on the sludge
disintegration, the release of extracellular polymeric substances (EPS) and the dewatering and settling properties of sludge were
investigated at room temperature. The alkalization was determined to be an effective disintegration method. Optimum operational
conditions were found as 0.10 N NaOH, 0.5 h pre-treatment time and 1.0% total solid (TS) content of the sludge. It was also
observed that the alkaline sludge disintegration occurred in two stages: the rapid disintegration stage in the first 0.5 h and the
subsequent slow disintegration stage in the remaining part of the pre-treatment time. Therefore, the alkalization process was
simulated via a two-phase kinetic mathematical model in order to predict the process performance. The suggested mathematical
model was proven to be a useful tool for predetermining the efficiency of alkalization process and for designing the process.