Kemicond – Improvement of the Dewaterability of Sewage Sludge by Chemical Treatment

The Kemicond process for sludge conditioning consists of a chemical treatment with sulphuric acid and hydrogen peroxide at a pH-value around 4 followed by a dewatering unit. It is shown that through the chemical treatment of ferruginous digested sludge the dewaterability, measured in laboratory experiments as CST-value, can be improved. From the results of the experiments, it is concluded that the Fenton's reaction by oxidising organic matter and the formation of iron hydroxo complexes are important reaction mechanisms. Further, the organic matter is changed by the acid-oxidative process. With the improvement of the dewaterability, it is possible to achieve a higher TS concentration, which effects a reduction of the sludge volume.