Abstract:In order to find a new way of excess sludge utilization, sludge extract was used in the biosynthesis of demusifier by Alcaligenes sp. S-XJ-1. It was practical to cultivate highly efficient demulsifying strains in sludge extract. Sludge extract was obtained by the untrasound condition of 443~56647kJ/kg TS. In sludge culture medium, maximun concentration of ammonia nitrogen, organic nitrogen and phosphorus were 171.94,142.20 and 76.29mg/L. Sludge extract contained metallic elements such as K, Ca, Mg, Fe that were essential to the synthesis of S-XJ-1. After 7days cultivation, the biomass of S-XJ-1in sludge extract was 0.3%~68.3% higher than that in MMSM. Highest yield (2.03g/L) was obtained when specific energy was 56647KJ/kg TS. pH buffering capacity and concentration of organic nitrogen might have a great impact on the yield. The bio-demusifier produced with sludge extract had a quite stable demusifying ration of 80%, of which the CSH and C/N did not show much difference to that with MMSM.