Biological treatment of highly foaming pharmaceutical wastewater by modified bubble-column under mechanical foam control

Activated sludge treatment of highly foaming pharmaceutical wastewater was carried out with modified bubble columns equipped with a mechanical foam-br eaker (MFRD). The geometry of the bubble column was modified based on the f oam breaking mechanism of the MRFD in order to improve the foam breaking ca pacity and hence to enhance the treatment capacity. Four types of modificat ions were examined. The activated sludge treatment of the wastewater with t he modified columns was successfully carried out with COD removal efficienc y about 90% at BOD loading of 4 g/Ld. Little effect of the mechanical foam control on the sludge settling characteristics was observed. The column mod ification significantly reduced the power required for foam control. The ma ximum power decrement of 75% was attained. Furthermore, oxygen transfer was found to be facilitated in the modified bubble columns. The results are ex pected to be helpful for economic and effective treatment of highly foaming organic wastewater.