Waste Activated Sludge

RESEARCH PROGRAMS WERE UNDERTAKEN TO ESTABLISH THE STABILITY OF WASTE ACTIVATED SLUDGE GENERATED FROM WASTE ACTIVATED SLUDGE TREATMENT PLANTS, BOTH NUTRIENT REMOVAL AND CONVENTIONAL, AND DETERMINE WHAT FURTHER TREATMENT IS REQUIRED TO PRODUCE A SUBSTANTIALLY STABILISED (IE. NON-ODOROUS) SLUDGE. IT HAS BEEN PREVIOUSLY THOUGHT THAT WASTE ACTIVATED SLUDGE FROM EXTENDED AERATION PLANTS (SLUDGE AGE OF APPROXIMATELY 25 DAYS) WAS SUFFICIENTLY STABILISED TO PERMIT DEWATERING AND STOCKPILING WITHOUT ODOUR GENERATION. HOWEVER, EXPERIENCE AT A NUMBER OF TREATMENT PLANTS WITH LARGE UNAERATED MASS FRACTIONS FOR BIOLOGICAL REMOVAL OF NITROGEN AND PHOSPHORUS HAS DEMONSTRATED THAT THESE WASTE ACTIVATED SLUDGES ARE GENERALLY ODOROUS.