DEVELOPMENT OF EPAS NEW METHODS TO QUANTIFY VECTOR ATTRACTION OF WASTE-WATER SLUDGES

EPA's 1979 and 1993 sludge regulations require that sewage sludge be r educed in vector attraction before it can be applied to the land. In t he 1979 regulation, satisfactory vector attraction reduction (VAR) cou ld be demonstrated if treatment processes reduced the volatile solids content of sludge by 38%. The 1993 regulation adds two alternative tes t methods for aerobic sludges for determining whether VAR has been ade quate. In the first method, specific oxygen uptake rate (SOUR) of the sludge must be < 1.5 mg O-2/hr/g total solids, and in the second metho d, the additional volatile solids reduction (AVSR) that occurs when th e sludge is further digested for 30 days must be < 15%. Experimentatio n with the new tests is described. Comparisons among the three methods showed that the 38% VSR requirement and the SOUR test were equivalent only near 20 degrees C. The AVSR test was more conservative than eith er of the other tests.