IS CBOD5 TEST VIABLE FOR RAW AND SETTLED WASTE-WATER

In recent years, the carbonaceous biochemical oxygen demand (CBOD5) test has been employed to determine the carbonaceous fraction of the biochemical oxygen demand (BOD5) of final effluents in nitrifying systems. More recently, several states have required plants to analyze influents using the CBOD5 test to determine whether the 85% removal rule is being attained. The 1989 Standard for the Examination of Water and Wastewater Methods does not suggest-nor does the Environmental Protection Agency (EPA) CBOD5 procedure studies justify-the use of the CBOD5 test for raw and settled wastewaters. Analysis of operational data from several plants demonstrates that the CBOD5( )test seriously understates the true strength of influent and primary effluent wastewaters as defined by BOD5 and chemical oxygen demand (GOD) tests. The result of using CBOD5 data could result in a 20-40% underdesign as well as cause nonexistent effluent violations of the EPA 85% removal criteria rule. The conclusion was that CBOD5 is an improper test for influent and settled raw wastewater.