Significance and Use
Secondary wastewater treatment using activated sludge is one of the most important biological treatment processes in use today. The porous pot simulates the activated sludge sewage treatment process in the laboratory and provides data that can be used to predict the fate of organic compounds in full scale plants.
A good correlation between the laboratory test and full scale plants is achieved by the use of primary effluent or settled domestic sewage and controlling key parameters in ranges typical of such treatment process. These parameters include temperature, pH, DO concentration, hydraulic residence time (HRT) and sludge retention time (SRT).
Scope
1.1 This test method covers simulating the activated sludge sewage treatment process and therefore gives a measure of the extent of biodegradation or removal likely to occur during sewage treatment.
1.2 Assessment of treatability or biodegradability, or both, of water soluble organic compounds in the porous pot test requires dissolved organic carbon (DOC) measurements or specific chemical analysis.
1.2.1 Dissolved organic carbon (DOC) measurements, relative to the controls, can be used to calculate the removal of the test chemical or water soluble residues by the porous pot treatment (see 12.3). The DOC measurements do not identify water soluble chemicals. Specific chemical analysis, on the other hand, can be used to identify and quantify the parent test chemical or (if standards are available) any water soluble residues formed by the porous pot treatment. A specific chemical analytical method must have a limit of detection (LOD) ≤0.1 mg/L in water or ≤0.1 mg/Kg in solids.
1.3 The feature that distinguishes this test from other activated sludge simulation tests is the retention of the activated sludge in a porous liner, that eliminates the need for a secondary clarifier and facilitates control of the critical parameter, the sludge retention time (SRT).
1.4 Porous pots can be completely sealed and tests using 14C-labeled test compounds are then possible. Carbon dioxide in the exhaust gas and bicarbonate in the effluent can be used together to assess the extent of mineralization, and levels of radiolabel in the sludge and in the aqueous phase may also be determined.
1.5 By simultaneously measuring the efficiency of the pots in removing DOC, it is also possible to determine whether the test compound has any adverse effect on normal sewage treatment processes.
1.6 The SI units given in parentheses are for information only.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements see Section 6.
