Comparison of methods for the biodegradability evaluation of soluble and insoluble organochemicals.

Pyridine and nitrilotriacetic acid sodium salt as models of soluble compounds and linear dodecylbenzene, branched dodecylbenzene, and stearic acid as models of insoluble compounds were compared for their biodegradability in three tests: the ODCE modified test and the Sturm and enrichment culture tests. The degradation of soluble compounds was measured as dissolved organic carbon removal and CO2 evolution, while for the insoluble compounds, which were tested only in the Sturm test, CO2 evolution was determined. The individual tests were characterized by comparing their results with those obtained in the others. Comparable biodegradation values higher than 90% were obtained for the soluble compounds. The Sturm test proved to be very suitable for the evaluation of biodegradability of either soluble or insoluble compounds.