Anaerobic biodegradability: Results of a Dutch inter-laboratory exercise

Abstract

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In 1990/1991 a round-robin test was carried out in the Netherlands to investigate s simple serum bottle technique for anaerobic biodegradability, organized by the RIVM. Six laboratories participated in this inter-laboratory exercise and tested four chemicals, according to methods published earlier by the RIVM (1987) and ECETOC (1988). The most satisfactory and simple procedure to evaluate the degree of anaerobic mineralization is to combine two parameters that can easily be measured, i.e. the net gas production and the increase of dissolved inorganic carbon. This approach is more succesful than monitoring the evolved methane. Both procedures to wash the anaerobic sludge are effective in reducing the blank gas production due to the sludge. The blank values are all in the surprisingly small range of 20 and 100 ml per g sludge. Polyethyleneglycol-400 is a suitable positive reference compound. Aniline was most persistent but it also showed toxic effects. 2-Propanol was mineralized in most laboratories after a lag varying from 1 to 4 months. 2-Aminophenol is an erratic compound: participants reported persistence during the test period, toxic effects and (partial and ultimate) biodegradation.