The Determination of Anaerobic Biodegradability of Pharmaceutical Waste Using Advanced Bioassay Technique

V. Stergar and J. Zagorc-Končan

Abstract
The success of the newly developed methodology to evaluate anaerobic biodegradability of organic compounds using the Micro Oxymax respirometer and TOC analyzer made this method potentially useful for a variety of investigations. Regarding the many parameters measured during the experiment in the liquid and gas phases, the method provides good insight into the kinetics of anaerobic process and accurate mass balance, which could be obtained at any time during the assay. This method was used for determining of anaerobic biodegradability of the waste from the pharmaceutical industry-waste fermentation broth, and for the proposal of operational parameters for the start-up of the continuous process. The tests were performed in 250 ml vials at a wide range of initial substrate loading ratios (0.05-4.6 gTOC gVSS –1). The average biodegradability of the substrate was 92 % at initial loading ratios between 0.05 and 1.7 gTOC gVSS–1. At higher initial loading ratios 2,3 gTOC gVSS–1 and more, the inhibition of anaerobic biodegradation was detected. Retention times needed for a 70 % and 85 % degradation efficiency were evaluated and used as a proposal for the starting-up substrate loading rate of the continuous reactor operation. An optimum initial substrate mass concentration without an inhibition effect was estimated and the fraction of methane gas in produced biogas was calculated for each initial loading.

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Keywords
Bioassay test, wastewater treatment, operational parameters, anaerobic biodegradability, TOC