Untersuchungen zum mikrobiellen Abbau von chlorierten Aromaten in einem Suspensions-Membranreaktor

Abstract

Due to the circulatory management law in Germany originated a greater demand for environmental techniques integrated in production processes. In this work a new Suspensions-Membranereactor (SMR) which eliminates hard degradable pollutants out off a mixture of wastewater selectively was investigated and compared with a conventional Airloop-Reactor (AIR). Initial, the microflora responsible for the degradation of the model pollutants 3-chlorobenzoate (3-CBA) and 4-chlorophenol (4-CP) was described. 173 isolated bacteria were characterized morphologically and physiologically. The most important species were identified as Variovorax paradoxus, Alcaligenes denitrificans, Pseudomonas fluorescens, Burkholderia pseudomallei and Xanthomonas campestris. To describe the pathways of the degradation different methods were combinated. Examinations of the reaction kinetics and the use of UV-spectroskopy, ion chromatography, HPLC and the newly developed method HPLC coupled with mass spectrometry proved an initial dechlorination followed by an ortho-ring cleavage of an not detectable aromatic intermediate as the main pathway in the SMR. The dehalogenation was the limiting step in the degradation of 4-CP but not of 3-CBA. The comparatively high reaction rate of this compound only depended on the conversion of the aromatic metabolites. The degradation of both compounds could be inhibited by too high substrate concentrations, but no halogenated metabolites and "dead-end-products" occurred supposing a high operation stability. The examinations of culturable cells (CFU), total counts, metabolic active cells and physiological capacities indicated not only a higher amount of bacteria but also the more efficient organisms in the SMR. Considering the quicker turnover rates in comparison to the AIR the SMR showed a better growth of a specialized microflora and a better selective degradation of wastewater compounds.