Nicole Fischer

Experimental investigations on the influence of physico-chemical parameters on anaerobic degradation in MBT residual waste Nicole Fischer

In this work, MBT residual waste was used for experimental studies to investigate the influence of crucialparameters influencing biochemical processes in anaerobic degradation in residual wastes from MBT. Themoisture content is one of the most critical parameters influencing biogas production in waste as well asnutrient transport. Batch experiments were carried out to correlate moisture content and biogas production inMBT residual waste. Moreover, quantification and monitoring of heterogeneous moisture distribution in alandfill body is critical for mechanical landfill stability and landfill gas emission control. For quantitativelymonitoring in-situ moisture distribution in in MBT residual waste, a novel geoelectrical technique wassuccessfully applied and evaluated on laboratory scale. The pH development in leachate from MBT residualwastes and the relating acid buffering intensity was found to be important for facilitating biochemicalconversion of solid organic carbon matter to biogas. At unadjusted conditions, a positive correlation betweenstrength of acidification phase and biogas production, especially methane production, could be found. Thereby, the acid buffer intensity of MBT residual wastes proved to be crucial for pH stabilisation. Due tomaximum cumulative biogas production at neutral pH, pH regulation at pH 7 is recommended for wastetreatment in MBT plants and landfill bioreactors. The bioavailability of metabolic intermediates wasinvestigated with regard to their sorption behaviour on MBT residual wastes. Alcohols of a homologousseries with increasing octanol-water partition coefficients POW were used as surrogates for carboxylic acids. Activated carbon was used as a reference sorption system due to its high specific surface area. Bydetermining the distribution coefficient KD, the bioavailability factor Bf was quantified and denotes thatbioavailability of the surrogates was practically unlimited. Transferring these results to intermediates of theanaerobic degradation with similar log POW values, e.g. acetic acid and propionic acid, reveals thatbiodegradation of certain organic substrates e.g. acetic acid or propionic acid can be considered unconfinedin MBT residual waste.