Influence of the VS-content in digested sludge on the anaerobic degradation of organic substrates at same loading rates [g/g]
In this study the influence of the content of volatile solids (= VS-content) [g/kg] in digested sludge on the anaerobic degradation of organic substrates was determined by varying the VS-content in the digested sludge for the batch-experiments by its dilution with tap-water.
As organic substrates cellulose, casein and olive oil and their mixtures in different compositions have been anaerobicaly degraded for a period of 21 days at a temperature of 35°C with digested sludge.
However, for each anaerobic degradation experiment the loading rate [g/g] (synonymous to the ratio of organic input-substrate and VS-content in the digested sludge) was set at 0,55 [g/g].
The VS-content in the digested sludge influences the anaerobic degradation: at the same loading rate of 0,55 [g/g] in all batch-experiments the biogas yields while the anaerobic degradation of mono-substrates and substrate-mixtures are lower with low VS-content in the digested sludge than the biogas-yields reached with higher VS-content in the sludge. This statement can be confirmed by the DNA- determination and the calculated amounts of living microorganism in reliance to the VS-content in the sludge.
R. Mundhenke, J.Müller, J. Schwedes (2001). Influence of the VS-content in digested sludge on the anaerobic degradation, Chem. Eng. Technol., Vol. 24, No.6, pp 635-637