EXTRACELLULAR POLYMERS IN GRANULAR SLUDGE FROM DIFFERENT UPFLOW ANAEROBIC SLUDGE BLANKET (UASB) REACTORS

Thermal extraction was used to quantify extracellular polymers (ECP) i n granules from anaerobic upflow reactors. The optimal time for extrac tion was determined as the time needed before the intracellular materi al gives a significant contribution to the extracted extracellular mat erial due to cell lysis. ECP contents of 41 to 92 mg.g(-1) volatile su spended solids of granules were found depending on the type of granula r sludge examined. The content of polysaccharides, protein and lipids in the extracted ECP was quantified. Furthermore, the different methyl esters of the lipids were determined and quantified. Lower amounts of polysaccharides and proteins were found in the extracellular material from granules grown on methanogenic and acetogenic substrates compare d to granules grown on more complex substrates. In contrast, the lipid content was lower on complex substrates. Changing the feed of an upfl ow anaerobic sludge blanket reactor from a sugar-containing waste-wate r to a synthetic waste-water containing acetate, propionate and butyra te resulted in a decrease in both the protein and polysaccharide conte nt and an increase in the lipid content of the extracellular material. Furthermore, the amount of protein and polysaccharides in the ECP fou nd under mesophilic conditions was significantly higher than under the rmophilic conditions, while the lipid content was lower.