Research On Aerobic Digestion Process And The Sludge Reduction Pathway

The microbes use their own substance to catabolism and anabolism in aerobicdigestion. The amount of cell degradation is greater than the amount of cell synthesis, sothat achieve the goal of sludge reduction. This process include endogenous respiration,microbial dissolved and recessive growth of little cell. But there is no definiteconclusion which method is most important in the process of sludge reduction. Thisresearch is to discuss the mainly method of sludge reduction of aerobic digestion. Theresults are as follows.Put forward the standard concentration calibration method for the effect of organics(such as formic acid, acetaldehyde, acetone, isoamyl acetate etc.) on the polysaccharidedetermination using anthrone-sulfuric acid method. The mothod can effectively reduceerrors and improve measurement accuracy.Comparative analysis of the contribution of endogenous respiration and cell lysisby measuring VSS in aerobic digestion, and found that the contribution to sludgereduction of cell lysis is51%~88%, while the endogenous respiration contributed only12%~45%. Cell lysis is the main way of sludge reductions in aerobic digestion.The reduce rate of total cells (DAPI)of endogenous respiration test is2.3×106a/d atthe beginning of the aerobic digestion, which is lower than the cell lysis test of2.9×106a/d.The DAPI of endogenous respiration test decreased by20%,while cell lysistest decreased by25%. It suggests that the contribution of cell lysis is more apparentthan endogenous respiration. The DAPI of the two tests decreased by43%in themid-aerobic digestion. Both of them are consistent. The reduce rate of two tests are small in the end, and the decrement of DAPI in the sludge is very weak.The study also discussed the change of the EPS in sludge, and found that thedegradation rate of EPS in two tests is consistent. The contribution to the sludgereduction can be neglected because of the little content of EPS. Contrast of analysisresults of two tests, and found that the amount of polysaccharide and nucleic acid ofendogenous respiration test is higher than hydrolysis test, while the amount of protein islower.Through the study on sludge composition, it is concluded that the endogenousrespiration and cell lysis mainly degrade the polysaccharides and proteins in the sludgewith the lack of the substrate, while the degradation of the nucleic acid and EPS is verylittle.The SMP produced in the process of endogenous respiration is higher thanhydrolysis. Both of them reached a peak on the sixth day, and then gradually declining.The protein and polysaccharide of hydrolysis test were significantly less thanendogenous respiration test before6days, while grater after10days.