Sludge Metabolism Behaviors of Anaerobic-oxic (A/O) Activated Sludge System under Different P/C Load

Autor: Chun-Hui Su, 蘇峻輝
Rok vydání: 2007
Druh dokumentu: 學位論文 ; thesis
Popis: 95
Starting-up of newly established Enhanced Biological Phosphorus Removal (EPBR) system requires seeding sludge from other biological treatment plant so as to obtain a PAO-enriched sludge. Some scholars believe PAOs have to coexist with anaerobic bacteria, as PAOs can only take up short chain fatty acid in the anaerobic stage. Some researches mention that micro flora structure of PAO-enriched sludge is very complicated while Betaproteobacteria and Actinobacteria are the main superiority micro flora. However, whether seeding with waste sludge from traditional biological treatment system (sewage treatment, industry waste water treatment plants) can have the biologically phosphorus removal result of the newly established biological system is still left for further study. Therefore, the research aims at verifying this by seeding different sludge to anaerobic-oxic (A/O) activated sludge system. After continuous operation of 3 folds of SRT (i.e. 40 to 60 days), the A/O systems become stable and we have similar process performance for the EBPR system. From the results of the batch tests before seeding, almost no phosphorous release/uptake was obseved. However, batch tests after seeding demonstrated excellent phosphorous removal；which means PAOs exist in various traditional active sludge system. Finally, same influent substrate and operation conditions can obtain, PAO-enriched sludge with similar microbial. It has long been prove although the sludge source is different that anaerobic-oxic (A/O) activated sludge system enhances biologically phosphorus removal, although the effect is often hindered due to some factors. The main reason is the competition between Glycogen Accumulating Organisms (GAOs) and Phosphate Accumulating Organisms (PAOs). The organic substances in influent water of common waste water treatment plants are complicated. When the influent water is in anaerobic stage, fermentation reaction starts. The fermentation products includes acetate, propionate, and lactate, etc. It is, therefore, suspected whether different organic substances affect the biologically phosphorus removal of the system. Therefore, this study investigated the stoichiometries and kinetic constants of PAO-enriched sludge by using batch tests fed with acetate, propionate, glucose, and latate. When acetate and glucose are the single substrate, they do not inhibit the substrate uptake of sludge in three different P/C ratios. However, with propionate and lactic as single substrate, higher substrate concentration exhibited self inhibition effects. We have listed the kinetic parameter of sludge from three ratios of P/C on various substrates in the following table. Besides, results show that different substrate concentrations do change their stoichiometry relation. carbon kinetic parameters GAOs (2.8/600) PAOs (11/600) PAOs (22/600) source Acetate qm a 0.55 0.70 0.69 Ks b 153.98 132.13 93.67 Glucose qm 4.00 4.17 4.04 Ks 176.65 211.80 253.89 Propionate qm 1.47 1.60 1.30 Ks 70.73 47.85 20.26 KSI c 176.18 124.42 111.48 Lactate qm 0.84 0.83 0.76 Ks 22.86 23.60 44.41 KSI 219.94 138.48 82.75 a..maximum specific substrate utilization rates (mg/g MLSS/min) b. saturation constant (mg/L) c. inhibition constants (mg/L) Experimented results infer that acetate in biological treatment influent does help biologically phosphorus removal. As for glucose, the maximum specific substrate utilization rates of the three sludge are similar. It is speculated that glucose influent shall not make impacts on EPBR. Although maximum specific substrate utilization rates in propionate has no fixed trend, as PAOs is more affinitive to propionate from KS, it is speculated that propionate in influent does not make much difference on EPBR. In lactic experiment, it is found GAOs has better maximum specific substrate utilization rates and KS. Yet, PAOs can accumulate more PHAs. Therefore, one can still not be sure of the impact on EPBR from lactate influent.
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