Enzymatic extraction of activated sludge extracellular polymers and implications on bioflocculation

This study examines enzyme hydrolysis, a mild, effective, but a rarely used method of extracellular polymer extraction, in removing polymers from mixed culture activated sludge flocs. Two carbohydrate specific enzymes (a-amylase and cellulase) and a protein specific enzyme (proteinase) are used during the study. First, the kinetic aspect is investigated, then enzyme dose optimization is carried out on laboratory grown activated sludge samples cultured at solids retention times (SRT) of 4 and 20 days. A more commonly used cation exchange resin (CER) extraction technique is also employed for comparison purposes. Results indicate that the extraction of extracellular polymers by enzymes is a rather quick process reaching equilibrium within only a few hours. As the doses of enzymes are increased, the extracted polymer quantities increase up to a certain dose, beyond which not much extraction is observed. The method does not cause any significant cell lysis as measured by the viable cell counts. Carbohydrate-hydrolyzing enzymes extract small amount of proteins along with the carbohydrates and protein-hydrolyzing enzyme extracts some carbohydrates together with the proteins, indicating that proteins and carbohydrates exist bound to each other in the extracellular polymer network of sludge. Enzyme extraction generally gives a lower estimate of polymers compared to the CER method, but correctly detects the trends in the polymer quantity.


Bioflocculation of activated sludge: The role of calcium ions and extracellular polymers
Sanin, Faika Dilek (Informa UK Limited, 2000-12-01)
In an attempt to identify the bioflocculation mechanisms, this study examines the role of calcium ions in flocculation of activated sludge. Two calcium specific chelants, ethylenebis (oxyethylenenitrilo)tetraacetic acid (EGTA) and sodium hexametaphosphate (HMT) are used to extract calcium ions. Both chemicals successfully extract the calcium ions from sludge structure, which is confirmed either by an increase in solution calcium concentration or by a decrease in calcium concentration in the sludge solid mat...
PCB sources, transformations, and contributions in recent Fox River, Wisconsin sediments determined from receptor modeling
İmamoğlu, İpek (Elsevier BV, 2002-08-01)
The PCB contamination in lower Fox River sediments was investigated in order to identify possible PCB sources, contributions, and transformations, using two receptor models. Congener specific sediment PCB data from sites immediately upstream of DePere dam to Green Bay that had been gathered for the Green Bay/Fox River Mass Balance Study, were used in this analysis. The first receptor model is a self training factor analysis (FA) model with non-negative constraints that was applied to identify the PCB source...
Toxicity of 2,4-D acid to phytoplankton
Okay, OS; Gaines, A (Elsevier BV, 1996-03-01)
The toxic effects of 2,4-D on Phaedoactylum tricornutum (Bohlin) and Dunaliella tertiolecta (Butcher), two species of phytoplankton well suited to bioassay studies and responsive to pollutants, were studied by monitoring changes in growth in terms of cell populations, chlorophyll fluorescence and the rate of (CO2)-C-14 assimilation. Short term bioassays, batch and continuous cultures were studied. Pure 2,4-D acid appeared more toxic than the commercial amine form of the herbicide but this may have been due ...
Nickel sorption by acclimatized activated sludge culture
Arican, B; Yetiş, Ülkü (Elsevier BV, 2003-08-01)
The sorption of Ni2+ by acclimatized activated sludge treating Ni2+ bearing wastewater was investigated using a once-through completely mixed tank reactor. The culture developed from sewage was acclimatized to 85.2 mumole/L Ni2+ influent concentration by stepwise increases, at a low dilution rate 0.11/h. Acclimation was found to enhance the sorptive capacity of the activated sludge. In fact, at all of the intermediate concentrations, percentage Ni2+ adsorbed by the biomass and also the sorptive capacity of ...
Metabolic reaction network of Pichia pastoris with glycosylation reactions: Flux analysis for erythropoietin production
Eskitoros, Melda S.; Ata, Ozge; Çalık, Pınar (Wiley, 2014-11-01)
BACKGROUND: Biochemical reaction network of Pichia pastoris was improved by including N-glycosylation pathway reactions to determine the intracellular reaction rates for glycosylated protein production.
Citation Formats
M. Sesay, G. Özcengiz, and F. D. Sanin, “Enzymatic extraction of activated sludge extracellular polymers and implications on bioflocculation,” WATER RESEARCH, pp. 1359–1366, 2006, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/38405.