Fatty acids of lipid fractions in extracellular polymeric substances of activated sludge flocs

Lipids ◽  
2003 ◽  
Vol 38 (10) ◽  
pp. 1093-1105 ◽  
Author(s):  
Arnaud Conrad ◽  
Merja Kontro ◽  
Minna M. Keinänen ◽  
Aurore Cadoret ◽  
Pierre Faure ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Extracellular Polymeric Substances ◽  
Sludge Flocs ◽  
Lipid Fractions

scholarly journals Improvements on activated sludge settling and flocculation using biomass-based fly ash as activator

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Xiaoqian Chen ◽  
Fangong Kong ◽  
Yingjuan Fu ◽  
Chuanling Si ◽  
Pedram Fatehi
Keyword(s):  
Fly Ash ◽  
Activated Sludge ◽  
Extracellular Polymeric Substances ◽  
Sem Analysis ◽  
Sludge Flocs ◽  
Before And After ◽  
Number Of Microorganisms ◽  
Adverse Influence ◽  
Settling Performance ◽  
Sludge Settling

Abstract Biomass-based fly ash and wastewater are undesired products of the pulping industry. Recently, the use of biomass-based fly ash as an adsorbent (i.e., a valued material) for constituents of wastewater effluents was reported. In this work, the settling performance and properties of activated sludge were studied in the presence of fly ash. Upon mixing, fly ash increased the zeta potential of the sludge from −31 mV to −28 mV, which was due to the release of cationic ions from fly ash in the sludge suspension. The sludge settling and its flocculation affinity were improved through the complexation of flocs and released cation ions from fly ash. The relationships between the protein/polysaccharide (PN/PS) ratio and the content of extracellular polymeric substances (EPS) as well as the ratio and the properties of the sludge flocs were determined. A correlation between the total loosely bound-EPS (LB-EPS) content and the effluent suspended solids (ESS) (Pearson’s coefficient, rp = 0.83) was observed. The performance of sludge flocculation and settling were much more closely correlated with LB-EPS than with tightly bound EPS (TB-EPS). Scanning electron microscopy (SEM) analysis of sludge flocs before and after EPS extraction showed that the sludge flocs contained a large number of microorganisms, mainly Bacillus and Cocci. The amount of LB-EPS had an adverse influence on bioflocculation, effluent clarification and sludge settling affinity. The sludge properties had a moderate relationship with the PN/PS ratio of LB-EPS. Also, no correlation could be established between the ratio and the TB-EPS content.

Transformation of lipids in activated sludge

2001 ◽  
Vol 43 (1) ◽  
pp. 165-172 ◽  
Author(s):  
T. E. Dueholm ◽  
K. H. Andreasen ◽  
P. H. Nielsen
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Activated Sludge ◽  
Chain Fatty Acid ◽  
Hydrolysis Rate ◽  
Long Chain Fatty Acids ◽  
Long Chain Fatty Acid ◽  
Sludge Flocs ◽  
Uptake Rates ◽  
Long Chain

Transformation of lipids in activated sludge treatment plants is of interest for two reasons: lipids contribute 30–40% of the chemical oxygen demand (COD) in wastewater, and they may stimulate the growth of filamentous microorganisms in nutrient removal activated sludge plants. The transformation of lipids was investigated under aerobic and anoxic conditions by measuring the oxygen and nitrate uptake rates (OUR and NUR). The maximal OUR and NUR of long-chain fatty acid was found to be at the same level as acetate indicating that long-chain fatty acid was as easily consumable. However, the adsorption of long-chain fatty acid to surfaces of sludge flocs made it difficult to determine initial uptake rates of long-chain fatty acids. It was not possible to describe the hydrolysis rate of triacylglyceride by OUR and NUR to long-chain fatty acids because the hydrolysis rate was very slow. For a better description of the processes involved in transformation of lipids, a conceptual model was suggested. The processes in the suggested model were the adsorption/desorption of both triacylglyceride, and long-chain fatty acid onto surfaces of sludge flocs, hydrolysis of triacylglyceride by lipases and the uptake of long-chain fatty acid by bacteria under various conditions. The model can be helpful to structure design and evaluation of activated sludge experiment with lipids.

Application of Image Analysis System for Study of Activated Sludge Flocs

1986 ◽  
Vol 21 (1) ◽  
pp. 130-140 ◽  
Author(s):  
Da-hong Li ◽  
J. J. Ganczarczyk
Keyword(s):  
Image Analysis ◽  
Activated Sludge ◽  
Statistical Processing ◽  
Equivalent Diameter ◽  
Image Analysis System ◽  
Sectional Area ◽  
Cross Sectional ◽  
Computerized Image Analysis ◽  
Sludge Flocs ◽  
Analysis System

Abstract The computerized image analysis system has been successfully used for determination and statistical processing of the following geometric characteristics of activated sludge flocs: longest dimension, breadth, equivalent diameter, cross-sectional area, perimeter, elongation, and circularity. These parameters could be effectively and precisely determined by the system applied. In addition, the studied method, as compared to direct microscope observation and photography floc-sizing methods, was found to be more accurate, less time-consuming, and less dependent on the investigators.

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