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Sorption and release of organics by primary, anaerobic, and aerobic activated sludge mixed with raw municipal wastewater.

Modin O, Saheb Alam S, Persson F, Wilén BM - PLoS ONE (2015)

Bottom Line: This study compared primary-, anaerobic-, and aerobic activated sludge as sorbents, determined sorption capacity and kinetics, and investigated some characteristics of the organics being sorbed.The 5-min sorption capacity of activated sludge was 6.5±10.8 mg total organic carbon (TOC) per g volatile suspend solids (VSS) for particulate organics and 5.0±4.7 mgTOC/gVSS for dissolved organics.The observed instantaneous sorption appeared to be mainly due to organics larger than 20 kDa in size being sorbed, although molecules with a size of about 200 Da with strong UV absorbance at 215-230 nm were also rapidly removed.

View Article: PubMed Central - PubMed

Affiliation: Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden.

ABSTRACT
New activated sludge processes that utilize sorption as a major mechanism for organics removal are being developed to maximize energy recovery from wastewater organics, or as enhanced primary treatment technologies. To model and optimize sorption-based activated sludge processes, further knowledge about sorption of organics onto sludge is needed. This study compared primary-, anaerobic-, and aerobic activated sludge as sorbents, determined sorption capacity and kinetics, and investigated some characteristics of the organics being sorbed. Batch sorption assays were carried out without aeration at a mixing velocity of 200 rpm. Only aerobic activated sludge showed net sorption of organics. Sorption of dissolved organics occurred by a near-instantaneous sorption event followed by a slower process that obeyed 1st order kinetics. Sorption of particulates also followed 1st order kinetics but there was no instantaneous sorption event; instead there was a release of particles upon mixing. The 5-min sorption capacity of activated sludge was 6.5±10.8 mg total organic carbon (TOC) per g volatile suspend solids (VSS) for particulate organics and 5.0±4.7 mgTOC/gVSS for dissolved organics. The observed instantaneous sorption appeared to be mainly due to organics larger than 20 kDa in size being sorbed, although molecules with a size of about 200 Da with strong UV absorbance at 215-230 nm were also rapidly removed.

No MeSH data available.


Removal of TSS and TOCd in kinetic tests carried out on two different sampling occasions.The legends show addition of activated sludge in gVSS per litre. Control samples (Ctrl) did not contain added activated sludge. Symbols show measured data whereas lines were fitted using Equation 2. Each measurement point is the average of two replicate tests with the error bars representing the individual measurements.
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pone.0119371.g004: Removal of TSS and TOCd in kinetic tests carried out on two different sampling occasions.The legends show addition of activated sludge in gVSS per litre. Control samples (Ctrl) did not contain added activated sludge. Symbols show measured data whereas lines were fitted using Equation 2. Each measurement point is the average of two replicate tests with the error bars representing the individual measurements.

Mentions: The sorption kinetics was investigated with raw wastewater and aerobic activated sludge collected on two different days. The changes in concentrations of TSS and TOCd are shown in Fig. 4 while kinetic coefficients and R2-values for the fits are shown in Table 2. Upon mixing wastewater and sludge, an instantaneous increase in TSS concentration and decrease in TOCd concentration can be observed. The increase in TSS can be explained by release of small particles by the sludge. The decrease in TOCd suggests an instantaneous sorption of TOCd from the wastewater onto the sludge. Following this instantaneous sorption or release, sorption of both TSS and TOCd obeys 1st order kinetics.


Sorption and release of organics by primary, anaerobic, and aerobic activated sludge mixed with raw municipal wastewater.

Modin O, Saheb Alam S, Persson F, Wilén BM - PLoS ONE (2015)

Removal of TSS and TOCd in kinetic tests carried out on two different sampling occasions.The legends show addition of activated sludge in gVSS per litre. Control samples (Ctrl) did not contain added activated sludge. Symbols show measured data whereas lines were fitted using Equation 2. Each measurement point is the average of two replicate tests with the error bars representing the individual measurements.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4359093&req=5

pone.0119371.g004: Removal of TSS and TOCd in kinetic tests carried out on two different sampling occasions.The legends show addition of activated sludge in gVSS per litre. Control samples (Ctrl) did not contain added activated sludge. Symbols show measured data whereas lines were fitted using Equation 2. Each measurement point is the average of two replicate tests with the error bars representing the individual measurements.
Mentions: The sorption kinetics was investigated with raw wastewater and aerobic activated sludge collected on two different days. The changes in concentrations of TSS and TOCd are shown in Fig. 4 while kinetic coefficients and R2-values for the fits are shown in Table 2. Upon mixing wastewater and sludge, an instantaneous increase in TSS concentration and decrease in TOCd concentration can be observed. The increase in TSS can be explained by release of small particles by the sludge. The decrease in TOCd suggests an instantaneous sorption of TOCd from the wastewater onto the sludge. Following this instantaneous sorption or release, sorption of both TSS and TOCd obeys 1st order kinetics.

Bottom Line: This study compared primary-, anaerobic-, and aerobic activated sludge as sorbents, determined sorption capacity and kinetics, and investigated some characteristics of the organics being sorbed.The 5-min sorption capacity of activated sludge was 6.5±10.8 mg total organic carbon (TOC) per g volatile suspend solids (VSS) for particulate organics and 5.0±4.7 mgTOC/gVSS for dissolved organics.The observed instantaneous sorption appeared to be mainly due to organics larger than 20 kDa in size being sorbed, although molecules with a size of about 200 Da with strong UV absorbance at 215-230 nm were also rapidly removed.

View Article: PubMed Central - PubMed

Affiliation: Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden.

ABSTRACT
New activated sludge processes that utilize sorption as a major mechanism for organics removal are being developed to maximize energy recovery from wastewater organics, or as enhanced primary treatment technologies. To model and optimize sorption-based activated sludge processes, further knowledge about sorption of organics onto sludge is needed. This study compared primary-, anaerobic-, and aerobic activated sludge as sorbents, determined sorption capacity and kinetics, and investigated some characteristics of the organics being sorbed. Batch sorption assays were carried out without aeration at a mixing velocity of 200 rpm. Only aerobic activated sludge showed net sorption of organics. Sorption of dissolved organics occurred by a near-instantaneous sorption event followed by a slower process that obeyed 1st order kinetics. Sorption of particulates also followed 1st order kinetics but there was no instantaneous sorption event; instead there was a release of particles upon mixing. The 5-min sorption capacity of activated sludge was 6.5±10.8 mg total organic carbon (TOC) per g volatile suspend solids (VSS) for particulate organics and 5.0±4.7 mgTOC/gVSS for dissolved organics. The observed instantaneous sorption appeared to be mainly due to organics larger than 20 kDa in size being sorbed, although molecules with a size of about 200 Da with strong UV absorbance at 215-230 nm were also rapidly removed.

No MeSH data available.