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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.


Related in: MedlinePlus

Concentration of TOCd in sorption tests with azide-inhibited (A) and live activated sludge (B).The solid lines show fits using 1st-order kinetics for the measurements points between 1 min and 60 min. Two repeated tests were carried out with each type of sludge.
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pone.0119371.g005: Concentration of TOCd in sorption tests with azide-inhibited (A) and live activated sludge (B).The solid lines show fits using 1st-order kinetics for the measurements points between 1 min and 60 min. Two repeated tests were carried out with each type of sludge.

Mentions: The rate of biosorption of dissolved organics was compared with live and azide-inhibited activated sludge. Azide treatment resulted in some release of organic substances by the sludge, ranging from 2.5 to 3.0 mgTOCd/gVSS in the two tests. This is shown by the higher starting concentrations of TOCd in the sorption tests with azide-inhibited sludge (Fig. 5A) compared to live activated sludge (Fig. 5B). However, both live and azide-inhibited sludge showed a near-instantaneous sorption event upon mixing with raw wastewater. The extent of near-instantaneous sorption was 2.0–2.1 mgTOCd/gVSS for live activated sludge and 1.0–1.3 mgTOCd/gVSS for azide-inhibited sludge. The rate of removal was 24–36 mgTOCd/gVSS∙d for live activated sludge and 30–48 mgTOCd/gVSS∙d for azide-inhibited sludge. First-order kinetics could be used to describe the data with kinetic coefficients of 0.014–0.020 L/gVSS∙d for both the live and azide-inhibited sludge (Table 2). However, using zero-order reaction rates provided equally good fits and the rates of removal shown above were calculated from the linear decrease in TOCd concentrations.


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)

Concentration of TOCd in sorption tests with azide-inhibited (A) and live activated sludge (B).The solid lines show fits using 1st-order kinetics for the measurements points between 1 min and 60 min. Two repeated tests were carried out with each type of sludge.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0119371.g005: Concentration of TOCd in sorption tests with azide-inhibited (A) and live activated sludge (B).The solid lines show fits using 1st-order kinetics for the measurements points between 1 min and 60 min. Two repeated tests were carried out with each type of sludge.
Mentions: The rate of biosorption of dissolved organics was compared with live and azide-inhibited activated sludge. Azide treatment resulted in some release of organic substances by the sludge, ranging from 2.5 to 3.0 mgTOCd/gVSS in the two tests. This is shown by the higher starting concentrations of TOCd in the sorption tests with azide-inhibited sludge (Fig. 5A) compared to live activated sludge (Fig. 5B). However, both live and azide-inhibited sludge showed a near-instantaneous sorption event upon mixing with raw wastewater. The extent of near-instantaneous sorption was 2.0–2.1 mgTOCd/gVSS for live activated sludge and 1.0–1.3 mgTOCd/gVSS for azide-inhibited sludge. The rate of removal was 24–36 mgTOCd/gVSS∙d for live activated sludge and 30–48 mgTOCd/gVSS∙d for azide-inhibited sludge. First-order kinetics could be used to describe the data with kinetic coefficients of 0.014–0.020 L/gVSS∙d for both the live and azide-inhibited sludge (Table 2). However, using zero-order reaction rates provided equally good fits and the rates of removal shown above were calculated from the linear decrease in TOCd concentrations.

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.


Related in: MedlinePlus