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Nonoxidative removal of organics in the activated sludge process.

Modin O, Persson F, Wilén BM, Hermansson M - Crit Rev Environ Sci Technol (2016)

Bottom Line: Sorption onto activated sludge can remove a large fraction of the colloidal and particulate wastewater organics.Intracellular storage of, e.g., polyhydroxyalkanoates (PHA), triacylglycerides (TAG), or wax esters can convert wastewater organics into precursors for high-value products.Better utilization of nonoxidative processes in activated sludge could reduce the wasteful aerobic oxidation of organic compounds and lead to more resource-efficient wastewater treatment plants.

View Article: PubMed Central - PubMed

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

ABSTRACT

The activated sludge process is commonly used to treat wastewater by aerobic oxidation of organic pollutants into carbon dioxide and water. However, several nonoxidative mechanisms can also contribute to removal of organics. Sorption onto activated sludge can remove a large fraction of the colloidal and particulate wastewater organics. Intracellular storage of, e.g., polyhydroxyalkanoates (PHA), triacylglycerides (TAG), or wax esters can convert wastewater organics into precursors for high-value products. Recently, several environmental, economic, and technological drivers have stimulated research on nonoxidative removal of organics for wastewater treatment. In this paper, we review these nonoxidative removal mechanisms as well as the existing and emerging process configurations that make use of them for wastewater treatment. Better utilization of nonoxidative processes in activated sludge could reduce the wasteful aerobic oxidation of organic compounds and lead to more resource-efficient wastewater treatment plants.

No MeSH data available.


Plot of nonsorbable organics concentration (a) and organic loading (F/M) from five studies. Note that data from Jorand et al. (1995) and Modin et al. (2015) was converted from TOC to COD assuming 2.7 gCOD/gTOC and that concentrations from those studies refer to organics smaller than 0.45 μm, concentrations from Guellil et al. (2001) and La Motta et al. (2004) refer to the nonsettleable fraction, and concentrations from Jimenez et al. (2005) refer to nonsettleable organics larger than 0.001 µm.
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f0003: Plot of nonsorbable organics concentration (a) and organic loading (F/M) from five studies. Note that data from Jorand et al. (1995) and Modin et al. (2015) was converted from TOC to COD assuming 2.7 gCOD/gTOC and that concentrations from those studies refer to organics smaller than 0.45 μm, concentrations from Guellil et al. (2001) and La Motta et al. (2004) refer to the nonsettleable fraction, and concentrations from Jimenez et al. (2005) refer to nonsettleable organics larger than 0.001 µm.

Mentions: The sorption rate coefficient, k, and the nonsorbable organics concentration, a, determined by different workers are summarized in Table 3. The sorption rate constant appears to be in the order of 10−4 L/mg·min. In general, sorption of larger particles is faster than sorption of smaller particles. The concentration of nonsorbable organics varies but appears to depend on loading. Figure 3 shows a positive correlation between organic loading and nonsorbable organics concentration based on data compiled from several studies. Temperature differences in the range 4–33°C has been shown to have very little effect on sorption kinetics by activated sludge (Tsezos and Wang, 1991; Jorand et al., 1995). Sorption kinetics is usually not considered in activated sludge models. However, La Motta et al. (2007a) included kinetic expression in a mathematical model for the preliminary design of activated sludge systems (La Motta et al., 2007a, 2007b).Table 3.


Nonoxidative removal of organics in the activated sludge process.

Modin O, Persson F, Wilén BM, Hermansson M - Crit Rev Environ Sci Technol (2016)

Plot of nonsorbable organics concentration (a) and organic loading (F/M) from five studies. Note that data from Jorand et al. (1995) and Modin et al. (2015) was converted from TOC to COD assuming 2.7 gCOD/gTOC and that concentrations from those studies refer to organics smaller than 0.45 μm, concentrations from Guellil et al. (2001) and La Motta et al. (2004) refer to the nonsettleable fraction, and concentrations from Jimenez et al. (2005) refer to nonsettleable organics larger than 0.001 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4940897&req=5

f0003: Plot of nonsorbable organics concentration (a) and organic loading (F/M) from five studies. Note that data from Jorand et al. (1995) and Modin et al. (2015) was converted from TOC to COD assuming 2.7 gCOD/gTOC and that concentrations from those studies refer to organics smaller than 0.45 μm, concentrations from Guellil et al. (2001) and La Motta et al. (2004) refer to the nonsettleable fraction, and concentrations from Jimenez et al. (2005) refer to nonsettleable organics larger than 0.001 µm.
Mentions: The sorption rate coefficient, k, and the nonsorbable organics concentration, a, determined by different workers are summarized in Table 3. The sorption rate constant appears to be in the order of 10−4 L/mg·min. In general, sorption of larger particles is faster than sorption of smaller particles. The concentration of nonsorbable organics varies but appears to depend on loading. Figure 3 shows a positive correlation between organic loading and nonsorbable organics concentration based on data compiled from several studies. Temperature differences in the range 4–33°C has been shown to have very little effect on sorption kinetics by activated sludge (Tsezos and Wang, 1991; Jorand et al., 1995). Sorption kinetics is usually not considered in activated sludge models. However, La Motta et al. (2007a) included kinetic expression in a mathematical model for the preliminary design of activated sludge systems (La Motta et al., 2007a, 2007b).Table 3.

Bottom Line: Sorption onto activated sludge can remove a large fraction of the colloidal and particulate wastewater organics.Intracellular storage of, e.g., polyhydroxyalkanoates (PHA), triacylglycerides (TAG), or wax esters can convert wastewater organics into precursors for high-value products.Better utilization of nonoxidative processes in activated sludge could reduce the wasteful aerobic oxidation of organic compounds and lead to more resource-efficient wastewater treatment plants.

View Article: PubMed Central - PubMed

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

ABSTRACT

The activated sludge process is commonly used to treat wastewater by aerobic oxidation of organic pollutants into carbon dioxide and water. However, several nonoxidative mechanisms can also contribute to removal of organics. Sorption onto activated sludge can remove a large fraction of the colloidal and particulate wastewater organics. Intracellular storage of, e.g., polyhydroxyalkanoates (PHA), triacylglycerides (TAG), or wax esters can convert wastewater organics into precursors for high-value products. Recently, several environmental, economic, and technological drivers have stimulated research on nonoxidative removal of organics for wastewater treatment. In this paper, we review these nonoxidative removal mechanisms as well as the existing and emerging process configurations that make use of them for wastewater treatment. Better utilization of nonoxidative processes in activated sludge could reduce the wasteful aerobic oxidation of organic compounds and lead to more resource-efficient wastewater treatment plants.

No MeSH data available.