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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.


Schematic of a conventional activated sludge wastewater treatment plant.
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f0001: Schematic of a conventional activated sludge wastewater treatment plant.

Mentions: The activated sludge process is common in wastewater treatment plants. It was developed over 100 years ago (Arden and Lockett, 1914) and is primarily used for removal of biodegradable organic compounds, which could otherwise cause oxygen depletion of receiving waters if discharged in the treatment plant effluent. Certain process configurations also allow simultaneous biological removal of nitrogen and phosphorous from the wastewater (Tchobanoglous et al., 2004). A typical process configuration for an activated sludge plant is depicted in Figure 1. The activated sludge comes in contact with the presettled wastewater in an aerated tank. Live microorganisms present in the sludge oxidize the organics into carbon dioxide and water. The oxidation is coupled to microbial growth by which the microorganisms assimilate a fraction of the organics. The activated sludge is separated from the treated water in a settling tank. Alternatively, a membrane bioreactor (MBR) can be used to separate the treated effluent using membrane filtration (Yamamoto et al., 1989). A portion of the sludge corresponding to the net amount of microbial growth in the system is wasted while the rest is returned to the inlet of the aerated tank. The wasted sludge is often converted into biogas in an anaerobic digester.Figure 1.


Nonoxidative removal of organics in the activated sludge process.

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

Schematic of a conventional activated sludge wastewater treatment plant.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f0001: Schematic of a conventional activated sludge wastewater treatment plant.
Mentions: The activated sludge process is common in wastewater treatment plants. It was developed over 100 years ago (Arden and Lockett, 1914) and is primarily used for removal of biodegradable organic compounds, which could otherwise cause oxygen depletion of receiving waters if discharged in the treatment plant effluent. Certain process configurations also allow simultaneous biological removal of nitrogen and phosphorous from the wastewater (Tchobanoglous et al., 2004). A typical process configuration for an activated sludge plant is depicted in Figure 1. The activated sludge comes in contact with the presettled wastewater in an aerated tank. Live microorganisms present in the sludge oxidize the organics into carbon dioxide and water. The oxidation is coupled to microbial growth by which the microorganisms assimilate a fraction of the organics. The activated sludge is separated from the treated water in a settling tank. Alternatively, a membrane bioreactor (MBR) can be used to separate the treated effluent using membrane filtration (Yamamoto et al., 1989). A portion of the sludge corresponding to the net amount of microbial growth in the system is wasted while the rest is returned to the inlet of the aerated tank. The wasted sludge is often converted into biogas in an anaerobic digester.Figure 1.

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.