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Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge.

Wang T, Zhang D, Dai L, Chen Y, Dai X - Sci Rep (2016)

Bottom Line: This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS).The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively).These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them.

View Article: PubMed Central - PubMed

Affiliation: State key laboratory of pollution control and Resources reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.

ABSTRACT
Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them.

No MeSH data available.


Scanning electron micrograph (SEM) images (a2–e2, a3–e3) and energy-dispersive X-ray (EDX) analysis (a1–e1) of anaerobic granular sludge in the reactors exposed to Ag NPs, MgO NPs, nZVI and Fe2O3 NPs at the indicated concentrations.Control (a1–a3), Ag NPs-500 (b1–b3), MgO NPs-500 (c1–c3), nZVI-10 (d1–d3), Fe2O3 NPs-100 (e1–e3).
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f3: Scanning electron micrograph (SEM) images (a2–e2, a3–e3) and energy-dispersive X-ray (EDX) analysis (a1–e1) of anaerobic granular sludge in the reactors exposed to Ag NPs, MgO NPs, nZVI and Fe2O3 NPs at the indicated concentrations.Control (a1–a3), Ag NPs-500 (b1–b3), MgO NPs-500 (c1–c3), nZVI-10 (d1–d3), Fe2O3 NPs-100 (e1–e3).

Mentions: As shown in Fig. 3, the anaerobic granular sludge (AGS) surfaces were rougher in the reactors exposed to different concentrations of Ag NPs, MgO NPs, nZVI and Fe2O3 NPs (nZVI-10, Ag NPs-100, Fe2O3 NPs-100, Ag NPs-500, and MgO NPs-500) than in the control. The SEM and EDX analyses showed that many NPs were adsorbed onto the AGS surfaces after long-term exposure to the NPs. The combination of NPs and AGS was primarily due to electrostatic interactions and the high specific area of the NPs1. The cell membrane integrity of the activated sludge was measured by a Lactate dehydrogenase (LDH) release assay. As shown in Fig. S1 (Supplementary Information), the results of the LDH release assays indicated that the contents of lactate dehydrogenase, which is a cell-membrane damage marker, in the reactors exposed to 500 mg/g TSS Ag NPs or 500 mg/g TSS MgO NPs were considerably higher than those in the reactors exposed to 10 mg/g TSS nZVI or 100 mg/g TSS Fe2O3 NPs, suggesting that high concentrations of Ag NPs or MgO NPs could damage cell membranes.


Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge.

Wang T, Zhang D, Dai L, Chen Y, Dai X - Sci Rep (2016)

Scanning electron micrograph (SEM) images (a2–e2, a3–e3) and energy-dispersive X-ray (EDX) analysis (a1–e1) of anaerobic granular sludge in the reactors exposed to Ag NPs, MgO NPs, nZVI and Fe2O3 NPs at the indicated concentrations.Control (a1–a3), Ag NPs-500 (b1–b3), MgO NPs-500 (c1–c3), nZVI-10 (d1–d3), Fe2O3 NPs-100 (e1–e3).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4863170&req=5

f3: Scanning electron micrograph (SEM) images (a2–e2, a3–e3) and energy-dispersive X-ray (EDX) analysis (a1–e1) of anaerobic granular sludge in the reactors exposed to Ag NPs, MgO NPs, nZVI and Fe2O3 NPs at the indicated concentrations.Control (a1–a3), Ag NPs-500 (b1–b3), MgO NPs-500 (c1–c3), nZVI-10 (d1–d3), Fe2O3 NPs-100 (e1–e3).
Mentions: As shown in Fig. 3, the anaerobic granular sludge (AGS) surfaces were rougher in the reactors exposed to different concentrations of Ag NPs, MgO NPs, nZVI and Fe2O3 NPs (nZVI-10, Ag NPs-100, Fe2O3 NPs-100, Ag NPs-500, and MgO NPs-500) than in the control. The SEM and EDX analyses showed that many NPs were adsorbed onto the AGS surfaces after long-term exposure to the NPs. The combination of NPs and AGS was primarily due to electrostatic interactions and the high specific area of the NPs1. The cell membrane integrity of the activated sludge was measured by a Lactate dehydrogenase (LDH) release assay. As shown in Fig. S1 (Supplementary Information), the results of the LDH release assays indicated that the contents of lactate dehydrogenase, which is a cell-membrane damage marker, in the reactors exposed to 500 mg/g TSS Ag NPs or 500 mg/g TSS MgO NPs were considerably higher than those in the reactors exposed to 10 mg/g TSS nZVI or 100 mg/g TSS Fe2O3 NPs, suggesting that high concentrations of Ag NPs or MgO NPs could damage cell membranes.

Bottom Line: This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS).The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively).These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them.

View Article: PubMed Central - PubMed

Affiliation: State key laboratory of pollution control and Resources reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.

ABSTRACT
Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them.

No MeSH data available.