The impact of zinc oxide nanoparticles on nitrification and the bacterial community in activated sludge in an SBR

Abstract

Zinc oxide (ZnO) nanoparticles (NPs) have been reported to induce adverse effects on organisms. The impacts of ZnO NPs on nitrification and the nitrobacteria community in activated sludge were investigated in a simulated SBR. It revealed that ZnO NPs at low concentrations (5 and 10 mg L À1 ) slightly inhibited nitrification. At these concentrations the activity of ammonia monooxygenase (AMO) and nitrite oxidoreductase (NOR) as well as the cell membrane integrity of Nitrosomonas europaea were almost unaffected. Concentrations of 20 mg L À1 and 50 mg L À1 ZnO NPs had significantly adverse effects on the activity of AMO and NOR and on the transformation of NH 4 + -N to NO 2 À -N and NO 2 À -N to NO 3 À -N. Analysis by denaturing gradient gel electrophoresis (DGGE) revealed that higher concentrations of ZnONPs significantly inhibited the growth of the typical ammonia-oxidizing bacteria (AOB) that were mainly responsible for oxidation of ammonia to nitrate. Moderate concentrations of ZnO NPs could accelerate the growth of some types of denitrifying bacteria and promote the growth of some pathogenic bacteria.Moderate and high concentrations of ZnO NPs could obviously destroy the integrity of the cell membrane of Nitrosomonas europaea. These findings meaningfully assessed the adverse effects of ZnO NPs on activated sludge in wastewater treatment.

Evaluation of performance and microbial community successional patterns in an integrated OCO reactor under ZnO nanoparticle stress

“…These results coincided with previous studies which proved that ammonia removal is inhibited by inhibition of the respiration of nitrifying bacteria 21 or enzyme activity. 22 For phosphorus removal, TP removal rate was kept above 90% in phases P0, P1 and P2 (Fig. 3).…”

Occurrence and removal of engineered nanoparticles in drinking water treatment and wastewater treatment processes: A review

“…Most NPs aggregate at the wastewater bottom and then attach to the biomass. Most of the Ag-NPs can remain in sulfate and inorganic wastewater treatment plants and can be extracted from the plant surfaces [69]. Moreover, in effluents and sludge, most polysaccharide NPs are present in the form of Ag 2 S. Ag-NPs are transported to sewers with a relatively minor impact on the biofilm transport capacity.…”

Influences of magnetic powder addition on the anaerobic digestion of municipal dewatered sludge

“…Knowledge in terms of specific intensity level that is suitable to promote the growth of bacteria/microorganisms is still limited. As the anaerobic digestion bacteria play a vital role in the anaerobic digestion treatment processes and different bacterium has its unique susceptibility level to the magnetic field intensity [18,26], research about the influence of magnetic field intensity on anaerobic digestion bacteria or aerobic bacteria should be further required. Figure 3 indicates that methane content is much higher under the conditions with bacteria than that without bacteria, although the total gas outputs under the two conditions are nearly the same.…”

“…As the permanent magnetic material has the advantages of one‐time investment , recyclability and strong magnetism , new low‐energy consumption technologies, such as the magnetic effect method, have been developed for sludge dewatering , organic matter degradation , and nitrogen removal in recent years, and these applications exhibit good performances. As microorganisms play an important role in sludge anaerobic digestion, magnetic effects combined with microbial technology for sludge anaerobic digestion is worth investigating.…”