title: Insights into the effect of mixed engineered nanoparticles on activated sludge performance.
abstract: In this study, the effects, fate and transport of ENPs in wastewater treatment plants (WWTP) were investigated using three parallel pilot WWTPs operated under identical conditions. The WWTPs were spiked with (i) an ENP mixture consisting of silver oxide, titanium dioxide and zinc oxide, and (ii) bulk metal salts. The third plant served as control (unspiked). ENP effects were evaluated for (i) bulk contaminant removal, (ii) activated sludge (AS) process performance, (iii) microbial community structure and dynamics and (iv) microbial inhibition. ENPs showed a strong affinity for biosolids and induced a specific oxygen uptake rate two times higher than the control. The heterotrophic biomass retained its ability to nitrify and degrade organic matter. However, non-recovery of ammonia- and nitrite-oxidizing bacteria such as Nitrosomonas, Nitrobacter or Nitrospira in the ENP spiked reactors suggests selective inhibitory effects. The results further suggest that ENPs and metal salts have antimicrobial properties which can reduce synthesis of extracellular polymeric substances and therefore floc formation. Scanning electron microscopy evidenced selective damage to some microbes, whereas lipid fingerprinting and 454 pyrosequencing indicated a temporal shift in the microbial community structure and diversity. Acidovorax, Rhodoferax, Comamonas and Methanosarcina were identified as nano-tolerant species. Competitive growth advantage of the nano-tolerant species influenced the removal processes and unlike other xenobiotic compounds, ENPs can hasten the natural selection of microbial species in AS.
authors.affiliation: School of Energy, Environment and Agrifood, Cranfield University, College Road, Cranfield, Bedfordshire MK43 0AL, UK.
authors.forename: Samuel
authors.initials: S
authors.lastname: Eduok
authors.affiliation: School of Energy, Environment and Agrifood, Cranfield University, College Road, Cranfield, Bedfordshire MK43 0AL, UK.
authors.forename: Callum
authors.initials: C
authors.lastname: Hendry
authors.affiliation: School of Energy, Environment and Agrifood, Cranfield University, College Road, Cranfield, Bedfordshire MK43 0AL, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Ferguson
authors.affiliation: School of Energy, Environment and Agrifood, Cranfield University, College Road, Cranfield, Bedfordshire MK43 0AL, UK.
authors.forename: Ben
authors.initials: B
authors.lastname: Martin
authors.affiliation: School of Energy, Environment and Agrifood, Cranfield University, College Road, Cranfield, Bedfordshire MK43 0AL, UK.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Villa
authors.affiliation: School of Energy, Environment and Agrifood, Cranfield University, College Road, Cranfield, Bedfordshire MK43 0AL, UK.
authors.forename: Bruce
authors.initials: B
authors.lastname: Jefferson
authors.affiliation: School of Energy, Environment and Agrifood, Cranfield University, College Road, Cranfield, Bedfordshire MK43 0AL, UK f.coulon@cranfield.ac.uk.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Coulon
mesh_terms: D000641:Ammonia / Q000378:metabolism; D018533:Biomass; D020585:Comamonas / Q000378:metabolism*; D052836:Heterotrophic Processes; D017020:Methanosarcina / Q000378:metabolism*; D053758:Nanoparticles; D058465:Nitrification; D009573:Nitrites / Q000378:metabolism; D009576:Nitrobacter / Q000302:isolation & purification; D009606:Nitrosomonas / Q000302:isolation & purification; D010087:Oxides / Q000737:chemistry; D010100:Oxygen / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*; D018030:Silver Compounds / Q000737:chemistry; D014025:Titanium / Q000737:chemistry; D018508:Water Purification / Q000379:methods*; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D009573:Nitrites; D010087:Oxides; D012722:Sewage; D018030:Silver Compounds; C009495:titanium dioxide; D000641:Ammonia; C040225:disilver oxide; D014025:Titanium; D010100:Oxygen; D015034:Zinc Oxide
keywords: activated sludge; engineered nanoparticles; nano-tolerant microbial species