Nanoparticles within WWTP sludges have minimal impact on leachate quality and soil microbial community structure and function

Summary

One of the main pathways by which engineered nanoparticles (ENPs) enter the environment is through land application of waste water treatment plant (WWTP) sewage sludges. WWTP sludges, enriched with Ag and ZnO ENPs or their corresponding soluble metal salts during anaerobic digestion and subsequently mixed with soil (targeting a final concentration of 1400 and 140 mg/kg for Zn and Ag, respectively), were subjected to 6 months of ageing and leaching in lysimeter columns outdoors. Amounts of Zn and Ag leached were very low, accounting for <0.3% and <1.4% of the total Zn and Ag, respectively. No differences in total leaching rates were observed between treatments of Zn or Ag originally input to WWTP as ENP or salt forms. Phospholipid fatty acid profiling indicated a reduction in the fungal com