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Published on: June 21, 2015
Removal characteristics of engineered nanoparticles by activated sludge
Hee-Jin Park1, Hee Yeon Kim, Seoeun Cha
1World Class University (WCU) Program of Chemical Convergence for Energy & Environment (C2E2), School of Chemical and Biological Engineering, College of Engineering, Institute of Chemical Process, Seoul National University (SNU), Daehak-dong, Gwanak-gu, Seoul 151-744, Republic of Korea.
Engineered nanoparticles (NPs) are increasingly released into the environment. Activated sludge effectively removes NPs, with removal rates influenced by NP properties, sewage chemistry, and extracellular polymeric substances (EPS).
Area of Science:
- Environmental Science
- Nanotechnology
- Environmental Engineering
Background:
- Engineered nanoparticles (NPs) are prevalent in commercial products, leading to increased environmental release.
- The fate of NPs during sewage treatment is critical for understanding their environmental pathways.
- Activated sludge processes are a key stage in wastewater treatment where NP removal occurs.
Purpose of the Study:
- To investigate the removal of engineered NPs (silver, titanium dioxide, and silicon dioxide) using activated sludge.
- To evaluate the influence of NP physicochemical properties, contact time, sewage chemistry, and extracellular polymeric substances (EPS) on NP removal.
- To understand the mechanisms behind NP removal in activated sludge systems.
Main Methods:
- Testing the removal of silver NPs (AgNPs), TiO2 NPs, and SiO2 NPs using activated sludge.
- Evaluating the impact of NP properties (hydrodynamic diameter, zeta potential), contact time, ionic compounds, and EPS.
- Analyzing NP removal efficiencies under various simulated sewage conditions.
Main Results:
- Significant time-dependent removal of all tested NPs by activated sludge was observed.
- Removal efficiencies varied by NP type and were linked to NP stability (hydrodynamic diameter and zeta potential).
- Ionic compounds and EPS substantially enhanced NP removal, indicating NP instability and entrapment mechanisms.
Conclusions:
- Activated sludge can effectively remove engineered NPs, but efficiency depends on NP characteristics and wastewater conditions.
- NP instability in sewage (due to ionic strength) and entrapment by EPS are key removal mechanisms.
- Optimizing activated sludge process conditions and considering sludge characteristics are crucial for effective NP removal from wastewater.
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