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Molten-Salt Synthesis of Complex Metal Oxide Nanoparticles
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Biodegradation of metal-[S,S]-EDDS complexes
P C Vandevivere1, H Saveyn, W Verstraete
1Laboratory of Microbial Ecology and Technology, Department of Biological and Applied Sciences, University of Gent, Coupure L 653, 9000 Gent, Belgium.
Environmental Science & Technology
|May 18, 2001
Summary
Ethylenediaminedisuccinic acid (EDDS) metal complexes show variable biodegradability. While Ca-, Fe-, and Pb-EDDS readily degrade, Cu- and Ni-EDDS are recalcitrant, with degradation influenced by free EDDS concentration and metal toxicity.
Area of Science:
- Environmental Chemistry
- Environmental Microbiology
- Biotechnology
Background:
- Ethylenediaminedisuccinic acid (EDDS) is a biodegradable metal chelating agent used in consumer products.
- The biodegradability of metal-EDDS complexes is not well-documented, posing potential environmental concerns.
Purpose of the Study:
- To investigate the biodegradability of various metal-EDDS complexes using activated sludge.
- To determine the factors influencing the biodegradation of metal-EDDS complexes.
Main Methods:
- Activated sludge was used as the microbial source, with EDDS as the sole carbon and nitrogen source.
- Biodegradation of 1 mM pulses of different metal-EDDS complexes was assessed.
- Speciation analysis was performed to determine free EDDS concentrations.
- A Monod-type model was developed to describe degradation rates.
Main Results:
- Ca-, Cr(III)-, Fe(III)-, Pb-, Al-, Cd-, Mg-, and Na-EDDS were readily biodegraded, with ZnEDDS showing a lag phase.
- Cu-, Ni-, and Co-EDDS complexes were not significantly degraded.
- HgEDDS biodegradation was inhibited by metal toxicity.
- Biodegradation correlated with free EDDS concentration (>10(-5.4) M for biodegradable complexes).
- A Monod model with EDDS3- as substrate (K(s) ≈ 10(-6) M) explained degradation rates.
- Aerated biofilters removed 10 mM Pb- or ZnEDDS at 0.4 mM/h.
Conclusions:
- The biodegradability of metal-EDDS complexes is metal-dependent.
- Free EDDS concentration is a critical factor for biodegradation.
- The Monod model effectively predicts metal-EDDS degradation rates.
- Engineered biofilters can efficiently remove certain metal-EDDS complexes from wastewater.
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