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Published on: December 19, 2017
Behaviour of heavy metals during tertiary bio-filtration
V Miska1, K Gorter, H W H Menkveld
1Department of Sanitary Engineering, Faculty of Civil Engineering and Geoscience, Delft University of Technology, P.O. Box 5048, 2600 GA Delft, The Netherlands. v.miska@citg.tudelft.nl
Summary
Stringent water quality standards necessitate effective heavy metal removal. This study demonstrates that denitrifying flocculation filtration, enhanced with activated carbon, effectively removes copper, nickel, and zinc from wastewater treatment plant effluent.
Area of Science:
- Environmental Science
- Water Treatment Engineering
- Analytical Chemistry
Background:
- European Water Framework Directive 2000/60/EC mandates stricter water quality.
- The Netherlands introduced Maximum Tolerable Risk (MTR) values for pollutants.
- Wastewater treatment plants (WWTPs) face challenges in meeting nutrient and heavy metal limits.
Purpose of the Study:
- To investigate heavy metal (HM) removal efficiency in a Dutch WWTP effluent.
- To evaluate the effectiveness of denitrifying flocculation filtration with powdered activated carbon (PAC).
- To assess the removal of copper, nickel, and zinc under simulated conditions.
Main Methods:
- Dosing a mixture of copper, nickel, and zinc chloride to WWTP effluent.
- Conducting preliminary jar tests with PAC.
- Performing pilot-scale and lab-scale filtration tests with media filtration and activated carbon filters.
Main Results:
- High removal rates for nickel and zinc observed during jar tests with PAC.
- Significant removal of the bounded fraction of copper and zinc in pilot-scale filtration.
- Complete removal of all three heavy metals achieved in the lab-scale activated carbon filter.
- Nickel, initially dissolved, was effectively removed by the activated carbon filter.
Conclusions:
- Denitrifying flocculation filtration, especially with activated carbon, is effective for heavy metal removal.
- Adsorption onto activated carbon plays a key role in HM removal.
- Further discussion on HM toxicity and bioavailability is warranted following effective removal.
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