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'Active' filters for upgrading phosphorus removal from pond systems.
1The Centre for Environmental Technology and Engineering, Institute of Technology and Engineering, Massey University, Private Bag 11222, Palmerston North, New Zealand.
Summary
Limestone and iron slag filters effectively remove phosphorus from wastewater. Field results differed significantly from lab tests, with iron slag performing better in the field and limestone in the lab.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
Background:
- Phosphorus discharge from wastewater treatment ponds contributes to eutrophication.
- Upgrading existing treatment systems is crucial for effective nutrient management.
Purpose of the Study:
- To evaluate limestone and iron slag filters for phosphorus removal from wastewater.
- To compare filter performance under laboratory and field conditions.
Main Methods:
- Laboratory and field studies using packed columns with limestone and iron slag media.
- Investigated effects of temperature, algae presence, and hydraulic retention time (HRT).
Main Results:
- Both limestone and iron slag removed phosphorus, with performance varying by limestone type.
- Higher temperatures and algae presence improved phosphorus removal, likely due to pH elevation.
- Field results showed iron slag achieved 72% removal (12-hr HRT) versus 27% in the lab, while limestone showed 18% in the field versus 64% in the lab.
Conclusions:
- Limestone and iron slag are viable media for phosphorus removal in wastewater treatment.
- Significant discrepancies exist between laboratory and field performance, necessitating in-situ validation.
- Filter media selection and operational conditions (e.g., HRT) must be optimized based on real-world application.