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Published on: March 24, 2023
Dissolved oxygen, COD, nitrogen and phosphorus profiles in a continuous sand filter used for WWTP effluent
Hongbin Xu1, Sigrid M Scherrenberg, Jules B van Lier
1Department of Environmental and Municipal Engineering, Zhengzhou University, 100 Science Road, 450001 Zhengzhou, China.
Summary
Continuous sand filtration effectively treats wastewater, with most biological activity and nutrient removal concentrated in the lower filter bed. Optimizing conditions can meet strict European water quality standards for nitrogen and phosphorus.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Wastewater Management
Background:
- Continuous sand filtration (CSF) is a potential method for extensive wastewater treatment plant (WWTP) effluent management.
- Applications include water reclamation and meeting restrictive discharge regulations.
Purpose of the Study:
- To investigate concentration profiles within CSF beds.
- To determine the impact of operational conditions on bacteriological conversions and nutrient removal.
Main Methods:
- Analysis of dissolved oxygen (DO) and chemical oxygen demand (COD) profiles along the filter height.
- Monitoring of nitrogen (NOx-N, N-total) and phosphorus (P) removal efficiencies.
- Evaluation under varying hydraulic and sand velocities, independent of methanol dosage.
Main Results:
- Bacteriological conversions and most nutrient removal occur within the lower 0.4-0.9 meters of the CSF bed.
- Dissolved oxygen rapidly depleted below 1 mg/L within the first 0.4 meters.
- Observed DO decrease correlated with COD reduction.
- Nitrogen removal was confined to the initial 0.9 meters of the filter.
Conclusions:
- Optimizing CSF operational conditions is crucial for effective wastewater treatment.
- Achieving stringent European Water Framework Directive effluent standards for nitrogen (2.2 mg/L) and phosphorus (0.15 mg/L) is feasible with CSF.
- CSF demonstrates significant potential for advanced WWTP effluent polishing.
