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Impact of surface maintenance on BioSand filter performance and flow
Sarah Singer1, Brain Skinner1, Raymond E Cantwell2
1WEDC, School of Civil and Building Engineering, Loughborough University, The John Pickford Building, Loughborough, UK
Journal of Water and Health
|April 1, 2017
Summary
BioSand filter (BSF) maintenance impacts performance. While immediate post-maintenance water (0-2 L) shows minimal impact, later water (15 L+) has reduced pathogen removal and longer recovery times, especially with sand removal.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Microbiology
Background:
- The BioSand filter (BSF) is a widely used household water treatment system.
- BSFs require periodic maintenance to remove accumulated sediments and maintain optimal performance.
- Understanding the impact of different maintenance techniques on BSF efficacy is crucial for ensuring safe drinking water.
Purpose of the Study:
- To evaluate the effects of three common BioSand filter maintenance methods on filter performance and flow rate.
- To compare the recovery time and thermotolerant coliform removal efficiency after surface agitation, stirring, and sand removal maintenance.
Main Methods:
- Four concrete BioSand filters were subjected to three maintenance methods: surface agitation (SA), stirring method (SM), and sand removal (SR).
- Effluent water was collected and analyzed for thermotolerant coliform removal rates at two stages: 0-2 L and 15 L+ post-maintenance.
- Flow rate recovery was also measured for each maintenance method.
Main Results:
- Thermotolerant coliform removal rates significantly decreased in the 15 L+ effluent after all maintenance types (0.32-0.91 log reduction).
- No significant decrease in coliform removal was observed in the initial 0-2 L effluent, regardless of maintenance method.
- Recovery periods varied, with sand removal showing the longest recovery (12.75 days) for the 15 L+ effluent, while SA and SM had shorter recoveries (3.9 and 3.0 days, respectively).
- Flow rate recovery was highest for sand removal (138%) compared to surface agitation (76%) and stirring method (82%).
Conclusions:
- Maintenance is essential for BioSand filters but can temporarily impair pathogen removal, particularly for later effluent volumes.
- The choice of maintenance method influences the duration of performance recovery and flow rate restoration.
- Sand removal, while effective for flow rate recovery, leads to the most significant and prolonged reduction in pathogen removal efficiency.