WWT/Process Areas/TBT-WWT-030
Trickling Filter and Humus Tank Safety
Water & Wastewater Treatment › Process Areas › Trickling Filter and Humus Tank Safety
Toolbox Talk
Trickling Filter and Humus Tank Safety
Trickling filters and humus tanks are biological treatment stages at wastewater works. Filters contain stone or plastic media that support biological growth, while humus tanks settle the resulting solids. Workers face drowning, biological hazards, gas exposure, and the risk of falls on wet and uneven filter surfaces. This talk covers the specific safety requirements for working on these process areas.
Key Hazards
Drowning from falling into deep humus tanks containing wastewater
Slips on wet and biologically coated trickling filter media surfaces
Hydrogen sulphide exposure from decomposing biological growth on media
Biological infection from contact with wastewater and sludge deposits
Control Measures
- Wear a personal flotation device when working above or adjacent to filled humus tanks.
- Install edge protection around all open tank edges and filter access walkways.
- Wear non-slip footwear with good ankle support when walking on trickling filter surfaces.
- Monitor the atmosphere for H2S near enclosed filter areas and humus tank manholes.
- Wear biological hazard PPE including waterproof gloves and face protection near wastewater.
- Ensure up-to-date hepatitis A and tetanus vaccinations for all workers on the treatment works.
- Use walkways and designated access routes across filter beds, never walk on the media surface.
- Isolate and lock out rotating distributor arms before anyone works on the filter surface.
- Brief all operatives on the water rescue plan and the location of rescue equipment.
Remember
- Wear a personal flotation device at all times when working above filled humus tanks
- Use designated walkways across filter beds and never walk directly on the media surface
- Isolate and lock out rotating distributor arms before working on the filter surface
- Monitor the atmosphere for H2S near enclosed filter areas and tank access manholes
- Wash hands thoroughly before eating or drinking to prevent biological infection
Applicable Legislation: CDM 2015 · Confined Spaces Regulations 1997 · COSHH 2002 · Work at Height Regulations 2005
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