Biological Slow Sand Filter
Basic Design

Oil Drum Slow Sand Filter

Slow sand filter prototype
a. Goal: Remove microorganisms and pathogens from low turbidity water to make it potable
b. Benefits of the specific technology to the community
  • Low cost, low maintenance water treatment
  • Will greatly reduce the risk of water-borne illnesses
  • Will mostly likely need to be used in combination with other treatment systems
c. Local Availability: Check availability sand (grain size 0.15-0.3 mm), gravel, oil drums (height of 0.5 - 1.5 m), concrete, plastic barrels (height of 0.5-1.5m), non corrosive piping
d. Regulatory or Industry Standards for Implementation of Technology
i. International Standards: WHO drinking water standards
ii. Local code enforcement
e. Description of Product (s) or Process (es) and its Functionality (Succinct but Detailed Enough)
This slow sand filter functions because of a biological layer or "schmutzdecke" which kills microorganisms and pathogens in the water that pass through. The filtration process is slow as the effectiveness of the biological layer increases with contact time with the water. As the water passes through a filter, it encounters a diffuser plate then a layer of fine sand, coarse sand, and gravel. The water then exits through a pipe to a water basin of some sort.
f. Design parameters
i. Sizing
ii. Materials needed for Fabrication/ Construction of Technology
1. Various Options

Oil Drum
Plastic Barrel
iii.Other resources Needed for Implementation/ Use
  1. Construction Equipment
  2. Labor
  3. Technical Consultation
  4. Transportation Requirements
  5. Energy Requirements - only human labor
  6. Space
  7. Spare Parts - piping, sand refills in filter
  8. Time for Construction
iv. Technical Skills Required to Operate or Utilize
  1. Training Requirements
g. Associated Costs
i. Capital
ii. Operations & Maintenance
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