Both graywater and nutrient rich liquids or stabilized solids from primary treatment processes can be used as feedstock in fish and/or water plant farming.
Treatment Level: Secondary
Relative Cost: medium – high
Amount of Maintenance Interaction: medium – high
Beneficial Byproduct: lots (fish and/or plants)
Advantages
- Low energy waste treatment that aides in fish production.
- Food security and nutrition.
Disadvantages
- Large space needed for fishponds.
- Extreme care must be taken to avoid potential bacteria in pond water, on plants and on the fish.
- Need access to experts to develop a hazard and risk management plan.
Operation & Maintenance
- After waste/graywater has been treated and/or stored for 4-10 weeks, add it to the aquaculture pond.
- Visually inspect for undesirable vegetation, insect larvae growth, and snails.
- Pond water quality is essential to avoid contamination and pathogen transmission. It should be monitored to set waste application and timing.
Additional Notes:
- Aquaculture fish and plants should not be eaten raw.
- Kitchen processes must be adjusted, such as using separate gutting and cutting knives, to avoid cross-contamination of fish flesh.
- Good practice is to keep fish in clean water ponds (or eliminate waste feed to ponds) for several weeks at the end of their growing cycle.
Salmon Aquaculture Project (www.canadaandtheworld.com)