Sink Blackwater System

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  • Kitchen sink water, due to its potential for high organic matter loading, is considered blackwater in design practice
  • The Seed Eco-Home uses a 2-tote Open Source Biodigester design, where the kitchen sink feeds the biodigter with active pumping via a macerator lift pump.
  • To prevent gases from escaping, use a p-trap
  • To prevent clogging of p-trap, get a p-trap with cleanout
  • Also with use of a Garbage Disposal it offers a more convienent, and sanitary alternative to a Compostable Waste Temporary Storage Bin (compost pail) type solution)
    • Ie flush down grinder, and drain to Anerobic Digester / Drying + Dry Compost System, rather than have stuff festering inside the kitchen


Sink Feed Concept



Data Collection

  • The Sink Feed Concept above with 4" down-pipe contains only about 1.3 gallons volume total (about 2 feet of length total)
  • Interesting, this low volume made it such that the 1.4 gallon volume of the water pipes going to the biodigester (about 35 feet of 1" pipe), whenever pump was shut off, would fall back down and cause backflow into the sink, fouling the air
  • It turns out that the check valve (see design above) does not work in practice with sink blackwater
  • Thus, the design was modified to enlarge the storage volume of water and add a p-trap, so when backflow occurs, there is no backflow into the sink, and there are no gases escaping from the sink

About P-Traps


P-trap and air admittance valve:

  • Check.pngStudor Redi Vent - $13 - [2]
  • Mobile home vent - $4 - [3]. Note - Amazon reviews apparently state that people who get the mobile home vents end up getting the Redi-Vent, being unhappy with the mobile home version