What Material for Non-Corrosive Pipes in Compost?

Click For Summary

Discussion Overview

The discussion revolves around selecting a suitable material for non-corrosive pipes to be used in an anaerobic digester system that utilizes heat from compost bins. Participants explore various materials and their properties in relation to thermal conductivity and corrosion resistance, considering practical applications and environmental conditions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests using plastic pipes due to their low cost and long lifespan, despite their low thermal conductivity.
  • Another participant proposes copper for its high thermal conductivity but raises concerns about its compatibility with compost and cost.
  • A suggestion is made to consider stainless steel piping, although it is noted that it may be expensive.
  • Concerns are raised about the presence of oxygen where the pipes would run, indicating that stainless steel might not be suitable in anaerobic conditions.
  • A later reply questions the reasoning behind avoiding stainless steel in anaerobic environments.
  • One participant recommends using plastic piping designed for under-floor heating, highlighting existing knowledge and resources available for such applications.

Areas of Agreement / Disagreement

Participants express differing opinions on the suitability of materials like plastic, copper, and stainless steel, indicating that multiple competing views remain regarding the best choice for the pipes.

Contextual Notes

Participants do not reach a consensus on the ideal material, and there are unresolved questions regarding the environmental conditions (e.g., oxygen presence) that may affect material performance.

Who May Find This Useful

Individuals interested in anaerobic digestion systems, composting technology, and materials science may find this discussion relevant.

bioenergyproject
Messages
1
Reaction score
0
TL;DR
I am trying to transfer heat from compost into anaerobic digestion tanks for maximum productivity from the methanogenic bacteria. The digestion tanks are to produce biogas.
So with our initial prototype for our anaerobic digester, we weren't able to sustain the right temperature inside the tanks. One idea we came up with is to use the heat from the compost bins that is only within 10-20 feet from our tanks. We plan to circulate the fluid inside the digestion tanks underneath the compost using a pump. So my question is, what is a material that has high thermal conductivity and would not rust or corrode underneath compost?

We put fruit peels, coffee grounds, paper dishes and bowls, vegetables, peoples leftover meals, and some other stuff i can't remember off the top of my head into the compost.
 
Engineering news on Phys.org
:welcome:

In case of limited thermal transport the usual answer is the most common plastic pipe. The thermal conductivity is low, but it is cheap to extend the surface and (in normal circumstances) it has long lifetime. It is also easy to use.
Copper would also do (high thermal conductivity) but I don't know how it would fit with the compost. Copper is often considered to have some antibiotic properties. It is also not cheap and more vulnerable to movements (compost is expected to shrink and move).

Are you sure the compost heap can/will produce enough heat?
 
  • Like
Likes   Reactions: jrmichler
Maybe use stainless steel piping? It is probably not cheap, though...

1565273739790.png
 
Is there oxygen where those pipes run? Stainless steel should be avoided in places where it is not exposed to oxygen.
 
  • Informative
Likes   Reactions: berkeman
anorlunda said:
Stainless steel should be avoided in places where it is not exposed to oxygen.
Interesting. Why's that?
 
See the below for a quick answer:
https://www.imetllc.com/training-article/stainless-steel-corrosion-resistant/
 
  • Informative
Likes   Reactions: berkeman and BillTre
Don't re-invent wheel this time around, look at the plastic piping used for under-floor heating. Lots of know-how on usage, inexpensive accessories & connectors.
;-)
 
  • Like
Likes   Reactions: chemisttree