Schmutzdecke slow sand filter using biogas effluent

We had built a simple schmutzdecke slow sand filter from a plastic rain water barrel filled with stones, gravel and 75 cm of sand (see http://solarcities.blogspot.com/2009/09/shmutzdecke.html for details) to try and purify our graywater. While the water came out clean in appearance it still had that "spoiled soap" smell. Today we tried putting the graywater in our biogas digester and using the effluent (liquid fertilizer) from that in the schmutzdecke filter. Surprisingly even though the effluent from the biogas system is brown and smells strongly of horse manure, what comes out of the slow sand filter is a clear non-smelling water. This needs further study, but perhaps the trick with graywater is to feed it to the digester and let the anaerobes work on it first, hypothetically breaking down whatever compounds make greywater have that objectional odor that the slow sand filter can't get out. Then, even though what comes out of the biogas system is really bacteria laden and smelly, paradoxically the microorganisms in the slow sand filter schmutzdecke ("dirty layer" in German) seem to be able to eat them, making the water clean. We will see once we can do a bacterial analysis.

Category:

Nonprofits & Activism

Tags:

• Schmutzdecke
• slow sand filter
• biogas
• anaerobic bacteria
• water purification
• greywater
• graywater

[4micaman]

"We're not professionals and please do try this at home!" haha - that was great! Nice reference to "The Road to Serfdom" too!

Thanks for sharing your experiments.

[3DCGdesign]

Tim - Please check out this great bio filter by biorealis "biofilter/drumbiofilter" it only uses a very low energy aquarium circulation pump and a tiny ozonator - see it in Alaska Bioshelter video on youtube

[chaga74]

Great experimentation!

It's a shame to throw away the fertility in that stinky biogas effluent, though. Living soil would also be a great filter, through which the fertility could be harnessed for food production.

Alternately, you could use the effluent to compost carbon-rich substrates, like straight-up sawdust/woodchips. Either a heap, or a sawdust/woodchip "filter" would take the stink out AND recapture the fertility.

[MrMENRIQUE2]

great work, how often do you change the sand?

[kmdental36]

Good job. The free world will prevail. This is the cause to fight! The world needs more people like you. Keep up the good work!

[gfeuchte]

you guys want to clear the smell plug an ozone generator to aerate the gray water tank and that kills the smell.

[tulius01]

Great and very informative video! Thanks, I really did appreciate it.

Aquarium owners do use porous clay rings (Raschig rings) to help the beneficial bacteria to build colonies and stabilize in their aquarium filters. An expedient method could be the use of clay flower pot fragment. Just a thought.

[c0ldelement]

better reverse osmosis systems that are more effective for filtering that water.. but excellent that you used bacteria to break down some of the compounds remaining in the water...very cool!

[Q300SBJ]

G'day Mate, impressive. I'm hoping to set up a slow sand filter to filter my gray water to a standard clean enough to run through an electric pump with pressure sensor, the type that would be damaged by straight gray water. Couple of Qs

1 Did you use a layer of charcol in your filter?

2 Do you think the filtered gray water would be clean enough to run through the pump I described above, I'm not bothered by the smell it will be used just to hose the lawn?

Hope to hear from you. Cran Australia

[d3adp001]

your certainly commited.