Dear Colleagues,

Coming back to our old 2013 discussion, "how to get rid-off green-house-gases like Methane" after a simple AD-wwtp step. (AD= anaerobic digestion)

Methane (CH4) can not go in solution with Water (H2O), but after an AD it is still connected to effluent as very small bubbles which can not float up immediately. After "enough" time this very small bubbles connecting to each other and floating. "Normally" this Methane in effluent will separate to the atmosphere later within any aerobic wwtp step.

Maybe this Methane-rich effluent could still be "used" for an anaerobic DE-NITRIFICATION , as Methane could be the carbon-rich reducing agent in an anoxic or hypoxic environment. Probably a partly anaerobic horizontal CW or better an enclosed trickling "filter" as a growth substrate for anaerobic bacteria (bio-film) could be used as a de-nitrification step with the help by Methane.

Any sharing of experiences or R&D results related to "DE-NITRIFICATION with the help of Methane content in AD-effluent?" would be appreciated.

Thanks.
Best Regards,
Detlef

dear forum-moderators, maybe a new topic?
"DE-NITRIFICATION with the help of Methane content in AD-effluent?"

Ehh, "fast-shots" rarely do good for technology uptake and testing

35cm also seems rather thin, and I am not sure about the "structure" of dried peat one can buy easily. Maybe it just needs some time for a proper bio-layer to develop? This time of the year (with dropping temperatures in Germany) might however not be the best for that.

Last but not least: please don't mix up the (tested) aerobic intermittently loaded peat-filters with the (theoretical) microaerobic upflow design I proposed. The former really needs the time no waste-water is added and the water can drain so that the aerobic bacteria can do their work on the peat-matrix deposited solids.

Dear Julius,
some surprising news to me on your original idea on peat-filters:
(sorry, not really a susana-topic anymore) maybe just good for a smile...
My colleague and I agreed not to purchase peat by a middlemen peat dealer as it is much too expensive. To my surprise my college (normally a sound and down to earth guy) installed recently a 35 cm aerobic up-flow peat filter 2 x 0,7m as a layer between pebbles stones as part of his circular system (sewage --->ABR+CW+sanitation sand filter+pool --> WC&WM). Nevertheless, very enthusiastic he spend more them 100 EURO for peat, even not waiting for my promised metric filter flow calculations.
All his design been only based on my past sketchy verbal explanations by phone, as he do not understand English of your US-web link. Unfortunately the water flow through peat-filter is up to now too high. Anyway we agreed to test at in- and outlet for P and N nutrient levels, I guess only to be disappointed and finally to swear on "American filter technologies"...

the peat "saga" will be continued .
All the Best
Detlef

This is an interesting discussions. Students of water and wastewater engineering division will find this extremely helpful.

F H Mughal

Some more background literature I found:

www.wetlands.org/LinkClick.aspx?fileticket=v4vnSMS3Nvs=
(general info on Methane emissions from peat soils, detail info on root impact)

www.gret-perg.ulaval.ca/uploads/tx_centr...drolProc_2009_03.pdf
(details on how one could vent methane from the bottom peat area and other related info)

www.env.uwaterloo.ca/u/jsprice/index.htm.../kellner_etal_05.pdf
(dynamics of gas bubbles in peat)

www.laurentbazinet.fsaa.ulaval.ca/upload..._Waddington_2006.pdf
(how the gas bubble can make peat float etc.)

www.benthamscience.com/open/togeogj/arti...OGEOGJ/67TOGEOGJ.pdf
(how floating peat forms naturally, e.g. this is basically what one would want to emulate)

Sure, some substitute would be great, but as all the papers describe difficulties growing the special microbial community (it's probably more than just that special one) outside of its natural habitat, it might not be that easily done.

What I could imagine to work is to first fill the pond with cut reed or papyrus (with green leaf material to have a better NPK-carbon ratio) and run it for a year or two in intermittent aerobic mode, so that the fibrous plant material has some time to start decomposing. Then you would add relatively nutrient rich and decomposed organic material (mixture from humus and manure?) to the bottom and let it sit for a while for the anaerobic bacterial community to start (during that time one could just run it as a open septic tank already, to avoid downtime of the system?).
But who knows, what will work best. When using peat directly chances are for sure higher to get something working to test the general concept in praxis.

Edit: basically one has to think about how peat is created naturally, and that is by decomposing fibrous plant material in an water-logged area, so that anaerobic (and acidic) conditions are created. The problem likely is that it is a rather slow process.

But maybe another "cover" material that lets water seep through, but inhibits the oxygen-diffusion downwards somewhat can be found?

Edit2: Maybe first heat-composting the plant-material for some time, can yield a fibrous humus like substance that can be turned into artificial peat more quickly?

Yes, some peat have to be used for inoculating Coconut fiber. The papers say, the bio-experts found this special bacterium in peat.
IFs are the starting point for our thinking exercises

AquaVerde wrote: Maybe to get the important denitrifying methanotrophic bacteria, ‘Candidatus Methylomirabilis oxyfera’ just to start the process by putting a layer of peat ("soil" from the DIY-store with 95% peat) on top of Coconut fiber "filter".

Yes, I was thinking about something like this when saying "substituting" above.

If I've I got it right, it's the specific tpye of bacteria you want to have (that grow naturally on peat) but it's not the peat itself you need. So if you maintain the conditions the bacteria need to thrive, they would grow on other support material as well. If you don't manage to maintain these conditions, they would also die off on peat... Lots of "ifs" here, I know

Dear Julius & Florian and Others,

On the use of peat for small scale I would not have a problem, on large scale I am hesitating like Florian too.

Therefor, how about using mainly Coconut fiber residues instead of peat? Maybe to get the important denitrifying methanotrophic bacteria, ‘Candidatus Methylomirabilis oxyfera’ just to start the process by putting a layer of peat ("soil" from the DIY-store with 95% peat) on top of Coconut fiber "filter".

Any thoughts on substituting peat are welcome!

All the Best
Detlef

Ok, but that will be an aerobic peat-filter, right? How does that pool get so contaminated with N & P in the first place?

Otherwise, sorry no, I just stumbled on these yesterday (+ the other link above: www.envirolink.govt.nz/PageFiles/173/121...eatment-Gisborne.pdf which mentions some other interesting papers in their references).
Before I was mainly looking into anaerobic, stratified organic mud-layers for pond lining (so called "gleying") and other similar things, but ultimately some of the details from that might somehow be applicable to the idea proposed above too.

The aerobic version of a peat-filter I can't say too much about, but it seems to me that since they are using dried (and thus dead) peat, it is probably not too much different from any other organic matrix filter, like for example the coconut husk filter presented not too long ago on this forum.

Dear Julius,

I just discussed the possible nutrition reduction option of a swimming pool via CP with my college.

Existing is a wwtp (ABR, CW + CW for hygienisation) to feed a swimming pool. Sound maybe crazy to you, but it is functioning well. Still P & N is too high as you can see on the picture: http://www.aqua-verde.de/page4.php?view=preview&category=9&image=71
We will start it very soon, using 3 old PE-tanks 2 x 0,7 x 1,4. We will start with one module and will test P & N before and after. If successful 3 modules will be used in total. We will let you know the practical P & N outcomes.

Do you have access to more detailed background information on peat filter additional to the 2002 www.extension.umn.edu/distribution/naturalresources/dd7669.html ?

All the Best
Detlef

No, skeptical comments are very much what is needed right now

Regarding the peat mining, I can understand your concern, but as far as I can tell most peatlands actually have the problem that they are of no value unless drained. Thus introducing a way those can be used without large-scale draining might be beneficial overall. But yeah, that's probably too much positive thinking...

About the proposed technology... I guess it is rather a way to simplify the construction of a waste-water biodigestor (as it needs no gas dome at all) with the added benefit that very little methane should be leaking into the athmosphere and the reduction of nitrates in the effluent.

My greatest concern is actually that the overall load capability and specific permeability of the upflow peat-filter might be very low, thus requiring a large surface area. That in turn would drive up costs and also make capturing the excess bio-gas probably not possible/very difficult.