Actively aerated treatment wetland systems (engineered wetlands, EW)
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Actively aerated treatment wetland systems (engineered wetlands, EW) 03 Feb 2014 11:00 #7207

  • AquaVerde
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Dear Colleagues,

Find attached PDF of Dr. Jaime Nivala of UFZ Leipzig, Germany. She translated for SUSANA her past DWA-presentation to English language.

It is about horizontal- and vertical-CW with very small space requirements.
To my surprise with up to x1,000!!! higher degradation rate compered to "normal" CW's. This "low-tech" "intensive aerated CWs" was very new to me.

Maybe you heard already about this "low-tech" technology: "intensive aerated CW", developed by Scott Wallace, USA in 2006. Unfortunately it is patented: "Forced-bed AerationTM"...

- VAp 0,6 m2/p.e.
- HAp 0,9 m2/p.e.
- Energy demand for intensive aeration 0.16 kWh/m3 (based on a plant with 5,500 m3/d)
- CW-body is nearly full submerged (dammed), which is very different to "normal" vertical CW's
- On the bottom of "normal" designed CW they have several 16 mm PE-pipes like it is used for irrigation purpose. Instate water air is pumped in and through the coarse CW body.
- The horizontal flow version have the advantage of high E-coli removal rate.
- only 10 h/d aeration via PV (photovoltaic system) is possible/enough.

This application is in my opinion very applicable for very densely populated urban areas.
In my opinion it is not the right choice for typical rural settings.

Maybe you are not surprised if I suggest to have in front of such system an improved septic tank (Biogas-ABR), in my opinion would make this combination a DEWATS with a very small footprint (very compact DEWATS).

Furthermore you can imagine by your self through this air-pipes on the bottom of this EW you may put through other liquids and particles too treat very problematic industrial sewage, see e.g. the "Sulinger-CW's" forum.susana.org/forum/categories/36-con...iversity-bremen#7165

More details in attached PDF. Dear Moderators may you take this public presentation in to your SUSANA-online library.

Regards,
Detlef SCHWAGER

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Note from Moderator: The attached PDF can now also be found in the SuSanA library in the following entry: www.susana.org/lang-en/library?view=ccbk...p;type=2&id=1940
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Last Edit: 06 Feb 2014 13:08 by secretariat.

Re: Actively aerated treatment wetland systems (engineered wetlands, EW) 03 Feb 2014 12:49 #7224

  • JKMakowka
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Not sure if something as simple and obvious as that should be "patentable"...

I think in combination with those wind driven pond-aerators it could be a quite interesting system for some locations. With a vertically mounted wind turbine (en.wikipedia.org/wiki/Vertical_axis_wind_turbine) on top of a tall building it could even be quite interesting for urban settings.
Krischan Makowka
Technical Adviser at the Uganda Water and Sanitation NGO Network (UWASNET)
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Re: Actively aerated treatment wetland systems (engineered wetlands, EW) 05 Feb 2014 08:27 #7247

  • F H Mughal
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As it appears, the system uses fine bubble aeration. Bubble aeration increases the treatment efficiency and, has relatively higher oxygen transfer efficiency. It may reduce the power costs. As experts in water and wastewater engineering know, smaller bubbles give more bubble surface area per unit volume. Interest in bubble aeration gained momentum in early 1970s, due to the energy crisis. Some plants have both coarse and fine bubble aeration systems.

While the bubble aeration gives high oxygen transfer efficiencies, there are some disadvantages to its credit. The aeration basin must have some mechanism for easy dewatering of the contents, due to the cleaning of the pores. This is because the diffusers are subjected to biological and chemical fouling (this impairs oxygen transfer efficiency, as well), requiring frequent cleaning, at a cost, which may be significant. Based on my experience, I always find cleaning a troublesome process.

Mixing of the aeration basin contents is directly related to the oxygen transfer efficiency, and so is the airflow distribution in the basin and selection of rational airflow control diffusers.

F H Mughal
F H Mughal (Mr.)
Karachi, Pakistan
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Re: Actively aerated treatment wetland systems (engineered wetlands, EW) 07 Feb 2014 11:56 #7293

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@ JKMakowka:

Yes, the concept of providing aeration without connecting to the energy grid is a very nice idea. This could be done, as you mention, with a windmill, or with solar power. We have installed a small windmill with a diaphragm air pump at one of our research wetlands here in Germany. You can read about it in the proceedings of the WETPOL conference that was held in Nantes, France in October 2013. Please refer to the page number 186 for the full abstract.

www.emn.fr/z-ener/wetpol2013/uploads/boo...BOOK-ABSTRACTS-7.pdf
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Re: Actively aerated treatment wetland systems (engineered wetlands, EW) 07 Feb 2014 12:02 #7294

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@ F H Mughal

The aeration system in these wetlands is NOT provided by a fine bubble diffuser. The full description of our research facility can be found in the attached PDF (Nivala_2013a).

Rather, drip irrigation lines (commonly used for soil wastewater dispersal) are used to deliver air to the bottom of the wetland cell. As far as I am aware, fouling issues have not been reported in aerated wetlands treating domestic wastewater.

However, in situations where high concentrations of iron occur, the oxidation iron can create fouling / clogging issues in the air line. I have experience of this happening to a pilot-scale horizontal flow aerated wetland treating landfill leachate in Iowa (USA). Please refer to the PDF (Nivala_2007) for further detail. In such cases where oxides can form in extremely aerobic environments, extra pretreatment steps may be required in order to keep the aeration network from fouling.

Note from Moderator, the abovementioned Nivala articles can be found through the following links (Moderator: RG)
Nivala 2013: www.sciencedirect.com/science/article/pii/S0925857413000566
Nivala 2007: www.sciencedirect.com/science/article/pii/S0048969706009600
Last Edit: 14 Feb 2014 14:59 by secretariat.
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Re: Actively aerated treatment wetland systems (engineered wetlands, EW) 07 Feb 2014 12:25 #7296

  • AquaVerde
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Dear Moderator,

May you add Ms Nivala's 3 papers to SUSANA-online library too, maybe in a section "engineered wetlands, EW"?

Regards,
Detlef SCHWAGER

Note from Moderator:
Dear Detlef - Thank you for the suggestion. However, at this time the articles cannot be added to the library due to the copyright. (Moderator: RG)
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Last Edit: 14 Feb 2014 15:03 by secretariat.
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