Horizontal vs Vertical Flow Constructed Wetland

  • BPopov
  • BPopov's Avatar
  • Ecologist involved with ecosanitation in Ukrainian Carpathians
  • Posts: 122
  • Karma: 6
  • Likes received: 39

Re: Horizontal vs Vertical Flow Constructed Wetland

Hello Detlef!
Yes, that's right -- I didn't thought about total inlet-outlet head.

I think we really have properly understand the role for plants in the CWs. Although it seems like they play not too significant role in water purification compared to microrganisms but t their evapotranspiration effects might be something valuable if we need to get rid of water. And probably HCW would be a better system for that specific effect (correct me if I am wrong) than VCW (due to longer HRT). I tried to bring up the issue of wind effect on evapotranspirtation in the CWs in the other thread forum.susana.org/forum/categories/241-co...it=12&start=24#17152
Maybe we can discuss it here?

Bogdan Popov
The Ecosolutions Forge
www.ecoforge.org
You need to login to reply
  • alexandra85
  • alexandra85's Avatar
    Topic Author
  • Posts: 32
  • Karma: 4
  • Likes received: 19

Re: Horizontal vs Vertical Flow Constructed Wetland

Dear Detlef

Thank you for your useful input. In our case, the VFCW is part of a DTF. It is the last module of the treatment chain (see description in the siphon post and the DTF layout posted in the sticky post at the beginning of the discussion thread). We will first test the efficiency of our DTF (and therefore VFCW) with the settler and ABR as pre-treatment. If our results are below expectations, we might consider an anaerobic filter prior to the VFCW. Until then, let's see. We will for sure keep you posted.

All the best

Alexandra Dubois

Technical Advisor
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
Nairobi, Kenya
You need to login to reply
  • vitek
  • vitek's Avatar
  • Constructed wetland, landscape and hydrology specialist
  • Posts: 4
  • Likes received: 1

Re: Horizontal vs Vertical Flow Constructed Wetland

Dear Alexandra and all others,

I think we are missing the main point in this discussion and it is - what are the limits for the effluent from the system? Because different wetland types are suitable for different uses.
Simply said VFCW is a aerobic - nitrifying system, so it is focused on reducing the NH4 (not the nitrogen as it was wrote before). HFCW is anoxic/anaerobic system so it's not capable of reducing NH4 but it's still good for organic compounds (BOD, COD) and solids.
So if the focus of the treatment plant is the total nitrogen you can't use any of these on its own. It should be combined or the water should be recirculated.
It can't be said that VFCW is better than HFCW if you don't know all the circumstances and demands on the treatment system.
VFCW is definetely more efficient system but more complex to design and build.
But I must said that for basic communal waste water treatment I would definetely recommend the french system as the most economical and reliable. (but without siphons - as I wrote in the other topic

vitek wrote: )

You need to login to reply
  • biotech80
  • biotech80's Avatar
  • Intl Research Coordinator for BORDA : Research at the Pollution Research Group in South Africa
  • Posts: 5
  • Likes received: 0

Re: Horizontal vs Vertical Flow Constructed Wetland

Hi Alexandra,

We have been operating a VFCW for several years now at our evaluation DEWATS plant in Durban.


The VFCW has about 100 squaremeters and is loaded with 8-12 cubicmeters/day.
We use a siphonchamber with a mechanical-float siphon that discharges about 4-5 times a day.
Issue is, due to limited headspace it is only about 50% of the design depth.

We go in with a COD of 200-320 mg/l with a noticeable colloidfraction composed of Long- and Mediumchain Fatty Acids due to excessive FOG-scum buildup at the beginning of the system.


After the VFCW we usually have a COD ranging from 80-120 mg/l and about a 50% NH4 reduction (which of course shows at NO3) and some P uptake as well.

After about 2 years of continuous operation there where issues with the wetland which resulted either in partial channeling (Root space) and fully clogged pores due to high colloid fraction.

We had the VFCW dry for 2 weeks and optimized our distribution pipes and removed/replanted the plants.
Now values are back in the <100mg/l range constantly.

So...from our point of view:
Works great, but Siphon and distributionpipes have to be done really properly.
Oxygen input is great in the VFCW....compared to HFCW
For Nitrification we use an aditional HFCW afterwards.

Cheers
Bjoern
You need to login to reply
  • ogeda
  • ogeda's Avatar
  • Posts: 4
  • Likes received: 1

Re: Horizontal vs Vertical Flow Constructed Wetland

I am really pleased with this initiative. I am from Kenya and My MSc thesis is on evaluating effectiveness of constructed wetland treatment system for polishing municipal wastewater. I designed Horizontal, vertical and hybrid subsurface flow wetland systems and compared their performances.My opinion is that Horizontal systems have clear design procedures as opposed to the vertical systems. I also realised that horizontal systems are prone to clogging if the substrate used has high silt content and higher uniformity of coefficient. Clogging in the vertical system is rear because of intermittent feeding of wastewater. Operation and maintenance of vertical system is however higher due to intermmitent feeding. On pollutant removal, both systems have high organic removals but phosphorous removal is low.
You need to login to reply
  • Rennie
  • Rennie's Avatar
  • Posts: 1
  • Likes received: 0

Re: Reply: Horizontal vs Vertical Flow Constructed Wetland

Hi

it was exciting to hear about your work on horizontal and vertical wetlands, are you now done with your MSc? I am also a MSc student working on flow characteristics and mass balances of vertical constructed wetlands , so I thought maybe we might exchange ideas.

Regards

Rennia





Rennia Mwenje
MSc in Chemical Engineering (Candidate)
Pollution Research Group
School of Engineering
University of KwaZulu-Natal
Durban, 4041
You need to login to reply
  • ogeda
  • ogeda's Avatar
  • Posts: 4
  • Likes received: 1

Re: Reply: Horizontal vs Vertical Flow Constructed Wetland

Hi

I am almost through with the process of submission of thesis. working on manuscripts for publication in journal
You need to login to reply
Share this thread:
Recently active users. Who else has been active?
Time to create page: 1.463 seconds