Alternative to gravel stones for filter media of Constructed Wetland

  • canaday
  • canaday's Avatar
  • A biologist working toward sustainability
  • Posts: 360
  • Karma: 18
  • Likes received: 139

Re: Alternative to gravel stones for filter media of Constructed Wetland

Dear Alexandra,

How is your project going?

In the interest of brainstorming, here are some ideas of materials that could replace the gravel in your wetlands:
-- the thick shells from African Oil Palm (Elaeis guineensis),
-- intact, crushed or chopped PET plastic bottles (with their caps removed), since this plastic is heavier than water (Here they do not accept certain colors in normal recycling),
-- the caps from the PET bottles (I guess these might be polypropylene.)
-- other plastic bottles that do not float,
-- unbroken disposable glass beer bottles (Do these get recycled there? Do they even exist? How much are they worth on the market?),
-- building rubble that has been screened to classify the size,
-- broken ceramic tiles from the factory,
-- charcoal or biochar, screened and graded (maybe Sanivation's fecal charcoal briquets that are made in Kenya).

The main reason for using this gravel is to keep sand from filling and plugging the pipes. I have an idea of how to greatly contribute to this protection with the PET plastic of 3-liter bottles. I worked it out for a project out in the jungle, where there is no gravel, but we still have not done the project, for lack of funding. I can explain, if this sounds interesting.

Best wishes,
Chris Canaday

Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
You need to login to reply
  • alexandra85
  • alexandra85's Avatar
    Topic Author
  • Posts: 35
  • Karma: 4
  • Likes received: 21

Re: Alternative to gravel stones for filter media of Constructed Wetland

Dear Chris

Thank you for your answer. The project is going on well, we are still at the construction phase,trying to finalise the decentralised treatment plants as best as possible. For the filter material in the wetland we have opted for crushed stones (ballast) but only for the locations where round gravel (from rivers) are not available. It would be very interesting to study and compare the efficiency of the different alternative materials you are suggesting. I would be interested to hear about your idea of protecting the drainage pipe with PET plastic. Are you speaking about the plastic pellet or the actual bottle?

Alexandra Dubois

Technical Advisor
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
Nairobi, Kenya
You need to login to reply
  • alexandra85
  • alexandra85's Avatar
    Topic Author
  • Posts: 35
  • Karma: 4
  • Likes received: 21

Re: Alternative to gravel stones for filter media of Constructed Wetland

Dear Juan

Thank you for the reference. I managed to find the related description in English and it was quite helpful.

Greetings from Nairobi

Alexandra Dubois

Technical Advisor
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
Nairobi, Kenya
You need to login to reply
  • canaday
  • canaday's Avatar
  • A biologist working toward sustainability
  • Posts: 360
  • Karma: 18
  • Likes received: 139

Re: Alternative to gravel stones for filter media of Constructed Wetland

Dear Alexandra,

My idea is to use the cylindrical part of the 3-liter PET bottles, which are roughly the same diameter as 11-cm PVC pipe. They also get slit up one side, such that they COULD open up flat. A hole gets melted with a hot nail in each corner. A 1-cm-diameter rope gets tied spirally around the perforated drain pipe. The PET gets stitched with string around the pipe and rope, such that the gap runs along the bottom. The crushed tops and bottoms of the bottles are placed under this gap, on the bottom of the excavation.

With this, sand and silt cannot filter, with water flow and gravity, into the pipe. They would have to be carried up 5 cm vertically, but not directly, due to the rope, the tops and the bottoms.

This is a bit labor-intensive, but doable, and the worst thing would be to build the wetland and have it plug. Recylers would be glad to provide the bottles at some low cost, and it would not matter if they had previously been crushed.

Good luck with your project. Let us know how things go.

Best wishes,
Chris Canaday

Conservation Biologist and EcoSan Promoter
Omaere Ethnobotanical Park
Puyo, Pastaza, Ecuador, South America
inodoroseco.blogspot.com
The following user(s) like this post: Carol McCreary
You need to login to reply
Share this thread:
Recently active users. Who else has been active?
Time to create page: 0.875 seconds