On this page you will find answers to frequently asked questions related to sustainable water purification . If your question is not listed? Let us know.

FAQ uk

The constructed wetland filter is a powerful solution for the future, an environmental friendly, sustainable and multi-applicable way to purify all kinds of waste water in a natural way.

The waste water is pumped into the top of the sand filter, from where it percolates through the root zone of the reeds, where it gets oxydized and the nutrients broken down into smaller mostly harmless molecules. At the bottom of the filter, the water enters the drain pipes and is being conveyed into an infiltration bed.  Although the reeds are mown in late fall, the root zone remains active in winter, so the system remains active under cold circumstances.

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An IPU is a very compact waste water purification unit, that can be installed under ground, with a capacity between 4 and 500 people.

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The purification process of an IPU, is based on a combination of aerobic and anaerobic processes, that occur at the same time. The major difference with CWF’s are that an IPU is a very compact structure, composed of polypropylene tanks, linked together, in which the waste water is being pumped from one tank to the other and being aerated mechanically. By doing so, the waste water is being treated efficiently.

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This depends completely on the circumstances, like amounts of black and grey waste water, temperature, reedplants etc. But as a rule of thumb: a domestic CWF, for a four person household, should be around 16-20 m2. For a campground with 50 guests per day it should be around 170 m2, with a buffer tank probably 140m2.

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The pumping shaft should be big enough to enable the pump to move the daily amount of waste water coming in, to the filterbed in approximately 4 to 5 times, this is important with regard to the danger of clogging the infiltration piping.

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A pre-treatment facility is a storage tank that offers the suspended solids in the waste water the time to settle on the bottom of the tank. The facility is biologicaly active, meaning that bacteria are present and processing polluting components into less harmful nutrients.

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A septic tank is a larger pre-treatment facility, is has to comply with governmental regulations regarding size and volume, and is in most occasions divided into two or three chambers that are interconnected and in which the waste water can settle and start the digesting process.

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Strictly spoken it is the same as a pre-treatment facility, with as only difference that a sedimentation tank does not have to be biological active and is not prescribed to have a certain size.

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There is a choice between concrete and man made materials like polypropylene or PVC. (the plastics). The concrete is usually a little cheaper, but takes more effort to put in place due to its weight, the plastics are cheaper, and are easier to place, but are more vulnerable, specially PVC gets brittle after twenty years underground.

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No, the constructed wetland filters produce no odours, if well designed and correctly built and maintained.

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No, there is nothing to eat for them, its an all natural environment, so the CWF does not attract animals or insects.

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No, when small amounts of green are eaten it would not make a difference, but in general it is recommended that you keep animals out of the CWF, with some kind of fencing, specially when the reed plants are still small.

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A CWF serving the waste water of up to four people, would cost approximately between $ 9,000 -$ 12,000 (including infiltration bed), yearly maintenance will total approx. $ 250  depending on location and size. Larger systems have different prices, please contact us for a quote.

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A small IPU (up to five people daily load) will cost approx. Between $ 8,000 and 11,000 (including infiltration bed), yearly maintenance will total approx. $ 350  depending on location and size. Larger systems have different prices, please contact us for a quote.

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The price of a septic tank ( 4000 or 5000 litres) varies between $ 3,500 and $ 4,500, depending on soil conditions and location.

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A CWF requires some maintenance to guarantee correct functioning and operation. There is always the choice to do it yourself or leave it to a certified maintenance company (which we recommend).

Main issues that have to be dealt with (once a year) are:

  • Pumpshaft inspection: check cleanliness, remove dirt and floating substances, clean the pump(s), check for corrosion and damages, check electronics and power supply.
  • Check septic tank: measure and sample sedimentation on the bottom of the tank, check for cleanliness and damages.
  • Filter inspection: Check for cleanliness of the filtersand, gravel and drains; visual inspection of the reedplants, if necessary sample the filter material. Mow the reed in fall and cover the filter for the winter period.
  • Effluent shaft: Check for cleanliness, remove sediments, sample effluent and check for smell, and clarity.
  • Final inspection of the whole system: check for damages, leaks, smell and fencing.

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An IPU requires some maintenance to guarantee correct functioning and operation. There is always the choice to do it yourself or leave it to a certified maintenance company (which we recommend).

Main issues that have to be dealt with (once a year) are:

  • Inspection of all pumps: check cleanliness, remove dirt and floating substances, clean the pumps, check for corrosion and damages, check electronics and power supply.
  • Check septic tank: measure and sample sedimentation on the bottom of the tank, check for cleanliness and damages.
  • Digestion tanks: check for floating dirt and remove it, inspect for damages and fluid levels.
  • Effluent shaft: Check for cleanliness, remove sediments, sample effluent and check for smell, and clarity.
  • Final inspection of the whole system: check for damages, leaks and smell.

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For a simple septic tank, it would cost approx. $ 125 (Excluding pumping) for an ICU it might total $ 350 and for a CWF you are looking at approx. $ 250, but these numbers can vary due to location and accessibility issues.

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No, there is no open water on top of the filter, so the mosquitoes cannot put their eggs there. Some reed plants ,may attract insects due to their smell, but the effect will be minimal.

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Effluent is the treated water that comes out of a purification unit. Normally it is fairly clean and clear, like groundwater.

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Influent is the substance that flows into the purifier, normally domestic waste water, smelly and grey.

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The smallest unit uses approx. 450 kWh/year roughly between $ 60 and $ 75  per year. Larger units use slightly more.

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A small CWF uses approx. 5 kWh/year, roughly $ 1 per year. Larger systems use slightly more energy.

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Yes, the root zone of the reeds will remain active during the winter period, but the filter needs to be protects from snow and frost.

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A general name for a water treatment system using reed plants. A CWF is just one example.

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It is the process of water slowly moving down through the filter materials.

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