Purification

AquaFlora Floating Wetlands have been designed to provide a green solution to improve the water quality through biological processes within their root systems. These processes are supported by the Xylit fiber which makes these floating wetlands unique.

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Vast root systems promote biological processes which naturally support purification

With the highest density root system, AquaFlora Floating Wetlands provide a large surface area for the biological processes of microorganisms.

These processes can be described theoretically. In practice, they are always dynamic processes with diverse interactions that defy a simple description.

Bacteria:

Bacteria break down and mineralize organic substances that dissolve in water. Thanks to the floating islands, the mineralized organic substances, mainly nitrogen and phosphorus, are absorbed by the plants, achieving an improvement in water quality.

Of the various biological processes, denitrification and phosphorus removal are the most important for water purification.

Denitrification and Nitrification

Denitrification is a process with aerobic and anaerobic phases that takes place under floating islands. This depends on the structure and shape of the floating island and the movement of the water. In a test in Montpellier, France, the following results were achieved in a pond:

Phosphorous removal

A key process to reducing phosphorus (in addition to its absorption thanks to the Xylit fibers) is physical deposition. The phosphorus sticks to the roots and sinks to the bottom. This process is supported by the reduction of water movement through the root system.

Biological process	% reduction
Nitrification (removal of BOD)	73-92 %
Denitrification (removal on N)	69-99 %
Phosphorous removal	38-69 %

Table with the % reduction of the main biological processes in AquaFlora Floating wetlands

Microorganisms:

Bacteria are not only responsible of the biological processes in the wetland but also the food base of thousands of microorganisms like protozoa, calanoida, water fleas, ostracods … Microorganisms feed also on algae and represent the second level of a diverse and dense food chain thanks to the introduction of our floating wetlands.

Example of a water flea (Cladocera sp.) found in AquaFlora Floating Wetlands

Macroinvertebrates:

The algae and microorganisms that are found in our systems become food for snails, molluscs, small crabs, dragon flies and that is the reason why we find a high density and diversity of macroinvertebrates in AquaFlora Floating Wetlands.

Macroinvertebrates are significant within the food chain as larger animals such as fish and birds rely on them as a food source. They are particularly important as an effective algae filter causing a reduction in the algae biomass and improving the visibility in water.

Macroinvertebrates communities found in AquaFlora Floating Wetlands after 10 years of their installation.

(1: Gammarus pulex, 2: Lymnaea cf. Oblonga, 3: Libellula quadrimaculata, 4: Planorbida sp., 5: Bithyniidae sp.)

ESWEG group has participated in different projects in Europe, mainly Germany, France United Kingdom and Spain to demonstrate the water purification capacity of AquaFlora Floating Wetlands.

Added value with Xylit fiber

Installation of Xylit for a water purification experiment

Xylit fibers are fibers that are produced in large quantities as a by-product of lignite production.

The surface of the Xylit fibers offers, on the one hand, a high rate of phosphate and nitrate adsorption, a stabilization of the chemical and physical properties of water and a faster colonization of microorganisms (high biological activity).

As we now know from many studies, Xylit fiber has a large surface area (in the case of organic substances) and a high adsorption rate of phosphate and nitrates. The adsorption rate per kg of Xylit was 12.9mg for phosphate and 22.4mg for nitrate.

Day	Phosphate (mg/L)	Nitrate (mg/L)	Microorganisms population
1	399	850	1,2 x10⁶
5	26,6	349	2,4 x10⁶
14	17,7	420	3,5 x10⁶
29	7,9	364	2,0 x10⁶
39	8,1	411	8,2 x10⁶

Table "Nutrient Degradation and Development of Microorganisms"

Phosphate absorption in water with Xylit

Three days after filling with PO4-P with 2,0 mg/l the concentration in the water was reduced by approx. 85 %.