CW in arid zones

Lotan, located in Israel’s Southern Arava Desert, is an ecology conscious community with a focus on sustainable development. It is also home to a large and significant bird reserve. With an awareness of Lotan’s governing ethos, Ofra Aqua Plants designed a self-sustaining system that can also provide environmentally friendly water for bird ponds and irrigation.

 

The choice of Constructed Wetlands for such an arid zone is not self-evident. Traditional CW using Phragmites australis do not have a good reputation for their use in water conservation and desalination.  Constructing a CW system in the desert requires special characteristics.  Ofra Aqua Plants has led vast experimental efforts to identify plants, substrates and flow systems that will result in actual reduction of Chlorides and Boron levels in these harsh conditions. At the experimental site, a source of saline water was used (1,200 and 3,000 mg/l of Chlorides), and within 2 years the beds had achieved a significant reduction in salinity levels. (Graph attached.) As expected, high salinity was measured in the control ponds.

 

 

The knowledge gained from our research was put to the test when our company designed the Neot Smadar water reservoir, situated in the Arava Desert. Special wetland beds were constructed to surround the shores of this 27,000sq.m pond.  The water is pumped and distributed through these beds.

The reservoir is used for irrigation, and as a fish farm.  Although the water source is slightly saline, even when combined with the addition organic load from the fish, the water at the outlet is better than in the inlet and fit to be used for irrigation. The Neot Smadar pond now attracts many bird species not seen in the region for many years, and as a result has established itself as an important bird watching site.

 

The Lotan system was designed using the following guidelines:

1.     The system is designed for minimum water loss by evapotranspiration, choosing suitable plants, substrates and flow systems.

2.     A poly-culture system is used to enhance stability and effectiveness of the system.

3.     Both human and animal needs are taken into account. The system provides shelter, water and food for wild animals (especially birds) and a green tranquil place for human recreation. Esthetic considerations are a part of the design concept.  The wastewater system is incorporated into the bird watching park and its bird pond. Trails, watchtowers, and sheds are incorporated in the design. 

4.     The design ensures no odors, mosquitoes or any other nuisance in the system. Heavy organic load from the dairy farm is pre-treated on the farm premises to avoid odors at the main system.

 

 

The Constructed Wetlands system is self-sustaining and requires no maintenance.  While it does require observation and monitoring as well as some gardening for esthetic and tourism purposes, gardening is not required for the system to function.  Its effectiveness and efficiency when coping with a diverse range of pollutants, together with its seamless integration into the environment, make Constructed Wetlands the solution for our times. The Ofra Aqua Plants system has proved its effectiveness in arid Zones with their special requirements. 

salionity and conductivity reductioin graph

salionity and conductivity reductioin graph