Wednesday, January 07, 2009 10:14 AM
Purified sewage from Kfar Saba and Hod HaSharon is about to undergo a transformation. The renovated regional sewage purification plant will purify the water to the level suitable for agricultural use, after which it will be pumped into the Yarkon River.
Thus, the purified water will actually decrease the level of pollution in the river, whilst providing the water for the foundations of a natural park to be built in south Hod HaSharon near the Yarkon Junction.
The purification facilities renovation should be completed this February. The water will then undergo three purification stages: removal of nitrogen and oxygen, filtering through sand and sterilization through a UV system. The Yarkon River Authority will install a pipeline to bring sewage water to the river that is sufficiently purified to meet Inbar Committee codes. The water will then undergo additional purification by means of the wetlands technique – a technique that purifies water using water vegetation. The project is being carried out with cooperation between the Yarkon River Authority, the Hod HaSharon Municipality, the Ministry for Protection of the Environment and KKL-JNF who mobilized contributions from the Australian Jewish Community for the project that will cost NIS 25 million and is due to be completed by the end of 2009.
The rehabilitation method based upon vegetation, found international popularity during the past decades and differs slightly in its application from one place to another. In Europe the accepted method is to move water through an underground system in which no water is exposed to air at all. In the United States the method involves exposed water – a method that is less efficient per land unit, but simpler and less expensive because there are no hydraulic considerations. This method involves large covered expanses that purify wastewater from large cities in Florida, California, and Arizona. The method is based upon the ability of water plants that grow in saturated areas to transfer oxygen into their root system and to exude other materials which, together, create an optimal ecosystem for micro-organisms capable of decomposing and consuming various pollutants.
Unlike Arizona, Israel does not have broad expanses of land where natural purification can take place in large shallow pools. “Because of our small areas we accelerate the process,” explained Dror Ben-Yoav, infrastructure advisor for the Hod HaSharon Municipality. “Air pipes will be laid at the bottom of the pools that will push air in the direction of the plant roots. The pool will then be flooded with water that has penetrated downward between the roots of the plants and will come into contact with the air bubbles. An aerobic and anaerobic system will be created by artificially inducing oxygen. This will allow the biological activity of eliminating the remnants of nitrogen in the water after it undergoes the third treatment in the purification facility.” All the plants that will be used in the green area of the Yarkon appear on a list published by the Parks & Gardens Authority and all are native to the Yarkon River area.
After purification the water will be pumped from the wetland in Hod HaSharon through the Hadar River that flows through the city and from there to the Yarkon River. “The wetland will bring pure water to the Yarkon that is as clear as drinking water and will operate in much the same way as the kidneys filter blood in the human body,” explained Ben Yoav. A dam with a pumping station has also been constructed on the Kaneh River north of the purification facility in Kfar Saba and Hod HaSharon. From there water will be pumped to the facility and prevent purified sewage water from reaching the Yarkon River through the Kaneh River. “We are actually closing the ecological circle that became the potential pollutant of the Yarkon,” explained Ben Yoav.
The project will benefit not only the Yarkon River. A national park is due to be built adjacent to the wetland with green pools and a freshwater lake extending over an area of 30 dunams - 7½ acres - that will provide fishing and boating. After its rehabilitation the river will attract many fish and birds and residents will be able to enjoy walking and cycling along both banks of the Hadar River.