Heavy rain brings silver lining

January 19, 2013 by Ahuva Bar-Lev
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The stormy weather in Israel last week caused a lot of damage but also brought great blessings, filling the reservoirs, and making the waterfalls rush and the ravines overflow.

The Kfar Saba filter

The Kfar Saba biofilter

In Kfar Saba, over 230 mm of rain fell during the current storm within seven days, almost half of the annual average. There is a biofilter operating in this city, the first to harvest urban floodwater, treat it biologically, and reintroduce it into the groundwater.
“Floodwater all over Israel is now flowing in the streets, amassing pollutants and draining into the sea,” explained Yaron Zinger, Director of the Biofilter Project in Israel. “Our goal is to turn this nuisance into a resource, to harvest the water, treat it and utilize it. We see every street as a pipeline, from which we can take the water, purify it and use it for various purposes – irrigating parks, agriculture, washing and channeling into our streams.”

The Kfar Saba Biofilter is a joint venture of KKL-JNF Israel, JNF Australia, Monash University in Melbourne, the Kfar Saba Municipality, the Urban Water Association, the Israel Water Authority and Mekorot.

In the course of the recent stormy weather, hundreds of cubic meters of water were introduced into the groundwater after being treated in the biofilter. Beyond prevention of wasting valuable water, the facility also eases the urban drainage system and assists in preventing floods. The water gathered in the biofilter is reintroduced into two places, a nearby well and a system 90 meters deep that conducts the water directly into the aquifer. The facility has a capacity of treating 5,000 cubic meters of water annually.

The upper layer of the biofilter is covered with plants that assist in purifying the water. The lower layers are not aerated, and they foster bacteria that flourish in a low oxygen environment. These bacteria promote processes that purify the water further. This complex system efficiently purifies a variety of pollutants such as heavy metal particles, organic materials and oils. Regular tests reveal that the treated water quality is almost potable.

Visitors to the site may not realize that they are in a water treatment facility. They might think it is a pretty pool landscaped with green grasses. This is another advantage of the biofilter – the landscaping, which may even lower the hot temperatures in the summer, because of the water and the vegetation.

Of course, if there is to be a significant change, a solitary experimental facility in one city is insufficient. KKL-JNF is already planning to construct two more biofilters next year, in Ramla and in Bat Yam, which will see how biofilter technology works in different localities. In Ramla, a great quantity of water will be harvested from a major intercity highway – Highway 40; and in Bat Yam there will be a biofilter in a residential neighborhood, which will address the needs of a dense urban population.

These biofilters will not have plants but will rather have layers for absorbing pollutants. The modular systems will be underground in limited areas that do not need irrigation, and they will work with high output. This method is suitable for densely populated areas where there is no empty public space.

The biofilter is part of a greater scheme known as Water Sensitive Cities, a new applied multidisciplinary science in which KKL-JNF participates. The goal is to find innovative ways to manage urban water economy for the benefit of the residents of the city in an efficient and sustainable way.

Hoping to apply this approach in Israel, a research center was founded with experts from the Hebrew University, Ben Gurion University, the Haifa Technion and the Monash University of Melbourne, with the support of KKL-JNF Israel and Australia. These experts explain that planning of water sensitive cities aspires to respond to the uncertainty related to climate change and to the future necessities of various regions.

“The goal is to find ways to take maximum advantage of the limited water sources available,” said Joe Krycer, JNF Victoria National Consultant.

Climate changes all over the world indicate that there are periods of intensive rainfall, so even if the same amounts of annual rainfall occur, much of it goes to waste. The more cities and roads constructed, the more areas there are where the rainwater cannot penetrate to the groundwater.

“Our aim is to see how we can trap the rainwater in the cities and utilize it for the benefit of the residents,” said Krycer. “In order to achieve this goal, it is not enough to develop suitable technologies. We also have to raise the awareness of the residents, invest in education and, later on, promote suitable legislation.” Krycer said that JNF Australia will continue promoting the issue, since Australia is one of the leading countries in the world in the field of urban water reclamation and related research.

“A good relationship is based on mutual advantage,” concluded Krycer, “and there is no doubt that Australia can learn a lot from Israel in the field of water reclamation in rural areas, so this is definitely a win-win situation.”

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