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Following successful attempts to increase the use of purified waste water for irrigation, Israel has also started to reuse the remaining sewage sludge.

Some experts contend that the sludge, which is used as fertilizer, presents health risks and say its use should be limited - or even stopped altogether.

About half of the sludge produced in Israel is currently sent out to sea from a waste-treatment plant in the Tel Aviv area. Next week, however, the agency that runs that plant, the Dan Regional Association for Environmental Infrastructure (better known by its Hebrew name Igudan ), will be dedicating a new facility that will enable sludge from the Tel Aviv area to be processed and used for agricultural purposes as well.

Ninety-four percent of the sludge that is not going out to sea is already being reprocessed and used as fertilizer, a new Environmental Protection Ministry report states.

Over the past year about 63,000 tons of sludge has been provided to three treatment plants where it has been processed into compost for agricultural use. The largest of the facilities is in the Jordan Valley.

Until about a decade ago, sludge, which is a byproduct of waste-water treatment, was sent to dump sites or to open areas where it presented an environmental hazard. Sludge can contain disease-causing bacteria in addition to poisonous metals and chemical residues that can disrupt the hormonal system of animals and humans. Because of the presence of these substances, there are experts who caution against the recycling of sludge.

The Environmental Protection Ministry said attention to the presence of hormonal substances in sludge is relatively new and no standards exist. With respect to the presence of poisonous metals, the ministry said the final processed product used in agriculture doesn't contain the metals in quantities that exceed standards.

Demand for the processed compost currently far exceeds supply, the ministry said, so the additional supply that will be produced from the new Tel Aviv area facility is also expected to find customers.