RACHEL MARTIN, HOST:
Israel is a desert country and as a matter of survival has had to become a pioneer in water technology. Last week, NPR's Emily Harris brought us a story about how Israel is building a desalination plant in San Diego. Today, Emily digs deeper into Israel's water treatment systems for agricultural use and finds that can be kind of a messy job.
EMILY HARRIS, BYLINE: One of the first challenges is wet wipes says Meir Ben Noon, chief tour guide at Israel's biggest sewage treatment plant.
MEIR BEN NOON: You have wet wipes. You love them. It says premoistened, flushable or biodegradable. And you believe that you can throw to the toilets.
HARRIS: Three quarters of the garbage hauled out here is wet wipes.
BEN NOON: Every day, we are doing with 30 tons of wet wipes in our pipes that creating blockage.
HARRIS: Once the big garbage is out, the real cleaning begins. That's done by microbes munching sewage in big ponds outside. But they need air to live, and pumping that air takes energy. So this plant is building a system to trap methane from decomposing microbes known as sludge and use that gas for power.
BEN NOON: The idea is to take the sludge, basically to kill it slowly with high temperature. And the gases coming out from the same process will give power, which is the energy, the electricity that will supply most of this facility.
HARRIS: That's a fairly standard practice around the world, but because Israel uses a much higher percentage of its treated usage for irrigation than any other country, according to Israel's Water Authority, entrepreneurs are also experimenting with new ways to cut the energy bill.
At a small experimental sewage treatment site, I climb above a tank of bubbling brown water with Eytan Levy, CEO of a startup called Emefcy.
EYTAN LEVY: It's being mixed right now for a few seconds. It's stopped.
HARRIS: The bubbling is settling down. It's defusing.
LEVY: And now it will settle. And in a few seconds, you will see that the upper layer becomes clear.
HARRIS: Levy's company is trying to capture electricity from the live microbes as they munch.
LEVY: It starts from the idea that the organic contamination in the wastewater is, in fact, a fuel. Now we spent a lot of electricity getting rid of this fuel. And you ask yourself, why can't we utilize this energy?
HARRIS: He admits it's futuristic, but it's a current issue. Half the water for Israel's farms comes from treated sewage water.
It smells a little bit like rotten eggs out here.
I've traveled to a kibbutz almond orchards south of Jerusalem. Efi Cohen is showing me the communal farm's local sewage treatment plant. It's a big concrete tank with a red pipe going out of it.
Why is the pipe red?
EFI COHEN: Because red - it's not water for to drink.
HARRIS: But it is water for crops. The red pipe dumps into a pond making a frothy foam. The water comes from the toilets, showers, sinks and even chip manufacturing plants of nearby communities. Government regulations allow Cohen to use this water only on some crops.
COHEN: The almond, it's dry, right. Every food, when it dry, you can use this. But I don't allow to irrigate watermelon for the food.
HARRIS: The rule is recycled sewage cannot come into direct contact with food. Soil chemist Benny Chefetz studies pollutants in his lab.
Wow it's bright in here.
BENNY CHEFETZ: Yeah. Those are cucumbers.
HARRIS: Chefetz researchers what happens to drug residues left in treated sewage water used for irrigation. Some, like epilepsy medications, can be found in trace amounts in certain crops. Chefetz says that raises important long-term questions.
CHEFETZ: We have no idea what is the consequences of a two-year-old child that will start to be exposed to those antiepileptic drugs when he was eat cucumbers, carrots etc. for the entire life.
HARRIS: He says it's important to figure out what's safe because using treated sewage water is important.
CHEFETZ: We must continue to irrigate with treated wastewater because there is no future for the cultural activity in places like Israel because there's not enough water, freshwater, high-quality water to support intensive agriculture.
HARRIS: He says that's true around the Mideast now and perhaps in other countries in the future. Emily Harris, NPR News, Jerusalem.
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