Wastewater wonders

Israel is the world’s leading waste water recycler.

Yeroham water plant 311 (photo credit: Avri Kadmon, JNF)
Yeroham water plant 311
(photo credit: Avri Kadmon, JNF)
Next time you flush a toilet in Tel Aviv, take a moment and consider the journey of that flush. The wastewater is treated and then pumped through underground pipes 100 kilometers south to the Besor Reservoir, where it is used to irrigate an orchard belonging to Kibbutz Nirim, whose grapefruits are shipped to supermarkets throughout Russia.
“The miracle of Israel’s wastewater” may sound like a (pretty gross) overstatement, but it’s true: Israel is the leading wastewater recycler in the world. Seventy percent of its sewage, and 100% of the sewage from the Tel Aviv metropolitan area, is treated and reused as irrigation water for fields and public works.
The next country in line in terms of wastewater recycling is Spain, which recycles about 17% of its sewage. “No one uses their water as efficiently as we do,” says Avri Kadmon, the information director of the Development Enterprises Department at the Jewish National Fund. The JNF has been at the forefront of wastewater treatments since the 1990s, building reservoirs and plants that handle about 70 percent of wastewater recycling.
Touring the water recycling facilities in the Negev opens up an incredible new world that very few people tend to think about, and fewer discuss. What happens after I flush the toilet? In Israel, a lot.
You can talk about water recycling using the stark statistics: Each year, the country produces about 520 billion cubic meters of sewage. About 375 billion cu.m. are treated and reused. In the past, 70% of freshwater resources were used for agriculture. Today, that number is down to 40%.
You can also talk about water recycling in terms of the people it affects most: the farmers.
“In the past, every time there was a water shortage, the water was taken from the farmers for domestic consumption,” explains Kadmon. “So the farmers could not plant for the long term, and they had to irrigate fields with annual crops like wheat or corn...When they receive wastewater from a reservoir, they know the amount, they know the quality of the water, and this water is secure. The reliability means they can plant for the long term: Farmers can double or triple their income from the same area.”
Making farming more profitable means more people will turn to farming in the future, instead of the industry dying out. This is essential for the peripheral areas of the country, which are typically agriculture- heavy areas.
Next time you drive through a rural area, keep your eye out for bright purple pipes in the fields. This purple color means the pipes deal with recycled water. Read on for a look at what exactly happens to wastewater after it leaves your house.
HOW DOES A sewage recycling plant work? Take a tour of the Yeroham plant.
The Yeroham water treatment plant is one of the most modern sewage treatment facilities in the country. Yeroham, a Negev town of 10,000 with 15 factories, wants to expand, but the water shortages have stymied construction. The treatment plant opened in 2005 and today recycles 100% of Yeroham’s sewage. The entire treatment process takes between 18 and 36 hours on average, treating 2,000 cubic liters per day. “In a town like Yeroham, in the middle of a desert, every drop of water is gold,” says engineer Adam Strauss, who has worked at the plant since its inception.
1. The wastewater runs from the town to the plant, a few kilometers away, in pipes that are always sloping slightly downward. This means gravity does all the work in getting the waste to the plant.
2. Once the wastewater reaches the plant, it’s pumped above ground to the highest point in the plant. The plant is set up so that the processes also take place on a downward slope, meaning that pumps are used only once to maximize energy efficiency. “We want to use the minimum amount of energy for every drop of water,” says Strauss.
3. The wastewater goes through a series of physical barriers. These bar screens stop solids and large waste that cannot be recycled from entering the reactors. The plant can remove organic matter only, so any inorganic matter that finds its way into the wastewater is removed at the beginning.
4. Next, the wastewater enters reactors, which look like massive cement barrels the size of a small swimming pool. These reactors grow bacteria that eat the organic material in the water. Each treatment plant has its own unique strain of bacteria that is particularly well adapted to the organic waste of a geographic area.
5. After a few hours in the reactor, the plant operators let the water settle. The bacteria are heavier and settles to the bottom. The bacteria, referred to as “sludge,” go back into the reactor for the next batch, while the water is transferred to the tertiary cleaning area. At this point in the process, the water could be used for agricultural purposes and public irrigation. But a 2005 law requires tertiary treatment at all plants to further clean the water, meaning the water is safe for consumption if someone accidentally drinks it.
6. In the tertiary treatment, the water is pushed through sand. The pressure and the sand act to purify the water. In Yeroham, chlorine is also added twice, once before it enters the holding reservoir for the tertiary treatment, and again before it is pumped back to the town for agriculture.
7. The water exits the plant as clear and clean as water straight from the tap. Its chemical makeup is checked by a computer every five seconds to ensure that no unsafe wastewater is exiting the plant.
Putting a cup of recycled water next to a cup of tap water, it’s impossible to tell which is which. If the plant had a desalination area, the water could reach levels cleaner than what comes out of the tap. “I’m not going to try to convince you to drink this,” Strauss says. “There’s a psychological barrier, a person should not drink sewage.” There’s also no need to drink recycled sewage, he argues. “There is enough water to drink in Israel,” Strauss says. “The problem is that we’re using drinking water for irrigation.”