Energy, Environment, Middle East/Africa, Integrated Resources Management, Smart Energy, Water Reuse
Energy + Water
Maximizing Renewable Energy in Large-Scale Water Reuse
Israel taps into anaerobic digestion and cogeneration
In Israel, where rain falls only in the winter, 75 percent of wastewater is reused. The demand for water exceeds yearly rainfall, and water reuse is vital to the country’s economic growth and prosperity. In its arid region and throughout the world, Israel has established itself as a leader in water reclamation.
Producing power from these cogeneration units offsets the need to purchase electricity. They will replace up to 70 percent of the power needed to run the facility.
The Shafdan wastewater treatment plant, the country’s largest wastewater treatment facility, treats and reclaims water for 2 million people in Tel Aviv and 22 cities and towns throughout central Israel. “Mey Ezor Dan” Cooperative Agricultural Water Society LTD (MED), which owns and operates Shafdan, is upgrading the 80-million-gallon-per-day facility to reclaim more resources and accommodate increasing flows.
To maximize renewable energy—and minimize waste created at Shafdan—the expanded plant will incorporate world-class technology, including a staged thermophilic anaerobic digestion and cogeneration facility that will beneficially use biosolids produced from sludge. The project is an important step to end disposal of sludge into the Mediterranean Sea.
MED partnered with CDM Smith for design and on-call construction services for the facility, which will be built by local construction companies. Design was completed in 2012, and construction is underway. The staged thermophilic digestion technology recommended by CDM Smith to produce Class A biosolids—incorporating a waste-to-energy component—reduced costs by $50 million.
The updated 110-million-gallon-per-day plant will accommodate increased wastewater flows through 2030, and include a 310-dry-tons-per-day anaerobic digestion facility and an 11-megawatt cogeneration facility. This new bioenergy facility is part of a progressive, land-based biosolids management program that will beneficially use sludge from the plant, produce Class A biosolids for agricultural use and generate electric power and heat. The program will also include a new sludge thickening and dewatering facility and new headworks and primary sedimentation facilities.
The new bioenergy facility will consist of eight anaerobic digesters with a volume of 13,200 cubic meters each—among the largest in the world. The facility will also include the world’s largest staged-thermophilic anaerobic digestion process. The 11-megawatt cogeneration system will consist of eight internal combustion engines with an electrical and thermal capacity of 1.4 megawatts each. These engine-driven generators will provide enough heat and power to run the anaerobic digester facility and power for the rest of the Shafdan facility. Producing power from these cogeneration units offsets the need to purchase electricity, replacing up to 70 percent of the power needed to run the facility. Meanwhile, there will be significant cost savings, particularly during the on-peak times when electric rates are high.
Setting a new standard
The innovative project design for Shafdan had to incorporate a wide array of considerations—from the budget for the expansion and operating costs, to environmental regulations and even the facility’s aesthetic appearance. As a result, the updated plant will deliver a range of economic, operational, social and environmental benefits in the region. For example, by introducing an efficient, sustainable system for energy recovery, the plant will lower costs, with savings ultimately passed on to rate payers. The methane gas released during anaerobic digestion will be used for energy production in a combined heat and power generating facility, saving approximately $50,000 per megawatt.
In addition, the project will achieve or surpass all environmental compliance requirements, including air emissions. Because the facility will obtain much of its power from renewable energy that it generates, the upgrades will reduce air emissions and subsequent damage from greenhouse gasses. Beneficially using sludge protects the waters of the Mediterranean and its wildlife and fish from pollution. And the high-quality Class A biosolids produced at Shafdan will provide a soil amendment that can be widely used for agricultural purposes, from fertilizing crops and preserving green areas to support the region’s economy.
Because the facility is located near a growing city and a military base, it was also important that Shafdan continue to be a good neighbor to surrounding communities. The plant will be attractive, and provide visual screening. Additional features at the plant will ensure that odors and noise are minimized and controlled.
Staged thermophilic anaerobic digestion with cogeneration is a continuous, relatively easy to operate bioenergy technology to produce Class A biosolids, heat and power. This project sets a new standard for wastewater treatment, beneficial use and cogeneration facilities both in scale and technology. Construction is scheduled to be finished in 2015, and the facility is expected to serve as a model for other similar projects in Israel and throughout the world. Yuval Sela, chief engineer at MED, adds, “At MED, we are committed to developing our organization into a role model for similar utilities around the world. The digester facility project now under construction will be a great project that could not have been built without CDM Smith’s dedicated focus on ensuring its success.”