Rishon Lezion, Israel
16,000 m3 of sludge per day
The Shafdan is the largest wastewater treatment plant in Israel. The plant treats and disposes of wastewater from an extensive, densely-populated area that includes industrial zones, workshops and businesses in 11 cities and towns including Tel Aviv. The total served population is more than 2,000,000 people. An undesirable by-product of the wastewater treatment process is sludge, the microbiological mass that is created as a result of the decomposition of organic material in wastewater. Sludge is a nuisance to the environment since, barring expensive treatment, it contains active bacteria and pathogens, and its foul odor repels humans but attracts insects.
The Shafdan system receives approximately 400,000 m³ of wastewater each day that produce about 18,000 m³ of excess sludge per day at the end of the treatment process. The excess sludge was previously disposed of at sea via an 11 km outlet (5 Km into the Mediterranean). This is was the largest marine pollution contributor in the country. There was a need to treat, stabilize, dry and dispose of the sludge in more efficient and ecological manner.
The solution to put an end to this pollution is processing the sludge not only to non-toxic and non-polluting levels, but so that it can be used as fertilizer, since this provides a suitable environmental, social and economic return. This solution is was based on the construction of anaerobic digesters and pasteurization tanks that allow treatment of the sludge to a level defined in the regulations as Type A sludge (to be spread on farmlands).
The economic return is further enhanced by burning the methane gas emitted in the digestion process to heat water into vapor, which will turn turbines in a co-generation plant, to produce 11 MW of electricity. This power plant, which uses sludge as its source of energy, will be the largest of its kind in the world. Shtang has constructed these digesters and tanks, installed piping, electro-mechanical, instrumentation & control equipment and commissioned the facility.
Upon successful completion of the project by Shtang, the Shafdan wastewater treatment plant recycles 100% of its wastewater and sludge and became a model for other treatment facilities in Israel while ensuring a clean marine environment.