Water. desalination + reuse

RESERACH Seawater desalination in Israel and its environmental impact _________ Nurit Kress and Bella S Galil, Israel Oceanographic & Limnological Research, National Institute of Oceanography, Haifa, Israel. ___ Editor���s Note: Until recently, very little information had been published about the effect of seawater desalination plants on the marine environment, overlooking, for instance, the discharge of chemicals in the reject brine. The plants at Ashkelon, Israel, and Perth, Australia, have been among the first to look at this aspect. This article looks at two working Israeli seawater reverse-osmosis plants, Ashkelon and Palmachim, located on the Mediterranean coast. They have contrasting discharge methods, which allows a closer look at the environmental effects. Around 48% of Israel���s brine discharges will be within 40 km between Ashkelon and Palmachim The Ashkelon desalination plant THREE SEAwATER reverse-osmosis (SWRO) desalination plants located along the Mediterranean coast of Israel currently produce close to 300 million m3/year of desalinated water, around 17% of the country���s freshwater needs or about 40% of its domestic and industrial use. Seawater desalination is expected to increase to 765 million m3/year by 2020, supplying 30% of the country���s freshwater 1. The two large plants Ashkelon and Hadera, each with a capacity of around 120 million m3/year, are adjacent to power stations and dispose of the brine at the shoreline, next to or mixed with the stations��� cooling waters. The salty and warm mixture disperses mostly at the surface 2,3. The smaller plant (Palmachim, with a capacity of about 45 million m3/year) discharges the brine through a 1 km marine outfall (water depth 9 m), and the brine disperses near the bottom 4. DiScharGeS overlooKeD Until recently, the extensive literature on desalination did not address the environmental impacts associated with the | 26 | Desalination & Water Reuse | February-March 2012 process, but focused on plant planning and construction, operation and energy cost. The fact that desalination, including RO, uses chemicals in the process (ie, coagulants, biocides, neutralizers, antiscalants, cleaning solutions and pH and hardness adjustors) that are discharged to the environment was overlooked. It was assumed that when properly engineered and constructed, brine discharge was environmentally safe. When the environmental aspect was addressed, it was descriptive with little quantitative data. An example is the Lattemann and Hopner (2008) study 5, which followed an article in D&WR (August/September 2007, pp 36-44) and a paper at the International Desalination Association���s conference in Maspalomas, Canary Islands, in September 2007. The number of published articles with actual measurements of effects in situ or in lab experiments is small and limited in scope and time, eg, Roberts et al (2010) 6. Most of the few publications emphasize the effects of salinity on the benthic communities, and those are site- and organism-specific 7-13. Recently, the effects of the discharges at Ashkelon on seawater

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