Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel.
Water Res. 2011 Nov 1;45(17):5449-62. doi: 10.1016/j.watres.2011.08.005. Epub 2011 Aug 11.
Global desalination quadrupled in the last 15 years and the relative importance of seawater desalination by reverse osmosis (SWRO) increased as well. While the technological aspects of SWRO plants are extensively described, studies on the environmental impact of brine discharge are lacking, in particular in situ marine environmental studies. The Ashqelon SWRO plant (333,000 m(3) d(-1) freshwater) discharges brine and backwash of the pre-treatment filters (containing ferric hydroxide coagulant) at the seashore, next to the cooling waters of a power plant. At the time of this study brine and cooling waters were discharged continuously and the backwash discharge was pulsed, with a frequency dependent on water quality at the intake. The effects of the discharges on water quality and neritic microbial community were identified, quantified and attributed to the different discharges. The mixed brine-cooling waters discharge increased salinity and temperature at the outfall, were positively buoyant, and dispersed at the surface up to 1340 m south of the outfall. Nutrient concentrations were higher at the outfall while phytoplankton densities were lower. Chlorophyll-a and picophytoplankton cell numbers were negatively correlated with salinity, but more significantly with temperature probably as a result of thermal pollution. The discharge of the pulsed backwash increased turbidity, suspended particulate matter and particulate iron and decreased phytoplankton growth efficiency at the outfall, effects that declined with distance from the outfall. The discharges clearly reduced primary production but we could not attribute the effect to a specific component of the discharge. Bacterial production was also affected but differently in the three surveys. The combined and possible synergistic effects of SWRO desalination along the Israeli shoreline should be taken into account when the three existing plants and additional ones are expected to produce 2 Mm(3) d(-1) freshwater by 2020.
在过去的 15 年中，全球海水淡化量增加了两倍，反渗透（SWRO）海水淡化的相对重要性也有所提高。尽管 SWRO 工厂的技术方面有广泛的描述，但缺乏对盐水排放的环境影响的研究，特别是在原位海洋环境研究方面。阿什克隆 SWRO 工厂（每天 333000 立方米淡水）在海滨排放盐水和预处理过滤器的反冲洗水（含有氢氧化铁凝结剂），就在发电厂的冷却水旁边。在本研究时，盐水和冷却水连续排放，反冲洗排放呈脉冲式，频率取决于进水的水质。确定、量化并归因于不同排放物的排放对水质和近岸微生物群落的影响。混合盐水-冷却水排放物增加了出水口的盐度和温度，具有正浮力，并在表面扩散至出水口以南 1340 米处。出水口处的营养物浓度较高，而浮游植物密度较低。叶绿素-a 和微微型浮游植物细胞数量与盐度呈负相关，但与温度的相关性更为显著，可能是由于热污染。脉冲反冲洗的排放增加了浊度、悬浮颗粒物和颗粒铁，并降低了出水口处浮游植物的生长效率，这种影响随着与出水口的距离的增加而降低。排放物显然减少了初级生产力，但我们无法将这种影响归因于排放物的特定成分。细菌生产力也受到了影响，但在三次调查中的影响方式不同。当预计到 2020 年，三个现有的海水淡化厂和另外三个工厂将生产 200 万立方米/天的淡水时，应该考虑以色列海岸线的 SWRO 海水淡化的综合和可能的协同效应。
