In the current study, the environmental performance of the first full-scale combined low-pressure exhaust gas recirculation (EGR) and seawater scrubbing system was investigated thoroughly onboard an LPG carrier operated on high-sulfur HFO. Results clearly show that the chosen approach allows around 70% $$\hbox {NO}_x$$ NO x reduction and simultaneous elimination (98% reduction) of $$\hbox {SO}_x$$ SO x emissions. This would allow compliance both with $$\hbox {NO}_x$$ NO x Tier III and future ECA sulfur regulations, although it would result in minor fuel penalty due to slightly deteriorated combustion (effect of EGR) and increased backpressure (effect of scrubber). The performed chemical analysis of the water samples revealed a fairly good performance of the wash water treatment plant with water samples identified as a good-quality water almost against all measured compounds. The values for pH, turbidity and nitrates were also far below the IMO requirements. However, in terms of certain metals (vanadium, nickel and zinc) and PAHs (fluoranthene and pyrene), the quality of discharge water was somewhat poorer. These compounds also appear to be the main drivers of risk of the environmental damage as was determined by the PEC/PNEC analysis. Here, the sufficient dilution with ambient seawater is essential to bring down the corresponding concentrations to the acceptable levels, although the measured excessive pollution of ambient water in terms of arsenic, copper and molybdenum should be kept in mind. Finally, different sampling procedures (IMO MARPOL and US EPA VGP rules) were practically evaluated providing some ideas for their further improvement, as with wrong sampling the obtained results can be very misleading.

中文翻译：

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通过结合低压 EGR 和海水洗涤来满足未来的海上排放法规

在当前的研究中，在使用高硫 HFO 的 LPG 运输船上彻底调查了第一个全尺寸组合低压废气再循环 (EGR) 和海水洗涤系统的环境性能。结果清楚地表明，所选择的方法允许约 70% $$\hbox {NO}_x$$ NO x 减少和同时消除（减少 98%）$$\hbox {SO}_x$$ SO x 排放。这将允许同时符合 $$\hbox {NO}_x$$ NO x Tier III 和未来的 ECA 硫法规，尽管由于轻微的燃烧恶化（EGR 的影响）和背压增加（EGR洗涤器）。对水样进行的化学分析表明，洗涤水处理厂的性能相当好，水样几乎与所有测量的化合物相比都被确定为优质水。pH、浊度和硝酸盐的值也远低于 IMO 的要求。但就某些金属（钒、镍和锌）和多环芳烃（荧蒽和芘）而言，排放水的水质稍差。正如 PEC/PNEC 分析所确定的，这些化合物似乎也是环境破坏风险的主要驱动因素。在这里，用周围海水充分稀释对于将相应的浓度降低到可接受的水平是必不可少的，尽管应牢记测量到的周围水的砷、铜和钼过度污染。最后，