Multi-pollutant scrubber does the job

On 8 February the American Bureau of Shipping (ABS) issued a Statement of Fact on the performance of the CSNOx system showing reductions in emissions of sulphur dioxide (SO2) by nearly 99 per cent, reducing nitrogen oxides (NOx) by around 65 per cent, and carbon dioxide (CO2) by about 77 per cent. The system is installed on a 100,000 dwt Aframax tanker burning heavy fuel oil (380 cSt) with a sulphur content of 3.64 per cent.

According to its producer, the Singapore-based company Ecospec, in the CSNOx system freshwater or seawater is first fed into an ultra-low frequency electrolysis system to make it alkaline and ready for scrubbing. The alkaline water is then pumped through the exhaust stack to scrub the flue gas. The treated water is highly reactive and removes SO2, NOx and CO2 through absorption. The removed pollutants are said to be converted into harmless substances found naturally in the water. After scrubbing, the scrubbed water may pass through a solid-liquid separator to remove solid particles. The water recovered will then undergo treatment to meet the discharge water standard. If the water supply is limited, the scrubbed water can be further treated and recycled back to the scrubbing process, reducing the amount used.

Source:, 25 February 2010.

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