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2015 International Conference on Mercury Pollution Prevention and Control, Beijing, 8-9 December

Stepping out of the hotel into a “Code Red” pollution warning level, and breathing in air that could almost be described as “crunchy”, was a stark reminder that China faces a huge challenge in terms of pollution control. But the majority of the pollution in Beijing is from cars and industry. The coal-fired power plants that we were meeting to discuss have long been relocated outside the populated city centre. China has made incredible progress in terms of cleaning up its coal-fired utilities; the country has amongst the youngest, cleanest and most efficient coal fleets in the world. Mercury emissions from coal-fired utilities, the topic of this week’s conference, are reported to have peaked in 2010. However, the sheer growth in the coal sector means that the emission reductions achieved do not reduce total emissions to below a level of concern.

The current emission limit for mercury from coal-fired utilities is 30 micrograms/m3 – a level easily achieved considering the co-benefit mercury reduction effects of the flue desulphurisation (FGD) and selective catalytic reduction (SCR) which are in place on almost all Chinese plants (92% and 83% of the fleet respectively). For China, it is the cement sector which is emerging as the new cause for concern. Mercury arrives into the cement production process via coal fly ash as well as via other raw materials. According to Shuxiao Wang, a professor at Tsinghua University and one of the meeting organisers, the construction sector in China is now by far the largest driver of mercury emissions in the country. Reducing emissions from such an intrinsic part of the country’s growth poses a significant challenge.

Dr Yangzhao Sun of the Ministry of Environmental Protection (MEP), gave a summary of how China plans to comply with the Minamata Convention on Mercury. China has not yet ratified it and the convention is unlikely to move towards official ratification until 2017. However, the willingness of China to be one of the early movers under the convention, considering its position as the largest national contributor to global emissions, sends a strong and positive message to other countries who may consider the Convention too much of a challenge.

The Chinese MEP has demonstrated its commitment by establishing a whole new department to deal with the issue – the Mercury Convention Implementation Division (MCID). MCID has produced significant work on all areas of the Convention, from gold mining and mercury in products through to emissions from coal combustion. From Dr Sun’s summary it would seem that life cycle management, of mercury in products and waste through to disposal and potential site contamination issues, is the biggest challenge for China. Relatively speaking, reducing mercury emissions from coal-fired utilities is “do-able” – the technological means are available. There is the suggestion that the 30 microgram/m3 limit for mercury will be reduced to 10 micrograms/m3 within the next five years. However, like their US counterparts, Chinese utilities are beginning to argue that costs for compliance with stricter standards are becoming prohibitive.

Whilst the proposed new 10 micrograms/m3 value represents a significant tightening of the current limit, it does not actually require much of a change in control requirements – many plants will be able to achieve this lower limit without additional control technologies. This will mean that emissions may not be reduced as much as could be achieved with more targeted mercury control. Whilst this could be seen as disappointing – China could set limits closer to those in the USA – there are other issues to consider. The cost would be huge. And, judging by the material flow of mercury from sources to emissions in China, focus on the use of mercury in products, in contaminated sites and from the rapidly growing cement sector, could be more important for the country’s overall mercury reduction plan. Polyvinyl chloride manufacture, a unique and significant source of mercury emissions in China, remains a relatively uncontrolled source of emissions which could be targeted for control. And, amazingly, China remains one of the few remaining countries in the world where you can actually still buy mercury, by the kilo.

The meeting was well attended by Chinese government, academia and industry. There were plenty of US delegates too, mostly from companies offering mercury control options. At one point, a value of 10-15% potential market penetration of activated carbon in China was mentioned although no-one could agree on from where this figure had appeared. It could represent the remaining plants without FGD and SCR systems who could use activated carbon as a multi-pollutant control option. For the majority of plants, fitted with FGD and SCR, oxidant treatment could offer a more affordable flue gas polishing option, should the emission limit for mercury be tightened further in the future.

One interesting fact that emerged during the event was the fact that, counter-intuitively to what would be assumed by those who are concerned about mercury in the human diet, the largest source of mercury in the Chinese diet is actually rice, not fish. Although the Chinese diet is high in fish and this is commonly the largest source of mercury intake, the overfishing of the Chinese coastal waters means that the majority of seafood ingested is too young and too small to contain significant sources of mercury. Which was great news in one sense, as Beijing has some really wonderful fish restaurants.

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