Exhaust filter virtually eliminates diesel PM2.5

Device reduces harmful emissions by 95 percent

A technology that can help substantially reduce the most harmful emissions of diesel vehicles was recently developed by the Hefei University of Technology.

Liu Yi, a professor at the university, announced on April 11 that he and his team have developed a diesel particulate filter that can eliminate more than 95 percent of PM2.5 pollutants from diesel-fueled vehicle emissions.

PM2.5 refers to particulate matter smaller than 2.5 millimeters in diameter, which can deeply penetrate into human lungs, potentially causing lung cancer.

With the added ability of reducing noise, the filter covers the exhaust pipe and can be recycled, said Liu, a US-educated scientist who came back to China in 2008. He founded Anhui ActBlue Co Ltd while teaching at HFUT.

Liu said China's total amount of PM2.5 from vehicle emissions in 2011 was about 621,000 tons, and diesel particulate matter accounted for 84.5 percent. PM2.5 accounts for a major part of auto emissions.

Deteriorating air quality has become a concern in many Chinese cities in recent years as the number of cars on the roads has skyrocketed, said Liu.

He cited statistics that found the deaths of 25,000 Chinese were linked to auto emissions in 2008, and Beijing recently made headlines worldwide due to record levels of PM2.5.

Zhu Zhiqiang, director of the research center on vehicle emissions at ActBlue, said the working principle of the filter is to block the particles and process them again before emitting them into the air. After burning them for the second time, the particles will become harmless carbon dioxide.

Zhu noted that technologies for lowering diesel vehicle emissions are harder to develop and more expensive than solutions for gasoline-engine cars.

"The ActBlue product represents a leading technology in the country, and it is applicable in the domestic market because of the high sulfur content and poor quality of local diesel," he said, adding that "the price of the filter is relatively high because it contains expensive metal".

Currently, the product retails for 50,000 yuan.

Zhu said that if this technology were adopted on Anhui's fleet of around 10,000 buses, PM2.5 levels could be reduced by nearly 1,000 tons annually, leading to a substantial improvement in air quality.

Another new technology developed by Liu's team is a selective catalytic reduction system that can be used in a variety of autos to decrease nitrogen oxides emission by more than 85 percent, Zhu said.

"The automotive industry is a pillar industry in Anhui, and the new technologies developed by Liu will be of great significance for upgrading the industry and improving the environment," said Li Lian, Party chief of HFUT.

The ActBlue particulate filter is now being used in buses in Chizhou and Fuyang cities in Anhui for trial operations, said Zhu.

Founded in 2009, ActBlue now has the capacity to produce 20,000 sets of diesel particulate filters and 200,000 sets of selective catalytic reduction systems annually.