JINAN - A cargo ship carrying 20 tons of processed waste oil left Qingdao port of eastern Shandong province for the Netherlands Monday morning.

This is the first batch of China's oil refined from leftover cooking oil to be exported and the products will be further processed into aviation fuel for the Royal Dutch Airlines.

Royal Dutch Airlines became the world's first airline company which adopted bio-fuel in June 2011.

The Qingdao-based Fresh Bio-Energy Technology Development Company Ltd sold the oil to SkyBRG, a Dutch bio-fuel supplier, said Zheng Dehua, deputy general manager of the Chinese company.

"The 'non-edible oil' will become bio-diesel oil after the second process. Due to higher costs and other factors, the Dutch company did not purchase our final products," Zheng said.

The Qingdao-based company produced the oil by combining waste oil and fat, including "gutter oil," or discarded cooking oil, after pretreating and distilling the substances, an earlier report quoted Zheng as saying.

The company has a capacity to annually produce 50,000 tons of biodiesel from gutter oil, according to Zheng.