HANGZHOU - More Chinese universities have joined a program that encourages the recycling of cardboard used for packaging billions of items dispatched after the country's annual shopping spree on Nov 11.

According to the Cainiao Network, Alibaba's logistics arm, more than 100 universities across China have set up recycling points on campus for students to recycle cardboard boxes.

China's e-commerce operators dispatched 1.35 billion items after the Singles' Day shopping bonanza, up by 25.12 percent year on year, according to the State Post Bureau.

Nearly 20 percent of consumers were aged under 23, according to Alibaba.

"Each year, the number of packages has been almost doubling at universities," said Pu Hao, head of a Cainiao distribution center for Zhejiang University City College (ZUCC) in Hangzhou, which joined the program earlier this year.

Pu said the center has handled more than 6,000 packages per day in the days following Nov. 11, doubling the number during off-peak season.

"Around half of students recycle their boxes, and I expect the number to grow in the future," Pu said.

According to Cainiao, a total of 5,000 recycling points had been set up in communities in and around 200 Chinese cities for Single's Day this year.

In the future, these recycling points will be permanent and the company will offer incentives such as online credit to consumers for encouraging an environment-friendly lifestyle, Cainiao said.