A worker packs the electronic waste after dismantling at one of the recycling processing plants in southwest China. [Photo/China Daily]

According to the Ministry of Industry and Information Technology figures, about 400 million old mobile phones are discarded every year. Only 1 percent of them are recycled.

To raise that recycling figure, firms such as Aihuishou offer a transparent trading system that guarantees relatively high prices for used products.

A user can choose different trading methods like making an appointment for a door-to-door service, visiting the offline store or mailing mobile phones directly to Aihuishou, Chen said.

The company has set up more than 50 offline stores in Beijing, Shanghai, Guangzhou and Shenzhen, offering door-to-door testing and recycling service.

The lower-end mobile phones valued at 5 yuan (80 US cents) to 20 yuan, which account for 20-30 percent of recycled phones, will be handed over to Green Eco-Manufacturer, a Shenzhen-based electronic waste recycler, for metal and component extraction and environmentally friendly destruction.

On the other hand, high-end phones, which account for 20 percent of recycled phones, are resold as used goods after professional processing. Even warranty is provided.

As for mid-range phones, which account for 50-60 percent of recycled phones, recyclers bid for them, Chen said.

Besides mobile phones, Aihuishou deals in digital cameras, computers and computer accessories. Its trade-in program, involving mobile majors such as iPhone, Samsung and Xiaomi, encourages consumers to upgrade their phones.

Chen believes the phone recycling market has a huge potential for development.

"The updating cycle of mobile phones is usually about 18 months, and we plan to open more offline stores in first-and second-tier cities. We'll further explore the market for second-hand mobile phones valued between 20 yuan and 200 yuan, and make profit by means of disassembling metal parts."

Like Chen, Zhou of Ihuigo.com sees gold in junk. Cheated by a mobile phone recycling vendor, Zhou decided to create an online recycling platform where consumers would never feel conned. "Consumers can check the price and make recycling deals in a safe environment."