Four new bottle collection machines installed in two subway stations have received more than 900 bottles in their first six days of operation, but some people complain the machines are impractical and a waste of time.

The four machines were designed and operated by Beijing Incom Resources Recovery Recycling Company and installed in Shaoyaoju and Jinsong stations along Line 10. The recycled plastic bottles are inserted in the machine and crushed, then collected for further recycling.

Zhang Weidong, a marketing staff member of the company that oversees the machine in Shaoyaoju station, said that most users are seniors living in nearby apartment compounds.

The machines offer ten fen for large bottles and 5 fen for small ones. The money is credited to the user's subway card - if people have patience to wait several minutes.

The machine tries to read the barcode of each bottle, and also must connect to the subway system's database to credit users' subway cards.

"This is supposed to be environmental friendly, but how much electricity was lost in our repeated efforts to insert the bottles and receive credit on our subway cards?" said a passenger surnamed Du, who used the machines in Jinsong station with his girlfriend.

Zhang explained that the machines are only the first-generation products, and will be improved. "The machines use 3G [mobile phone network] signals to credit the subway cards," said Zhang.

The machines pay about half the rate offered by existing centers that cater to bottle collectors.

An expert at the environmental NGO Green Beagle says the machines may promote awareness but the bottles would end up being recycled anyway.

 "Even if people put the bottles in public garbage cans or their own home waste bins, the bottles will be dealt with the same way," he said.