A British architect has unveiled plans to build the world's tallest towers in the central Chinese metropolis of Wuhan – two adjacent kilometre-high spires that could help purify the city's polluted air and water.

London-based Chetwoods Architects presented the Phoenix Towers plans to Wuhan's mayor about six months ago, said its chairman, Laurie Chetwood. Pending official approval, the practice hopes to break ground by the end of the year.

According to its website, the project will be "an iconic landmark within an ambitious environmental masterplan for Wuhan", a city of 10 million people on the Yangtze river. The project will span 47 hectares and cost an estimated £1.2bn.

Computer renderings published online show the steel and concrete towers glowing like hot pink, space-age Eiffel Towers, their buttresses spanning an island in the middle of a lake.

"This is a big iconic statement that says 'this is Wuhan, look at us, we're here,'" Chetwood said. "But it's an environmental statement as well. It would help to improve the area."

The towers have been designed to incorporate elements from traditional Chinese culture. Together, they represent the phoenix – "feng" and "huang", a pair of mythical Chinese birds. The feng, or "male" tower, will supply renewable energy to the huang, or "female" tower, a "softer" space with cafes, restaurants and a 100-storey vertical garden.

According to the website, the towers will power themselves with green energy technologies such as "lightweight photovoltaic cladding", "suspended air gardens" and "waste recycling via biomass boilers". The feng tower will be fitted with wind turbines, and it will use solar power to suck polluted lake water up through an advanced filtration system.

A commercial square at the towers' base will cater to China's growing demand for cultural tourism. "You'll have a French street, a Japanese street, a Turkish street and so forth … to allow people to see the world without necessarily having to leave China," Chetwood said.

He said the firm was working with two Chinese companies on the project – the Beijing-based HuaYan Group and the CITIC Group, a state-owned investment company.

"If you work in the UK, if you come up with anything that's off the wall or slightly out there, you sort of get kicked back," he said. "In China it goes the other way – they ask for a bit more. That's a stimulating experience for a designer."