In the scorching heat of Xiaoshijiazhuang Village, bare-chested Ma Chen weaves through mountainous heaps of old home appliances: His job is to turn trash into treasure.

Ma has four e-waste processing workshops; two dealing with plastics and motherboards, and two more extracting copper and aluminum.

"E-waste is very profitable," Ma says. He disposes of nearly 30,000 washing machines each month at a net profit of up to 90,000 yuan (14,500 U.S. dollars).

Forty-three kilometers away from downtown Shijiazhuang, capital of China's Hebei Province and one of China's most polluted cities, Xiaoshijiazhuang has been extracting profits from e-trash for two decades. About 40 households are involved in the recycling and dismantling business.

China's affluent consumers are constantly upgrading their electrical and electronic goods and how to handle old products that contain dangerous metals is a real problem.

The United Nations Environment Programme says China produces 2.3 million tonnes of e-waste each year, the world's second biggest producer of this kind of trash after the United States. By 2020, about half of the world's e-trash will come from China.

Driven by huge profits, the semi-illegal industry has grown into a fully fledged pillar of the economy in villages and suburbs of big cities. Beijing alone has 300,000 people processing e-waste.

Scavengers sell e-trash to Naizifang Village in Beijing's northern suburb, which has gradually replaced villages like Dongxiaokou and Houbajia as Beijing's e-waste center.

"We want circuit boards from electrical and electronic goods like laptops and cell phones," says Guo Yuanxiong, a migrant worker in the village. "We can extract 99 percent pure gold from the boards. It is shocking, right?"