Several containers are neatly placed under the kitchen sink with categorized waste in them. Different-colored waste bins sit alongside the road with signs indicating what garbage they take. Modern-equipped facilities at the clean garbage treatment plant "swallow" different waste and "spit out" sewage gas, electricity and fertilizer.

At the ongoing World Expo 2010 in Shanghai, Xinhua reporters saw many displays demonstrating all kinds of eco-friendly ways to turn waste into treasure.

Malmo, Sweden

At the best urban practice exhibition area, visitors can see clear classification of garbage in every family and every block in the Swedish city of Malmo.

Different trash cans are for different wastes: food waste, glass bottles, paper and cartons, plastic and metal.

After treatment and recycling, classified waste can be used again: food waste to become fertilizer and to produce biogas, offscum to pave roads, used glass and plastic bottles, newspapers and metal containers to be recycled.

According to Yao Shuang, manager of the Malmo exhibition, 77 percent of packaging and newspaper in Sweden was recycled in 2009, and Sweden's goal is to give 35 percent of food waste biological treatment.

Madrid, Spain

Madrid's exhibition area showcases a clear technological process of garbage treatment.

The treatment plant first divides waste into recoverable waste and non-recoverable waste. Some of the non-recoverable waste is used to produce electricity, and the rest goes to the landfill to produce biogas.

The recoverable waste is a total treasure-trove. It is mainly divided into recycle materials and organic matter. After fermentation, composting and maturation, organic matter will turn into fertilizer for agriculture, or be used to produce biogas and electricity.

Recycle materials, such as glass, plastic, metal and paper, can be recycled and made into similar products.

Under scientific and effective waste classification and treatment, Madrid recycles every year more than 120,000 tonnes of paper, 53,000 tonnes of plastic and metal and 38,000 tonnes of glass.

From the garbage, the city produces 306,000 kwh of electricity per year, extracts 70,000 tonnes of organic fertilizer, and reduces CO2 emission by 770,000 tonnes per year.

In Madrid, waste is indeed a treasure.