For squeaky-clean Singapore, even the local dump is an eco-park with lush green walking trails and migratory birds.

That is because Singapore buries only a fraction of its trash.

This nimble, wealthy city-state crammed on an island 3½ times the size of Washington, D.C., sends only 2% of its solid waste to landfill, burns 38% of it to generate electricity and recycles the remaining 60%.

It’s a model that other cities would do well to emulate. Cities world-wide generate about 1.3 billion tons of solid waste a year—an amount that is expected to reach 2.2 billion tons by 2025, driven mainly by lower-income countries, according to the World Bank.

Perhaps nowhere are the challenges of waste disposal felt as keenly as in Asia’s megacities. In Manila, a city of 12.9 million people, the Smokey Mountain landfill is one of the largest in the world and home to thousands of scavengers who daily are exposed to fumes and toxins. Mumbai, population 12 million, regularly runs out of landfill sites, while Jakarta, 10.3 million, struggles literally with rivers of garbage. Last year, Bangkok and its 9.3 million people were blanketed by smog for weeks when the Thai capital’s landfills caught fire.