The amount of rubbish generated in Singapore last year - more than 7.6 million tonnes - is enough to fill more than 13,000 Airbus A380 superjumbos to their maximum takeoff weight.

And the country's one active landfill at Pulau Semakau is expected to top out by 2035.

"We, mankind, are facing a war, the war between us and the waste we generate," Dr Sun Xiaolong declared to some 100 delegates crowded around the National Environment Agency (NEA) pavilion at the CleanEnviro Summit yesterday.

Dr Sun, managing director of start-up company Zerowaste Asia, was speaking at the Innovation Pitch organised by the NEA, where local and overseas start-ups showcased their waste-management technologies at the Marina Bay Sands Expo and Convention Centre.

Zerowaste Asia has spent five years engineering special chemicals to remove heavy metals from different kinds of waste in a simple, cheap and effective way.

It also recycles the detoxified waste into materials suitable for land reclamation and construction.

The economic potential seems huge. Of the 1,800 tonnes of incinerated waste going to the landfill here every day, 1,500 tonnes is recyclable, said Dr Sun. The company already has projects under way in China and has plans for further regional expansion.

Other start-ups on the list were no less impressive.

For example, BlueRen has patented a process for turning plastic waste into carbon nanotubes for strengthening concrete, while Envichem Technologies uses recyclable chemicals to recover high-purity metals from hazardous waste.

Meanwhile, other outfits are trying to reduce energy consumption and waste generation in the first place by using smart systems.

Take British start-up Winnow, which has developed a system to track the amount, location and value of food waste in kitchens in the hospitality sector.

Its managing director Maxime Pourrat said: "Why not try to go upstream and understand where the food waste occurs, and how we can reduce it before we have to find a solution to recycle?"

Many of yesterday's participating start-ups are looking for larger companies to invest in their technology.

NEA chief technology officer Patrick Pang said partnerships between small start-ups and big companies are a way forward. "They (big companies) get their ideas from smaller companies like these, and smaller companies get the big break sometimes from not just the Government but also from big companies," he said.

"It takes a marriage of both worlds."