"Emerging pollutants in waste water, generated by synthetic material such as drugs and cosmetics, are also bothering environmental experts both home and abroad," according to Yu.

He said that these pollutants are "invisible enemies" which are hard to trace and eradicate in waste water treatment. Once they are discharged into nature, they will be taken in by people via food or water and accumulate in bodies, impacting future generations.

In 1998, Singapore initiated the NEWater project to treat waste water using dual-membrane and ultraviolet technologies in addition to conventional processes, to solve the country's reliance on water imported from Malaysia.

The project received great responses from the world and wrote a new chapter in turning waste water into drinking water, having profound meaning for global waste water treatment, according to Yu.

"Therefore, we are making efforts to build a concept plant in China to tackle the problems of treating urban waste water, aiming at stricter standards of discharged waste water and lower energy consumption," he said.

The Concept WWTPs' improvements will include increased recycling of resources such as nitrogen and phosphorus, two elements that must be separated from waste water but are needed to add nutrients to fertilizer; while the plan is for the plants to be "community-friendly" near households.

The experts are also in search of methods to fight Yu's "invisible enemies."