Runner-up ReCube's business model is simple: it rents reusable tableware to restaurants for takeaway orders.

Users earn rewards on ReCube's mobile app if they opt for the alternative tableware, and they can return them to any eateries in its network even without washing them.

The tableware has been used 6,400 times since ReCube's launch in January and the start-up has teamed up with 32 restaurants with about 3,000 pieces in use.

Reusable tableware is better than paper straws and cutlery which soften rapidly in liquids, and probably cleaner as well, says cofounder Kelvin Tsui Ka-hei.

The boxes and cups are made of polypropylene, which is durable and heat-resistant, and each tableware can be used between 500 and 1,000 times.

To ensure hygiene, ReCube only teams up with restaurants that have proper sterilization facilities mandated by the Food and Environmental Hygiene Department.

Partner restaurants will also be placed on the list of the government-initiated Bring Your Own Containers Eateries scheme.

The start-up aims to cover all restaurants in the city in two years and Tsui is confident about meeting this target, as the shift to reusable tableware can reduce expenses for restaurants.

However, he admits it won't be easy to change deeply ingrained habits and conceptions, and his concept will need to be extensively promoted for it to succeed.

Another challenge is to find more sustainable revenue sources. ReCube currently charges restaurants a one-off fee for renting the tableware and diners play nothing if the utensils are returned within seven days.

Tsui says ReCube is currently supported mainly with funds from various programs, but it will try to team up with some major corporations to ensure its future.

Backed by business advice from the Hong Kong Social Enterprise Challenge and the Hong Kong Baptist University, Tsui hopes that ReCube will continue to contribute toward the government's goal of making Hong Kong plastic free in the future.

THINKING OUT OF THE BOX: Kelvin Tsui.

Takeaways get greener, cleaner