Recycling food waste

Recycling food waste

Students are learning the need to cut down on leftovers

How much food waste do you produce every day?

In a broad sense, food waste is anything that we dispose of - either during the course of producing, making or eating food. From the meal we could not finish, to the fruit peel or egg shells that we usually throw away, we contribute significantly to the food waste problem.

Every day, Hong Kong produces 3,584 tonnes of leftovers - which make up one third of our overall waste. In addition, organic food waste produces greenhouse gases, such as methane and wastewater, which contain high levels of bacteria. This poses a threat to the environment and our health.

So how can we use new ideas to deal with excessive leftovers?

There has been a growing interest from people to make - and then use compost. This is a way of converting organic waste into useful humus - a substance made from dead leaves and plants by adding micro-organisms such as bacteria and fungi. It contains rich nutrients and can be added to soil to help plants grow.

Creating the humus is a natural way to recycle food waste. Mixing suitable levels of carbon, water, nitrogen, oxygen and micro-organisms allows the effective breakdown of the food waste to produce compost.

Last year, CityU worked with Greeners Action, a charity promoting environmental protection, to collect leftovers on campus and create compost for growing plants at the university. It is good to use leftovers for something positive like compost, which also helps improve soil structure, protects plants from diseases and stops roots and the earth drying out.

Apart from recycling of food waste, non-government and voluntary organisations have become involved in food donation. The Foodlink Foundation collects and delivers unused food in Hong Kong to create a sustainable food-recycling system for disadvantaged people.

A group of university students set up The Leftovers to collect leftovers from banquets.

Food waste can be limited by using science and technology, and social campaigns, but cutting down on leftovers at the source is the most effective option.

Locally, Yaumatei Gardener has published leaflets recommending ways to make new dishes from leftovers.

Innovative recipes use leftover pork to make pork floss and fake shark's fin soup.

Four members of Foodlink Foundation, The Leftovers and Yaumatei Gardener shared ideas on reducing waste with students at the forum, "MaD @ CityU - An Innovation Lab: 10 Ways to Zero Food Waste", set up by Project Flame and MaD (Make a Difference).

The CityU platform, Project Flame, helps improve students' entrepreneurship and social innovation. They can learn how to contribute to society as change-makers, while adding value to their educational experiences.


What is the purpose of compost?

Answer the question about this story and win fabulous prizes. E-mail your answer, your school name and phone number to with "Science" in the subject line.

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