Image caption A food recycling scheme uses discarded vegetables from a wet market to cook food for the unemployed

It is dusk at Hong Kong's Tai Wo wet market and the stallholders are shutting up shop, separating browning bean sprouts and bruised oranges from the fruit and vegetables fresh enough to be sold the next day.

Unlike the waste from most of the city's fresh produce markets, which is dumped in one of three fast-filling landfills, the leftovers from this one are collected by a local food-recycling scheme.

Run by the Hong Kong Confederation of Trade Unions, it uses the discarded vegetables to cook meals for the unemployed. The rest is sent to local farms to be composted.

"We usually collect around 180kg, and around 70% is edible," says Christina Jang, who works for the project in Tai Wo, near Hong Kong's border with China.

"That can feed 60 people."

Buffets and banquets

The metal carts are being pushed by a group of teenagers from a local secondary school.

Equipped with white-cloth gloves, they giggle and squirm as they fill blue plastic boxes with pineapple peelings, green beans and garlic shoots.

A city that loves its buffets and banquets, Hong Kong dumped 3,600 tonnes of food waste a day in 2011.

We believe this process would be profitable, although it depends on the scale Carol Lin, City University of Hong Kong

That is 11% more than in 2010 and the city looks particularly wasteful when compared to nearby countries.

According to figures provided by Friends of the Earth, Hong Kong generates half a kilo of food waste per head daily, compared with 0.36kg produced in Singapore, 0.35kg in Taiwan and 0.29kg in South Korea.

Friends of the Earth has launched a campaign encouraging people cut at least two dishes from the traditional banquets held to mark weddings, business deals and other special occasions. The elaborate meals can stretch to more than 12 courses.

Some two thirds of the city's food waste comes from households, and a third from the city's supermarkets, food stores, restaurants, hotels and schools. But it is food waste from this latter group that is expanding quickest.

Recycling options are few and far between. Most people live in high-rise apartments, with no space for composting and, as yet, there is no city-wide formal recycling for food waste.

The issue has taken on greater urgency as the city's three landfill sites reach bursting point. All three are expected to be full by 2018.

Novel approaches

In this gap, charities, business and scientists are coming up with their own solutions to the city's food waste problem.

Two dozen non-governmental organisations and charities are said to operate food recycling programmes similar to the one at the Tai Wo wet market.

Biotechnology is another alternative, says Carol Lin, a scientist at City University of Hong Kong.

She has pioneered a technique that takes bakery and other food waste and makes succinic acid, a chemical that is widely used in the production of plastics, fabric and other fibres.

"We believe this process would be profitable, although it depends on the scale," she says.

Succinic acid is normally made from petrochemicals, so her bio-refinery offers a potential double benefit - a commercial use of food waste and a way to reduce reliance on finite resources such as oil.

So far, though, no company has been willing to make the 19m Hong Kong dollar ($2.5m; £1.5m) investment needed to build a plant in Hong Kong, where land is scarce and expensive.

Pay as you throw

The government has begun to consider a city-wide solution to mounting levels of leftover food. Recently, it pledged to cut food waste by 10% in three years.

It has also launched a public consultation on charging for waste collection - a strategy that has led to a significant fall in waste disposal in Seoul and Taiwan.

Image caption Hong Kong is trying to raise awareness of food wastage among students

A per-bag charging scheme introduced in Taipei in 2000 reduced domestic waste disposal by 62% and domestic waste generation by 20% over a 10-year period, according to the consultation document.

Taipei also closed refuse collection points and public litter bins to avoid illegal dumping and the scheme's success allowed the country to delay the construction of rubbish incinerators.

It remains to be seen whether famously free-market Hong Kong will be prepared to adopt such charges.

However, a poll conducted by Friends of the Earth in November suggested that 65% of 1,000 people surveyed would be willing to pay a fee, up from 52% six months earlier.

Memorable meal

Back at the wet market, the students wheel their carts of unsold vegetables to a kitchen used by the union's training centre.

Two cooks sift and weigh the salvaged vegetables and whip up a selection of dishes - papaya soup, tomatoes and eggs, stir-fried cauliflower and cabbage.

They are wolfed down by the hungry teenagers, who declared they would never have guessed their meal was made from discarded food.

Their teacher, Alice Lee, hopes the experience will encourage the students to think twice about the food they waste - many of them throw away their school lunches and eat instant noodles from the tuck shop instead, she says.

The project organisers hope it is a meal that will stick in the students' minds and, ultimately, help take a bite out of the city's food waste mountain.