Few shoppers at Swedish fast-fashion chain H&M notice the collection bin next to the cash counter, an inconspicuous receptacle for old and unwanted clothing.

But this is slowly changing.

The retailer, with 12 bins spread across its 10 outlets in Singapore, collected 64 tonnes of unwanted garments last year - about three- fifths the weight of a blue whale. This is almost triple the amount collected in 2015 (22.71 tonnes) and more than five times that collected in 2014 (12.09 tonnes).

This year, H&M Singapore hopes to bag a record 88 tonnes, adding to the more than 40,000 tonnes of unwanted clothing it has amassed globally so far.

Everything collected is sold to the chain's recycling partner, I:Collect (I:CO), for a fee, which is donated to H&M Foundation, a non-profit global organisation .

At I:CO's processing plants in Germany, the United States and India, the clothing is sorted. About 55 per cent of it is resold in second- hand markets worldwide. The remainder is processed - chopped up into fabric shreds which are used as insulation material; or ground into finer fibres and made into cardboard and plastic tarp sheets; or spun with virgin cotton to create recycled yarn.

It is this yarn that H&M uses for its two eco-friendly clothing lines Close the Loop and Conscious, comprising products made of up to 20 per cent recycled materials.

The trend of more people donating their used clothes and more retailers accepting them seems to be growing.

American fashion brand Levi's launched its recycling drive, where shoppers can drop off their unwanted garments and shoes, in 2015 nationwide in the US after a successful pilot programme in 2014.

The North Face, which started collecting unwanted garments and footwear in 2013 in North America, expanded its collection drive to Germany and Canada last year. So far, it has collected 19.3 tonnes of unwanted clothing and footwear in the US alone.

Fashion retail chain Forever 21 started its recycling efforts in San Francisco, California, in 2014.

I:CO works with about 60 retail partners in 65 countries, including Levi's, The North Face and Forever 21. H&M is its biggest partner.

But recycling is more than just about reducing the amount of clothes headed for the dumpster.

Mr Olle Blidholm, H&M's environmental sustainability manager, says that, from a business perspective, it makes sense to take care of social and environmental issues.

"To do good business long term, you need to take into account social and environmental responsibility in a more active way. You have to plan your business in line with what the planet can cope with," he says.

This comes as the global fashion industry cottons on to the environmental impact that the apparel industry has on the planet.

Cotton production is a huge water guzzler. According to non-governmental organisation World Wide Fund, 20,000 litres of water are needed to produce just 1kg of cotton, equivalent to a T-shirt and a pair of jeans.

A report in October, by management consulting firm McKinsey & Company, estimated that if 80 per cent of the population of emerging economies reached the same clothing-consumption level as that of the Western world by 2025, carbon dioxide emissions would increase by 77 per cent to 3,030 million metric tons, up from 1,714 million metric tons in 2015.

This increases the amount of greenhouse gases released into the atmosphere, one of the key drivers of global warming.

Singapore Polytechnic senior retail lecturer Sarah Lim says the time is ripe for fashion retailers to position themselves as environmentally responsible and not just profit- driven.

"Shoppers care more than just about how they look. They want to be part of a larger movement and they care about the social responsibility behind the brands they buy," she says, adding that by collecting old clothes, H&M lets customers participate in the greening process.

She adds: "This also helps the brand establish a green reputation, which helps to build loyalty among the millennials of tomorrow."

According to a 2015 global report by research firm Nielsen, 72 per cent of Generation Z consumers - those aged between 15 and 20 - were willing to pay more for products and services from companies they viewed as committed to making a positive social and environmental impact.

This is up from 55 per cent the year before.

Over at H&M, the Conscious collection, launched in 2012, has been "well-received" here, according to the brand's spokesman, who declined to disclose sales figures. The Close the Loop collection is not available in Singapore.

Mr Fredrik Famm, country manager for H&M South-east Asia, puts the popularity of its eco-lines down to reasonable pricing and the fact that the products are also fashionable.

Customers, he says, are also beginning to be more conscious and perceptive of the brands they consume.

"There's an increase in awareness about sustainability and being socially responsible," he says, adding that the conveniently placed garment-recycling bins at stores make it easy for people to go green.

For shopper Fabian Tan, H&M has given him an easy way to recycle his unwanted clothes.

The market researcher has been donating his unwanted garments to the retail chain since it started its collection drive in 2013.

The 29-year-old says he has donated about 150 items so far.

"A lot of people have the intention to do good and recycle, but when it becomes troublesome to do so, they don't do it in the end.

"Retailers such as H&M make it easy for people to do the right thing."

• The writer's trip was sponsored by H&M.

Orange peel dress, algae cloth

A dress made of discarded orange peels is not orange in colour and does not make the wearer smell like the citrus fruit, it turns out.

After a year-long mentorship programme, a prototype of the dress - made from citrus byproducts recycled into yarn - was created last year. There are plans to take the silky yarn to market.

Fast fashion retail giant H&M supported the project with €150,000 (S$228,700) in grants through its H&M Foundation.

Orange Fiber, the Italian company behind 100 Percent Citrus, was looking for a way to make use of the 700,000 tonnes of citrus waste produced in Italy each year.

The firm was one of five winners at the inaugural Global Change Award in 2015, launched by H&M Foundation to seek out innovative recycling ideas and processes.

Other creative projects that the foundation has funded include the conversion of waste cotton into new textile and use of algae to make cloth.

The foundation, which was set up in 2007, is privately funded by the Stefan Persson family, the Swedish founders and owners of the fashion chain. The family has donated 1.1 billion Swedish kronor (S$177.5 million) to the foundation since 2013.

Apart from supporting fledgling projects, the foundation also works with the United Nations Children's Fund on its global education programme. It also helps, in partnership with international non-profit organisation WaterAid, to supply clean water and sanitation to schools.

On top of that, for every kilogram of old clothing H&M collects in its garment collection drive, its recycling partner, I:CO, donates two euro cents (three Singapore cents) to a local charity.

In Singapore, the beneficiary is The Straits Times School Pocket Money Fund, a community project initiated by the national broadsheet to provide pocket money to children from low-income families for school-related expenses.

Correction note: The story was edited to correct the name of the market researcher Fabian Tan.