Image copyright VCG/Getty Images Image caption People in Shanghai must divide their rubbish into four types, or risk heavy fines

Things often get heated when the local government brings in a new bin regime, but in Shanghai, strict new regulations have sent the city into a frenzy.

Since Monday, it's been mandatory for individuals and companies in the massive Chinese city to sort and recycle their household rubbish.

People who don't comply not only risk incurring heavy fines, but could potentially have their all-important social credit rating lowered, meaning they may lose out on certain economic or social privileges by not being "model citizens".

The plan is ambitious - Shanghai is the largest and most populous city in the world, with more than 24 million residents - three times the size of London or New York. And according to some reports, only 10% of its waste is recycled. Official statistics show that only 3,300 tonnes of recyclables are collected daily, compared to the 19,300 tonnes of residual waste and 5,000 tonnes of kitchen waste that are collected.

So the tough legislation could set a precedent for other cities as they encourage people to be more environmentally friendly.

How does the new rubbish regime work?

Shanghai is China's most trash-generating city. It produces nine million tonnes a year according to the official Xinhua News Agency.

Waste now has to be divided into four types:

recyclable goods such as bottles and cans

harmful waste like batteries and medicines

kitchen waste, predominantly types of food

other waste, such as bathroom products.

Image copyright Beijing News Image caption Rubbish in Shanghai is divided into four types: hazardous, recyclable, kitchen waste, and residual waste

In the lead-up, the city hired thousands of instructors and conducted tens of thousands of training sessions to help people understand how to divide their rubbish.

But residents are aware that the authorities are strictly monitoring people's behaviour. Local news website Shine says that hundreds of police officers were sent out across the city on Monday, to hand out rectification notices, and fines where necessary.

This has created a sense of panic, and has led to major changes in people's lives. Residents have had no choice but to take extra care to make sure they don't break the rules.

They need to think twice before throwing out containers like bottles, and must empty and clean them beforehand. They also need to wash plastic bags to avoid punishment. Some products also require a degree of dismantlement before being thrown away.

What happens if you break the rules?

The Global Times reports that bin rule flouters can be fined up to 200 yuan ($29; £23), while companies and organisations can face fines of up to 50,000 yuan.

Media playback is unsupported on your device Media caption Five ways to break up with plastic

These are hefty fines for most people.

As most people live in apartments with communal rubbish bins, there is pressure at a community level for people to adhere to the new rules, or risk joint punishment.

The bigger worry for many people is the threat to cut social credit rating - the complicated database which keeps track of every Chinese citizen's financial and social behaviour to determine their trustworthiness.

People with poor social credit can end up excluded from prestigious jobs or private schools. In extreme cases, some can also be banned from travelling on flights, or be blacklisted from public sites.

How do people feel about the new law?

There's been extensive media coverage explaining the changes as they approached and on the Sina Weibo microblog, a lot of people have been saying they're happy about the positive environmental impact.

But many still worry they might get it wrong by mistake,

Tens of thousands were using the hashtag #DividingRubbishSoonSendsShanghaiCitizensCrazy (#快被垃圾分类逼疯的上海居民) - but Sina Weibo has now banned it, seemingly to avoid highlighting the disgruntlement.

Image copyright CCTV Image caption A viral music video helps users decide which bin to put certain unusual products in

Nevertheless social media users have been posting memes and there's even a viral song, set to the tune of an old Chinese song Shanghai Beach but with lyrics explaining correct bin use.

How are companies reacting?

Hotels, which tend to generate large amount of waste, have been struggling as they have also had to ban disposable goods such as toothbrushes and combs, unless visitors specifically requested them.

Restaurants and food delivery businesses have had to ban plastic cutlery according to the Shine news website.

A number of companies are also cleverly capitalising on the bin anxiety. The Global Times noted that one food delivery platform has started offering a new service "which might be called 'takeaway in reverse'," charging a small fee to take individuals' waste, and dispose of it themselves.

Image copyright Sina Weibo Image caption A video went viral showing Shanghai's rubbish law has even led to virtual reality rubbish-dividing games

The China News Service agency says that telecoms giant China Telecom has introduced a system that rewards people for recycling. It shares pictures of branded drop off pods, "which then calculate payments according to market prices and reimburse residents immediately".

Tech companies have benefited, with some creating online games that the Xinhua News Agency suggested were "fun ways to spread rubbish sorting knowhow".

Why was the law introduced?

Image copyright Getty Images Image caption Shanghai is the world's most populous city

China is one of the world's biggest polluters and has been struggling for years with what to do with the rubbish its 1.4 billion citizens generate.

In March 2017, China listed 46 cities to pilot strict rules in waste management, with the hope that by 2020, the nation would be recycling more than 35% of overall waste.

But surveys show that few are able to categorise their rubbish correctly. Caixin says that in December, nearly three-quarters of people in a survey of 3,600 "were unable to correctly identify" how to sort their waste, and warned that the rate of accuracy in waste-sorting would be lower than 27.7%.

So if the massive campaign shows progress in Shanghai, it could spread and make inroads into China's 210 million tonnes of annual waste.

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