On August 2, children learned to use the intelligent garbage sorting and recycling machine in the summer classroom activity of "garbage sorting" in Licang District, Qingdao. Photo by Wang Haibin (People's Vision)

On June 27, in the Steel Ball Community of Erlang Street, Jiulongpo District, Chongqing, two staff members of Chongqing Environmental Sanitation Group were putting the sorted perishable garbage into a special perishable garbage transport vehicle. Photo by Xinhua News Agency reporter Liu Chan

On August 13, Chen Liangen (right), a garbage collector in Xin'an Town, Deqing County, Zhejiang Province, collected agricultural hazardous waste at the breeding base of shrimp farmers in Xinqiao Village of the town. Photo by Yao Haixiang (People's Picture)

What are the uses of leftovers? What process does a plastic bottle have to go through to become a useful material? How to deal with waste electronic products and expired medicines to reduce harm? In the past, our impression of garbage sorting and recycling was a loud shout in the early morning of the community - collect junk! Today, the Internet of Things smart recycling machines, garbage classification applet, anaerobic microbial degradation system, etc., have made garbage classification and recycling become "high-end", and more recyclable garbage has become a renewable resource.

On July 1, the "Shanghai Municipal Domestic Waste Management Regulations" was officially implemented, sparking heated discussions among netizens. On the same day, four topics related to garbage were on the Weibo hot search list. In addition to Shanghai, people have been paying attention to when their cities will begin to implement strict garbage classification policies. According to the requirements of the Ministry of Housing and Urban-Rural Development, by 2020, all cities will fully implement the garbage classification system, and the 46 cities that are the first to try will initially build a garbage classification and treatment system. Some companies have a keen sense of smell. In early July alone, about 200 garbage classification companies were registered.

What is the use of kitchen waste?

Every day before 8 o'clock, Li Ming drove a closed electric tricycle to set off. His destination is the kitchen waste disposal point on Donghua City Street, Dongcheng District, Beijing, which is the green barrel where residents dump leftovers. His job is to sort the kitchen waste and transport it to the collection point, and then hand it over to the staff of the sanitation group for subsequent processing.

In the summer in Beijing, there is a heat even in the morning. After Li Ming opened the green bin, he took a photo to record the original state of the waste, and then put on gloves to sort out the impurities other than the kitchen waste such as the plastic bags that residents had thrown in by mistake. After a while, sweat appeared on his forehead. At this time, he took a measuring rod from the car, stretched it into the bin to detect, and transmitted the data and the photos of the sorted trash cans to the system. He told us: "Kitchen waste is easy to breed mosquitoes in summer, and we also need to clean and deodorize the trash cans."

Li Ming is an employee of Beijing Tianlong Tiantianjie Company. The company has 204 kitchen waste bins throughout Donghua City Street, and each staff member is responsible for about 10 to 15. Company manager Liu Quan said: "The first link in garbage sorting, recycling and reuse is the residents' disposal. If this link is not done well, the subsequent links will be affected. Garbage sorting is the work of "people".

After decades of work, Liu Quan has explored a set of effective methods. "We tell residents about the necessity of garbage sorting by distributing flyers, organizing activities and doing publicity. We invite street staff and party members and cadres to visit the garbage treatment plant. Through field visits, they can see how much garbage is produced in Beijing every day and realize the harm of the piled-up garbage to the environment. Their consciousness has increased all of a sudden, and more and more residents have begun to consciously dispose of it." With the overall stability of the amount of kitchen waste generated, the amount of kitchen waste separated by the community has increased from 60 tons per month at the beginning of 2018 to more than 150 tons per month now, and has entered the recycling and treatment channel.

It is understood that China's domestic waste has the characteristics of "three highs and one low", namely high moisture content, high impurity, high organic matter content and low calorific value. Due to the eating habits of Chinese people, kitchen waste accounts for about 50%-60% of the garbage volume. This type of wet garbage has a high moisture content and low calorific value. It needs to be piled up for 5 to 7 days to discharge 20%-25% of the total amount of garbage. The calorific value can reach the most suitable combustion conditions.

In view of the characteristics of Chinese kitchen waste, some companies are constantly exploring. The Guangzhou East Biomass Comprehensive Treatment Plant project invested, built and operated by Langkun Environmental Group is one of the representatives.

The person in charge of the factory said: "We mainly deal with catering waste, kitchen waste, etc., using the process of pretreatment + combined anaerobic digestion + comprehensive utilization. At present, the contracted treatment scale for the six central districts of Guangzhou is 400 tons of catering waste, 600 tons of kitchen waste, and 2,040 tons of other types of biomass waste. It is currently the world's largest urban organic waste treatment project."

How to solve the problem of kitchen waste with many impurities and complex composition? The person in charge of the factory said: "After the kitchen waste is transported to us, it must first be cleaned, which is the most difficult part of the kitchen waste treatment process. The method we adopt is high-pressure pressing and sorting. The purpose is to achieve the dry and wet separation of kitchen waste, and obtain wet components (organic matter) and dry components (impurities)."

The factory uses an automatic ultra-high pressure garbage pressing device, and the garbage after separation can be turned into "treasures". Among them, the wet component is used for anaerobic fermentation, and the biogas produced in the anaerobic fermentation process can be converted into electricity; the sludge of anaerobic fermentation can be processed into raw materials for biofertilizer after dehydration. The dry component is used for incineration and power generation.

How can a beverage bottle be reborn?

Data released by the United Nations Environment Program show that the global production of beverage bottles consumes nearly 17 million barrels of crude oil each year, 13 million tons of plastic waste flows into the ocean each year, and about 15 million marine organisms die due to plastic waste. One million beverage bottles are sold every minute in the world, and it takes 450 years for plastic to decompose in the natural environment.

Are the plastic bottles we discard really not being used? What kind of life journey will a plastic bottle go through after leaving the consumer? Recently, we visited Yingchuang Recycling Resources Co., Ltd. in Shunyi District, Beijing, and felt the process of beverage bottles from being discarded to being reborn.

Put an empty plastic bottle into Yingchuang's H-31 beverage bottle intelligent recycling machine, and the bottle turned a few circles in the recycling machine and fell into the recycling bin. However, if the bottle put into the recycling machine is an unfinished bottle, it will not fall into the recycling bin. It turns out that this recycling machine can sense the weight of the bottle. Compressing the recycled empty bottles can reduce the cleaning costs of workers and improve recycling efficiency.

After the recycling is completed, users can choose to donate or receive coupons and get rebates. There is no need to download mobile applications for choosing coupons. The whole process from returning the bottle to exchanging points can be completed through the WeChat applet.

Consumer participation ends here. However, for the plastic bottles in the recycling machine, this is only the first step in its recycling journey.

Plastic bottles entering the recycling machine will be compressed, waiting for more bottles to fill the recycling bin. Yingchuang staff told us that whether the recycling machine is operating normally and whether the recycling bin has been filled can be transmitted back to the background in real time. The background can arrange the best processing route for nearby cleaning personnel according to the situation of each recycling machine.

After that, these plastic bottles will be transported to the sorting station for sorting and packaging, and pressed into bottle bricks to enter the Yingchuang recycling factory.

The bottle body can be recycled, but how to recycle the bottle caps and labels on the bottle? Can the labels and bottle caps be made into bottles after recycling?

It turns out that a beverage bottle can be divided into 3 parts. Among them, the bottle body part can achieve a "bottle to bottle" level conversion. After recycling and regeneration, it is still food grade and can be used to hold beverages. But bottle caps and labels cannot. After Yingchuang automatically sorts the recovered bottles, the bottle caps and labels are removed and processed in other ways. Finally, the PET (polyethylene terephthalate plastic) beverage bottles are mainly entered into the recycling factory.

The staff of Yingchuang also showed us several crystal particles, which were all broken and cleaned beverage bottle fragments. These crystal plastic fragments have been restored to cleanliness and are waiting to be processed into recycled polyester chips, or directly to a new life.

Now, China's annual consumption of plastic bottles exceeds 5 million tons, about 200 billion, ranking first in the world. Yingchuang processes 50,000 tons of waste PET beverage bottles every year, which is equivalent to saving 300,000 tons of oil.

The story of a bottle will continue.

Can hazardous waste become harmless?

Kitchen waste can be converted into biogas and incinerated to generate electricity, and plastic bottles can be crushed and reused. How to deal with expired medicines in people's home medicine cabinets and waste batteries replaced by remote controls?

In June 2016, the new version of the "National List of Hazardous Wastes" was released, and expired household medicines were listed. Once the medicine expires, it will not only lose its therapeutic effect, but may also cause harm to the human body. If expired drugs are discarded and incinerated with ordinary household garbage, it will seriously harm the environment and cause excessive levels of antibiotics and other drug ingredients in the soil and water sources.

Expired drugs are very harmful, but China's handling of expired drugs seems insufficient. The "White Paper on the Recycling of Expired Drugs in Chinese Households" shows that about 78.6% of Chinese households have "small medicine boxes", of which more than 80% of households do not have the habit of regular cleaning, and few people know how to properly handle expired drugs at home.

Even though there are many difficulties in recycling expired drugs, those who are interested have not given up. Since 2004, Guangzhou Pharmaceutical Group Co., Ltd. has held expired drug recycling activities from March 13 to August 31 every year. At present, Guangzhou Pharmaceutical has recycled more than 1,500 tons of expired drugs.

The recycled expired drugs will be sealed and packaged, labeled, with the recycling point, person in charge, recycling unit and recycling date indicated, and transported to the abandoned waste treatment plant by a special dangerous goods transportation vehicle, handled by professionals, and put into the pyrolysis gasification incinerator for harmless treatment.

It has basically become a consensus that waste batteries, waste electronic products, etc. are hazardous waste. Electronic waste accounts for only 2% of the garbage in the world's landfills, but it accounts for 70% of all hazardous waste, which seriously harms the environment. But at the same time, waste electronic products may be turned into treasure. The International Telecommunication Union estimates that the value of gold thrown into the waste dump in 2016 was US$21.5 billion, and the value of copper was US$13.9 billion.

The "Program for the Implementation of the Extended Producer Responsibility System" issued by the General Office of the State Council points out that producers should be responsible for the resource and environmental responsibilities of their products throughout the life cycle. In other words, for electronic product manufacturers, it is necessary not only to manage the production links, but also to grasp the battery recycling links.

Now, the power batteries eliminated from new energy vehicles can be applied to other fields through cascade utilization to give full play to their use value. Batteries whose performance has dropped to less than 30% of the original need to be disassembled and recycled, and the precious metals in them are extracted chemically.

The action of garbage classification has gradually become a trend, and the garbage classification industry is gradually forming a complete industrial chain.

Zhang Yi, chairman of the China Strategic Emerging Industries Environmental Protection Alliance, said: "Although developed countries started garbage sorting earlier than us, no country has taken garbage sorting to such a high level as China." According to Zhang Yi's estimate, in the next 10 years, the scale of the industry driven by garbage sorting will be about 400 billion yuan.

China's garbage sorting industry is gradually maturing. The life journey of garbage shows us that the garbage sorting industry is not only a public welfare cause to protect green mountains and clear waters, but also brings a blue ocean of business, allowing us to see the gold and silver mountains in garbage. (Zhang Pengyu Cao Yingyue)

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