Aug. 15, 2022

Investigation of current food waste disposal in Lanzhou

January 18, 2011

Source: Gansu Daily,

Reported by: Qi Xingfu

Food waste refers to refuse, such as grease, slop, and other leftovers, that are byproducts generated by food processing enterprises. If properly processed, food waste can be reused, often retaining a sizable portion of its original value. If not properly processed however, food waste can become a threat to both the environment and food security.

In Lanzhou alone, more than 6,000 catering units produce over 100 thousand tons of food waste each year. Where do all of these waste products go? How are they disposed of? A one-month investigation reveals the answers.

The Mysterious Reclamation in the Night

Winter evenings come early in Lanzhou. Around 7:00 p.m., the whole city becomes brilliantly illuminated by neon lights. Dazhongxiang Lane, a street famous for its catering industry, is about to experience its busiest time of day. In freezing cold temperatures, the aroma of various dishes permeates the street.

At about 7:40 p.m. a three-wheeled farm truck arrives from the north entrance of the street and stops near a restaurant in the middle of the street, causing quite a racket.

The truck bed contains three plastic barrels, one of which is filled with leftover food waste. Wearing a heavy-duty apron, for protection against the waste products, the driver enters the restaurant through the side door, which leads directly to the kitchen. After a short time, he emerges with another barrel full of leftovers.

“Sir, what are these leftovers for?” the journalist asks the driver. “Feeding the pigs,” the man answers, as he rushes back to the truck and drives away toward Yongchang Road. The journalist immediately follows the truck.

On the Yongchang Road the man enters two more restaurants and returns with more leftovers. He then drives away along the Nanbinghe Road to Xiguanshizi.

The man collects leftovers at the Xiguan Comprehensive Market, restaurants at the southern end of the Yongchang Road, and along Gannan Road. He seems very familiar with the kitchens and staff at all of the restaurants and hotels. He casually goes straight to each kitchen and retrieves the food waste without any direction from the staff.

By about 9:30 p.m., the three plastic barrels on the man’s truck have been filled with leftovers. He drives the truck northward along the Jingning Road to the Nanbinghe Road, and continues eastward, passing by the Children’s Park, Dajiaoliang, Yantanqiaotou, and the Tianshuibeilu Road. The journalist continues to follow him. After finally arriving at the east side of Yantan Township, the truck disappears into a dark tunnel without any streetlights.

Where do the 100 thousand tons of food wastes go?

In subsequent investigations, the “mysterious” man driving the three-wheeled truck was seen collecting food waste on Nongminxiang Lane and Caochangjie Street, at the Railway Bureau, and in many other places. This is a common occurrence according to many Lanzhou citizens and there is more than one “mysterious” man.

At present, there are more than 6000 food-serving establishments in Lanzhou. If each unit produces 20 kilograms of food waste each day, 100 thousand tons of food waste will be produced each year. According to Says Su Yun, a professor at the Lanzhou University School of Management, “Properly processed food waste can be safely reused, but if not processed properly it will become a threat to both the environment and food security.” Many experts and scholars are very concerned about improper disposal of food waste. Food waste spoils easily and can cause contamination of soils and groundwater. Additionally toxic substances are regularly found in the organs, fat, and muscles of livestock that are fed food waste. Human consumption of meat from these livestock can lead to the degeneration of the immune system as well as liver and kidney failure. Furthermore, “recycled oil”, made from reprocessing used kitchen oil via a heating, filtration, and distillation process, is often resold as new oil. This “recycled oil” is not safe for human consumption yet still makes its way back to the dinner table of unaware consumers.

According to the original investigation, only 20 percent of all the food waste in Lanzhou is disposed of safely each year. The treatment and disposal of the remaining food waste is unclear.

With the help of an anonymous insider the journalist conducted several secret investigations in some very out-of-the-way places in Lanzhou. Many of the pig raisers’ barns are located in isolated areas, far from neighbors or towns. Fences and locked gates along with vicious guard dogs are used to keep out unwanted eyes. Despite the impediments, the investigations were able to verify that pigs in Yangchangbao, Yanjiaping, Xiaopingshan, as well as pigs in several other places, are fed with leftovers from restaurants throughout the year.

According to the insider, “only certain types of food waste can safely be used as pig feed.” In order to convert general food waste into pig feed the oils must be separated from the food waste. The separated oil is commonly referred to as recycled oil. The pig raisers often sell this recycled oil to dealers who specialize in the distribution of this product.

During the investigations reporters discovered that food waste is also obtained directly from the sewers and underground wells. Is this food waste used to feed pigs as well? The insider revealed that, “not many food leftovers find their way into the sewers. The people who collect food waste in this manner mainly process it into recycled oil.

People are concerned about the uses of recycled oil

According to the insider, a pig raiser can get at least five to eight tons of recycled oil from refinement of food waste.Illegal processors that specialize in this business can produce many of tons of recycled oil each year.

What is the recycled oil used for? Reporters found that recycled oil can generate a significant profit. During 2010, the purchase price per ton of recycled oil was over 3000 Yuan. The insider told the reporter that the recycled oil processors in Lanzhou have an exclusive sales chain, and no one can say for sure exactly where the recycled oil ends up. However, it is speculated that the recycled oil is often mixed with cooking oil. After the filtration and deodorization processes, it is nearly impossible to distinguish between the recycled oil and the cooking oil. It is horrifying to think that recycled waste oil might be returned to the dinner table. According to Zhou Jun, Chief of Yongdeng Huanke Cellulous Material Experimental Factory, at least 10,000 tons of oil are produced in Lanzhou each year. He is deeply concerned with the illicit usage of recycled oil.

In early 2010, a comment from He Dongping, a Professor at the Food Science and Engineering School at Wuhan Industrial College, caused country-wide uproar. He claimed that Aflatoxin, a harmful substance with a toxicity 100 times higher than arsenic and known to cause cancer, is one of the main components of recycled oil. He also claimed that about two to three million tons of recycled oil is returned to dinner tables in China each year.  

Is recycled oil used at dinner tables in Lanzhou?

According to some surveys, recycled oil is mainly used for cooking in some small restaurants located on the city fringe, near the countryside. In addition some street vendors use recycled oil in their carts.

During the investigation reporters discovered that dealers are often seen bringing recycled oil, in dirty plastic barrels, to food service establishments along the urban/rural fringe. “What kind of oil is this? Where is it from?”  Some of the restaurant owners said it was grapeseed oil while others said it was salad oil.  Few owners agreed to comment further on the source of the oil.

According to an inside source, the selling price of the unidentified oil is four Yuan per barrel. Ordinary grapeseed oil sells for six Yuan in the oil market.

It was also discovered that since 2004, a large amount of oil has been hunted down and seized by authorities in Lanzhou. In the summer of 2010, authorities in Lanzhou formed an alliance and initiated random checks for illicit usage of recycled oil. During the investigation, authorities claimed that there was no indication that any recycled oil had found its way back to the dinner table.

Translator: Yang Wenlong, Ding Jieqiong
Proofreader: Annie Geratowski, Karen Marshall

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