In a food waste recycling plant in Zhangqiu district in Jinan, East China's Shandong Province, piles of food waste, freshly delivered here from local restaurants and canteens, are waiting to be recycled - by cockroaches.
After being ground, the food is pumped into glass containers in the plant through a pipe, then devoured by millions of cockroaches.
For most people, cockroaches are pests that can leave an offensive odor, transmit viruses on their body surfaces and taint food. But Li Yanrong, a technician-turned entrepreneur from Jinan, has successfully turned them into professional recyclers after spending years studying the notorious insect.
At the recycling plant, which doubles as a cockroach farm, the roaches feed on 15 tons of food waste every day, more than a third of all food waste generated from Zhangqiu's restaurants and canteens. Previously, most of it would have ended up in landfills, causing environmental problems for the areas where they were buried.
Now, the roaches can not only decompose the waste leaving little residue, but also turn it into something useful. After the cockroaches die, their bodies, known to have high protein and nitrogen levels, will be made into cockroach powder to be used as a protein source for animal feed.
Next to the containers is an incubator, a warm and humid environment where young cockroach nymphs are bred. The 54-year-old said the number of cockroaches are growing exponentially, thanks to their resilience and fast-breeding capabilities.
In 2014, there were only 400 kilograms of cockroaches in the plant. In 2015, the number surged to four tons, and this year, it's projected that over 3,000 tons of cockroaches will be produced here.
Cockroaches, commonly seen in southern China, don't usually appear in Li's hometown. Li said he had never seen the insect until 1990, when he was 27 years old. With its dark-brown, flattened body and a pair of wings, the insect frightened him at first when he spotted them in the kitchen, and just like most people, his immediate instinct was to kill the pest.
It wasn't until 2008 that he started studying the insect, after his daughter's research into cockroaches for a school project sparked his interest.
Through his daughter, Li learned that cockroaches, dating back to some 320 million years ago, are one of the most ancient and resilient creatures on earth.
In some places in China, cockroaches are nicknamed "oil thieves" due to their penchant for oil and fermented food. Cockroaches are also a raw material in traditional Chinese medicine, known to be able to promote detoxification.
Li also read that insects, including cockroaches, are a source of nutritious food as they contain high protein levels. Li, who used to work at a recycling company in Jinan, has long believed that everything has its use, and the idea of raising cockroaches soon sprang into his mind.
After doing some research, Li found there were already several roach farms in Shandong that provide raw material for medicine companies. Li visited these farms seeking to gain experience, and was disappointed when he learned how costly it was to run the business. Most of these family-run farms feed cockroaches with grain, and the cost for breeding each ton of cockroaches can hit 10,000 yuan ($1,527). The retail price, however, is sometimes only several dozen yuan for a kilogram.
But he strengthened his idea after An Feng, director of Zhangqiu's environmental sanitation center, told him about the difficulty of dealing with food waste. After landfill, food waste can pollute groundwater and result in health issues for residents. So why not feed cockroaches with food waste?
In October 2011, Li bought a fish tank and started to breed his own cockroaches. After getting his wife's permission, he obtained dozens of cockroach eggs, known as ootheca, placed them in the tank, and started to observe the reproduction habits of the cockroaches in his toilet.
During that time, when Li returned home every evening, he would sit in front of the fish tank and check if any changes had occurred in his mini cockroach farm.
About 20 days later, one hatchling slit its egg open. It was a bright white nymph, resembling a white ant. Other hatchlings started to come out too. Li threw a rice ball into the tank, and the nymphs soon crowded over it and chowed it down.
Within hours after their birth, the nymphs became darker and harder. They then went through a months-long period when they shelled multiple times and eventually grew into adults.
In order to test the cockroaches' eating habits, the couple started to feed the roaches with different kinds of food - spicy, sour, even rotten. It turned out the nymphs had no sense of taste or smell at all. They also have strong immune systems that allow them to digest virtually anything.
As the cockroaches grew larger, the tank started to smell. Li was also afraid that the cockroaches would one day escape the tank, which would have been catastrophic for his family.
He then moved the tank to a house on a hill, made a few wooden boxes, and asked his brother-in-law to further breed and observe the insects. Whenever he had time, he would visit the hill and study their behavior.
Before, Li heard that cockroaches were filthy bugs that defecate on their own food. Through observation, he found that cockroaches never defecated or crawled over what they ate. They usually circled the food and ate from the outside to the inside. They also eat in turn, rather than squeezing against each other.
In order to execute his plan, he had to breed roaches in the thousands, even millions. How to breed them in such large quantities became a problem. Li's solution was to create a three-dimensional farm - the top level would be used for food input, while older, dying roaches fell to the lower level.
Li also tested the cockroach powder and found that chickens fed with the powder were not only healthier but also grew stronger and faster than normal chickens. The eggs of the chicken also have thicker shells.
In his three years of studying the cockroaches, Li applied for over 30 patents, and two have been approved. In 2014, he approached An Feng and asked if the environmental sanitation center could provide him food waste for free. An was happy to do it as it was a better alternative to landfills.
By the end of 2015, Li had resigned from his old job and launched his own company, committing himself fully to the cockroaches - and his recycling plant.