From food to fertilizer
Beijing grapples with 2,600 tons of kitchen waste daily
Two large machines are buzzing and emitting a slight odor of fermentation inside the kitchen waste disposal room. The 40- squaremeter room is in the corner of a residential district in Beijing’s Xicheng district.
Food scraps from more than 2,100 households and a canteen are “swallowed” by these two machines and undergo processing.
Sun Chunming, of the property service center, says each machine can dispose of 500 kilograms of kitchen waste a day. The machine grinds the food scraps and through a proprietary microbial process, 70 percent of the waste is converted into water, carbon dioxide and organic solids that can be further refined into fertilizer.
“Together the two machines can produce around 1,000 kilograms of fertilizer a day and the fertilizer
is applied to nearby green spaces,” Sun says.
The on- site process is used in more than 30 canteens in China’s central government agencies, municipal commissions, and some schools in Beijing. Lin Jinwen, an official from the Beijing Municipal Commission of Urban Management, says 128 canteens in government agencies are receiving subsidies to install this disposal equipment. However, it is hard to spread the on- site kitchen waste treatment to restaurants and catering businesses as they are unwilling to pay for this equipment.
China’s challenge
Liu Jianguo, a professor at Tsinghua University’s School of Environment, says the disposal of kitchen waste is a challenge with Chinese characteristics. The nature of food scraps is different from that in other countries as they contain more oil and salt. They cannot easily be incinerated like other garbage and will pollute underground water if they are sent directly to landfills. “In Japan and some other countries, restaurants have to bear the cost of food waste disposal. However in China, restaurants do not have to pay,” Liu says. China’s growing food consumption has brought a rapid growth in food waste. In Beijing and other big cities that boast thriving catering businesses, the problem is particularly serious. According to the Beijing Municipal Commission of City Management, about 2,600 tons of kitchen waste is produced by more than 40,000 restaurants and dining halls of institutions and schools every day and this is expected to reach 2,900 tons in 2020. However, the city’s 10 food waste treatment centers, together with on- site treatment equipment, can handle only 2,000 tons per day.
Filling the ‘ gap’
Beijing is building five new processing centers in Haidian, Fengtai and Shunyi districts. They are expected to be in use at the end of the year, raising Beijing’s processing capacity to 2,800 tons per day.
Nangong in Daxing district is one of Beijing’s biggest kitchen waste disposal centers, with a daily capacity of 400 tons. Every day, speciallydesigned trucks go to designated restaurants and canteens to collect food waste and take it to the center.
The waste first goes into a solid- liquid separator. The solid material enters the composting system, and the liquid enters the treatment plant.
Zhang Yang, manager of the Nangong center, says composting is a mature method of disposal, and has to some extent guaranteed the harmless treatment and reuse of kitchen waste.
But he adds that the fertilizer derived from kitchen waste has limited sales channels and low market recognition. The output return is much lower than the processing cost, so food waste disposal still needs government subsidies.
The kitchen waste collected from restaurants is not purely food scraps. It is mixed with disposable chopsticks, rags and even glass bottles and other debris, which is a headache for Zhang.
“The non- kitchen waste sometimes damages our disposal equipment,” Zhang says. “We are responsible for handling kitchen waste, but we have no right to supervise the garbage classification of restaurants. We hope the authorities can take coercive measures regarding this.”
Garbage storing
In March, the State Council issued a plan requiring 46 cities to carry out mandatory garbage sorting by the end of 2020. Under the plan, all public institutions and companies are required to separate hazardous waste, kitchen waste and recyclable materials.
Beijing’s Tongzhou district, the capital city’s sub- center, will implement mandatory garbage sorting in public institutions and more than 500 restaurants by the end of this year.
Every day at 9 am, staff at Tongzhou Zhenchongqing Restaurant put the special green kitchen waste bin full of food leftovers out for the sanitation companies to collect.
“A napkin, a chopstick – even a toothpick – cannot be mixed into the kitchen waste,” restaurant lobby manager Wang Liang says. “If the recyclers find other garbage included, they ask us to take it out.”
Liu Jianguo says the implementation of garbage sorting will be challenging, requiring legal support and improved regulations. He hopes to see more detailed official policies and regulations on kitchen waste disposal in the city.