Nature has ideal solution to kitchen scraps

Countless larva wriggle among food scraps and other kitchen waste that has been mashed into small pieces and placed in eight big drawers in a room of no more than 20 square meters. Each with a weight of only 0.2 grams even after fully grown, the writhing larva singularly are miniscule. Their capability as a group, however, may easily leave people stunned.

Collectively, eating non-stop, they can digest 100 kilograms of kitchen waste every day. They grow at a tremendous speed－it only takes eight days for a single larva to grow 4,000 times in size.

These particular larva are at home in Xishan Tingyuan, a residential block in Beijing's Haidian district with over 1,900 residents. Since being deployed in the residential block in 2018, these black soldier fly larva have eaten their way through roughly 80 metric tons of kitchen waste.

As authorities in the capital city and many other regions explore onsite disposal of kitchen waste in their efforts to address the mounting trash in the country's urban areas, the humble fly may provide a viable solution.

The larva raising program in the residential block is part of an initiative started by the Vanke Foundation in 2018 to build a more sustainable community, said Lin Hong, a project manager with the organization headquartered in Shenzhen, Guangdong province.

A key task of the initiative is to explore potential solutions to address kitchen waste, which amounts to 50 or even 60 percent of China's domestic waste, she said.

The foundation decided to bring in the fly to Xishan Tingyuan as part of a pilot program for onsite kitchen waste disposal, after a garbage disposal-themed visit from Wang Shi, chairman of the foundation, to Bangalore, India.

Wang, also founder of China's real estate giant Vanke Co, found the approach of disposing kitchen waste with the help of the insect consistent with the foundation's idea of building a sustainable community, Lin said.

Instead of introducing an alien species, the black soldier fly can be found in regions across the country.

With the larva of the fly work around the clock silently, the foundation has introduced a series of activities that aim to proactively involve residents, making full use of the fly's mature larva and its excrement.

Rich in protein, fats and amino acids, the mature larva provides a good choice for fodder. Vanke Service, the property management company for the residential block, has been using the larva to raise fish, which are then awarded to residents who perform well at garbage sorting.

The excrement of the insect can be mixed with garden wastes to create compost. The organic fertilizer generated is then used to nourish the plants in the community.

Xishan Tingyuan resident Tan Lixia has found a lot of fun in activities the foundation has initiated.

The retired teacher has been working as a volunteer to guide other residents in garbage classification for over half a year. "I work as a volunteer once a week for two hours," the 75-year-old said, standing by four trash bins in one of the garbage stations in the community.

For her excellent performance in promoting garbage sorting, she was among the residents awarded fish last year. Tan said the fish fed by the insect tasted good with tender meat.

"The larva raising program makes not only good use of waste materials, but also helps improve our environment," she said, adding she has seen a lot of organic fertilizer used for plants in the community.

According to Vanke Service, a total of 400 cubic meters of garden waste has been used for compost in the past two years. Aside from harvesting 16 tons of organic fertilizer a year, the company has also saved in terms of transport disposal costs.