HANGZHOU -- Flocks of egrets perch on branches in dense woods in Zhenhai district of East China's port city of Ningbo. The wild bird haven almost disguises what is a pivotal base of bulk liquid chemicals.

Every year after March, these woods of 2,200 square meters bustle with life, as egrets migrate back home to build nests and breed.

Behind the woods is the "iron and steel forest" of the Sinopec Zhenhai Refining & Chemical Company, which is currently the largest refinery in China.

"Egrets need two conditions for breeding -- dense woods suitable for nesting and ample water and food," said Jiao Shengwu from the Research Institute of Subtropical Forestry, under the Chinese Academy of Forestry.

Jiao has conducted five field studies of this area and found that the lush woods and abundant fish and shrimp in the water channels of the refinery and nearby tidal flats in Zhenhai provide a bountiful habitat for egrets, an endangered species under national protection in China.

When building an oil pipeline in 2014, the company extended the pipe to bypass the egrets' nesting area, even though it meant higher costs. In 2020, it relocated the LPG tank further away from the woods.

This bird haven is an important indicator of the refinery's efforts in seeking to build a zero-waste factory. The company's jet fuel tank is only 160 meters away from the woods.

Mo Dingge, Party secretary of the company, said the company has introduced a circular economy model, focusing on resource recycling and zero waste emission.

He said hazardous waste in the petrochemical industry accounts for more than one third of the production, making it difficult for refineries to achieve zero-waste production. According to Mo, the company has made significant strides in its efforts to overcome the difficulties associated with the construction of green factories.

The company has installed 11 cameras in the reserve for live streaming on Chinese social media, which provides audiences with real-time footage of the egrets' lives in the refinery area.

In addition to egrets, there are dozens of other wild bird species such as herons in the area, suggesting sound biodiversity quality, said Jiao.