To Lu Zice, discarded oyster shells are not rubbish, but treasures. Oysters are a local specialty and a pillar agricultural industry in Taishan, dubbed "the city of oysters".

The county-level city, administered by Jiangmen in the western part of Guangdong province, generates more than 100,000 metric tons of waste oyster shells annually, threatening the environment.

Lu, founder of Guangdong Bevan Biology Co, said his company has developed oyster shell products that are being used in soil improvement, poultry farming, aquaculture, feed additives, traditional Chinese medicine, filter materials, household chemicals, chemical auxiliaries and related fields, yielding remarkable environmental and economic benefits.

The company has played a leading role in demonstrating resource utilization of oyster shells, forging a path for the treatment of agricultural solid waste along the South China coast.

Lu said that the project is having a significant positive impact on the resource utilization of agricultural solid waste, environmental protection and the sustainable development of marine ranching in Jiangmen.

According to Lu, his company owns five workshops that have been equipped with sorting and cleaning, baking, grinding and tableting facilities.

It can process between 50,000 and 60,000 tons of waste oyster shells annually, producing oyster shell products valued at more than 20 million yuan ($2.9 million). Lu said over the next three years, the company plans to create more than 100,000 tons of oyster shell products — valued at more than 100 million yuan.

Oyster shells are a versatile material with broad application prospects in agriculture, pharmaceuticals, daily chemicals, construction and cosmetics. Lu said his company also has plans to develop tourism, cultural and creative products, handicrafts, souvenirs and other items using waste oyster shells in the following months.

"Thanks to abundant raw material supply and strong government support for agricultural solid waste treatment, the outlook for oyster shell utilization remains highly promising," Lu said.

To achieve his goals, Lu said his company has already established cooperation with the Guangdong Academy of Agricultural Sciences and is having discussions regarding potential collaboration with South China Agricultural University and the Chinese Academy of Agricultural Sciences.

"The key to solving the dilemma of oyster shell solid waste lies in advancing resource utilization toward large-scale production, high-value application and a full industrial chain," Lu added.

Lu, who is also a deputy to the Guangdong Provincial People's Congress, added the industry of processing discarded oyster shells boasts broad market prospects. To this end, his company has planned to expand its scale to be able to annually process from 150,000 to 200,000 tons of waste oyster shells.

"At that level, we will be able to process and utilize most of the oyster shells generated in Jiangmen, effectively eliminating the kind of waste in the future," he said.

"In addition, we will further develop a wider range of applied products, including some high-value-added ones such as calcium used in food additives and other products suitable for daily applications," Lu said.

Chairman of Qi Yong Tang Health Technology (Guangdong)Co, Zhu Ronghua, said the use of oyster shells has a long history, with records found as early as the Tang Dynasty (618-907) in Dunhuang documents.

During the Ming Dynasty (1368-1644), oyster shells were widely used in coastal defense projects. When the Chinese hero Qi Jiguang led the Ming army to fight against Japanese pirates in the 16th century, oyster shell powder was usually mixed with sugar and glutinous rice to create strong building materials for coastal walls, fortifications and shipbuilding, said Zhu. Before the invention of cement, oyster shells served as an important traditional building material.

"Many oyster shell houses still stand in villages along the coast of Guangdong today," he said.

Zhu's company, formerly known as Guangdong Beiyouan New Material Co, has established several oyster shell resource utilization bases in Jiangmen and is expanding into the health industry centered on traditional medicinal uses.

In the residential health sector, relying on its core patented technologies, the company has launched a series of ecological oyster shell powder coatings.

The coatings feature the functions of adsorbing and decomposing formaldehyde, preventing mold and inhibiting bacteria, regulating humidity, and purifying air, and are widely used in places like homes, schools and hospitals.

In March, Lu and Zhu joined hands in their pursuit to convert nondegradable oyster shell waste from aquaculture into high value-added products, such as soil conditioners, green building materials and environmentally friendly adsorption materials.

They have established a complete eco-circular industrial chain and will further expand into the health industry.

Zhu said the two companies aim to continue to further improve the oyster shell collection and transportation system, strengthen technological research and development, expand application scenarios, and promote the large-scale, standardized and branded development of the oyster shell industry in the following months.

Xie Ruiqi contributed to this story.

zhengcaixiong@chinadaily.com.cn