In order to contribute to bringing the current economy closer to the Circular Economy and towards sustainable development, industrial symbiosis is one of the effective methods meeting practical requirements and serving green and sustainable goals. Industrial symbiosis is essentially a cooperative, mutual activity between businesses to optimize the use of inputs and outputs such as raw materials, water, energy, waste and scrap in the process of production and business, resulting win-win for all parties. Industrial symbiosis contributes to make products new value-added, not only effectively using natural resources and human resources, but also saving energy, protecting the environment and balancing the ecosystem.

General concept

What is industrial symbiosis? Industrial symbiosis is one of the methods to bring the current economy closer to the Circular Economy. In other words it is an activity that

Figure 1. Industrial symbiosis process.

helps to use cheap or useless raw materials (such as waste, scraps discarded in the process of industrial production, etc.) that are now recovered for recycling or used as input materials to create new products with added value instead of discarding, occupying land and polluting the environment.

The reuse of industrial waste or by-products as new resource for another production process is of particular interest to many countries around the world. In terms of energy, when reusing industrial waste as raw materials for production to create new products will save more energy than the exploitation of raw materials in nature, because it reduces energy usage in exploiting itself and primary processing ores, limestone, and in operations such as filtering, peeling, grinding and refining, etc.).

In nature, symbiosis is often defined as “any relationship between individuals of different species that are mutually beneficial” such as the food chains of animals, the exchange of different entities bring collective benefits greater than the sum of individual benefits and create an ecological cycle. Similar approaches can also be taken in human industrial activities. Linked with the concept of industrial ecology, industrial symbiosis is also defined as an innovative form to increase productivity, use resources efficiently and is one of the approaches to realize the circular economy towards green growth.

Many countries around the world such as Germany, France, Netherland, Belgium, Japan, China ... have had many initiatives through national action programs and research grants (R&D) to boost the circular economy. In some areas such as energy transition for green growth, waste management, production of building materials and paper, green consumption, etc., there are specific legal regulations and policies for businesses to invest in recirculating economic models.

In recent years, the Vietnamese government has gradually developed and promulgated many mechanisms and policies towards green and sustainable economic development: The National strategy on green growth (Decision No. 1393/QD-TTg dated September 25, 2012); Orientation of Vietnam's National energy development strategy to 2030, with a vision to 2045 (Resolution No. 55-NQ/TW dated February 11, 2020 of the Politburo); National program on economical and efficient use of energy in the period of 2019 - 2030 (Decision No. 280/QD-TTg dated March 13, 2019); National action plan on sustainable production and consumption for the period 2021-2030 (Decision No. 889/QD-TTg dated June 24, 2020); Directive No. 08/CT-TTg dated March 26, 2021 promoting the treatment and use of ash, slag, gypsum of thermal power plants, chemicals, fertilizers and residual gas as raw materials for the production of building materials and in construction, etc.. Especially, the Law on Environmental Protection stipulates that a circular economy is "an economic model in which the design, production, consumption and service activities aim to reduce the exploitation of raw materials, prolong product life, limit generated waste and eliminate negative impacts on the environment”.

Some successful models

Industrial symbiosis in an industrial park is a cooperative activity between enterprises in that industrial park or with enterprises in other industrial parks in order to optimize the use of inputs and outputs such as raw materials. materials, water, energy, waste, scrap ... in the process of production and business. Through cooperation, businesses form a network to exchange factors for production, use common infrastructure and services for production, improve technological processes and improve production and business efficiency.

The benefits of industrial symbiosis include less use of energy, reduction of CO2 emissions, electricity and water consumption and reduction of the amount of waste that should be treated.

Figure 2. Son Hoa Sugar Factory, KCP Vietnam Industry Co., Ltd

The industrial symbiosis thus contributes to cost savings and reduced resource usage by cooperating to maximize the product that can be produced, thereby providing economic and environmental benefits. Firstly, industrial symbiosis helps increase profits and competitiveness, create opportunities for enterprises – both private and public - to develop. Secondly, this will provide significant environmental benefits by reducing the need for materials and waste.

1. In agriculture, forestry

A prominent example in the operation of the circular economy can be mentioned that different by-products in the agricultural and forestry industries such as rice husk, straw, corn stalks, roots ... are input materials for boilers that burn wood pellets from rice husks. Coir shells are also reused as carpet weaving… The price of products created from waste depends a lot on the technology used for recycling that businesses invest in.

In the sugar industry, a typical example is KCP Vietnam Industry Company Limited (KCP) located in Son Hoa district, Phu Yen province. The main business of the KCP Company is the production of sugar and other products from sugar with the current capacity of 10,000 tons of sugarcane/day. The industrial symbiosis chain involves companies with related industries as follows:

- The raw material area (ie. cane cultivation) is 20,000 ha with about 10,000 farmer households earning income from sugarcane cultivation.

- The bagasse-fired plant co-generates steam and electricity with a current capacity of 30MW whose plan is increasing the capacity to 60MW when increasing the output to 6,000 tons of sugarcane/day.

- Producing alcohol, liquor and products related to sugar cane.

- Developing eco-tourism...

Figure 3. Closed cycle in livestock industry

In animal husbandry, in addition to the main benefit of producing food for the market, it also involves many other industries with the same symbiosis such as: processing organic fertilizers, providing energy (generating electricity for heating, fuel...), growing crops for livestock, participating in buying carbon market credits...

2. Thermal power plant

According to the Ministry of Industry and Trade, the amount of ash, slag and gypsum discharged from thermal power plants is more than 16.4 million tons/year. It is expected that in 2021, more coal-fired power plants will be put into operation, generating about 20.5 million tons of ash, slag and gypsum.

Currently in Quang Ninh province, there are 7 thermal power plants operating to produce electricity. According to reports, the amount of fly ash and bottom slag discharged annually by factories is about 7.6 million tons. Currently, all 7 plants have built and approved projects of processing ash and slag consumption from factories in secondary production lines. At the same time, they actively transfer ash and slag to other industries that meet the standards of the Ministry of Construction for reuse as an additive in the production of cement, concrete, roller compacted concrete... This activity has reduced the amount of ash, slag stored at disposal sites in accordance with environmental protection regulations. Specifically, Dong Trieu Thermal Power Joint Stock Company has cooperated with Thanh Tuyen Joint Stock Company to successfully conduct the production of ash and slag from Dong Trieu Thermal Power Plant into the production of unburnt construction materials meeting QCVN 16:2014 standards. The factory’s capacity is 60 million bricks/year, 2 million square meters of roof tile/year and 1 million square meters of terraro tiles/year. Currently, the tiles of the company have been consumed in the domestic market and exported to several countries (1)

Figure 4. Unburnt bricks of Thanh Tuyen Joint Stock Company

using raw materials from ash and slag from Dong Trieu Thermal Power Plant

The reuse of The reuse of ash and slag from power plants to produce building materials makes result that it is much more energy-efficient than the exploitation of natural stones that have to be mined, transported, milled, crushed, etc. The exploitation and processing of natural stones do not only use more energy and labor but also makes natural resources increasingly depleted. The range of electricity consumption of cement factories is from 77.3 kWh/ton to 108 kWh/ton of cement, in which consumption is mainly at the stage of quarrying and clinker production.

3. Solar energy

In recent years, a series of solar power plants have been built. According to the report of the Electricity of Vietnam, by the end of 2020 there are 152 solar projects with a total capacity of 18,678 MWp corresponding to 41- 46 million solar panels. So by 2045 those solar panels will be expired which means a series of solar panels should be discarded. By that time, it will certainly form an industry for solar panel collection, treatment and recycling (2). As is known, the main components that account for a large weight of solar panels are aluminum frames and tempered glass. These two raw materials are valuable resources for recycling into new aluminum or glass products. On the other hand, if the same amount of aluminum and glass must produced from raw materials from ore (boxite or silica…), it would consume a lot of raw materials, energy, labor, machinery and cause environment pollution in the site of mining and processing.

With a few examples above, it shows that the potential for energy efficiency through industrial symbiosis is very large. The industrial symbiosis model has a lot of room for development in eco-industrial parks, thermal power plants, businesses of agriculture, forestry and food processing sectors and many other sub-industries.

Conclusion

The economic transition towards circular economy, green economy, low-carbon economy is an inevitable trend of new era. It is considered by countries around the world as the green industrial revolution of the 21st century. It is also an opportunity for countries to join hands in implementing international commitments in the field of environmental protection and climate change response in order to achieve sustainable development for the health of the people, for the natural environment and the Earth.

In Vietnam, with the current legal basis along with the policy orientation approved by the Government on socio-economic development towards sustainable target, industrial symbiosis is one of the methods to bring the current economy closer to a circular economy. This process requires an involvement of the whole system of all stakeholders including state management agencies, businesses and the people, in which activities of management and reusing, remanufacturing and recycling waste are important factors to promote transition towards the goal of reducing consumption of raw materials and fuel, prolonging life cycle of products, minimizing the amount of waste, bringing Vietnam's economy to catch up with the development trend of advanced countries./.

Eng.  Dang Khac Man

Vietnam Energy Conservation and Energy Efficiency Association

References:

(1) Source: Environment General Directorate of Vietnam - http://vea.gov.vn/detail?$id=1150

(2) http://veecom.vn/a/som-hinh-thanh-nganh-cong-nghiep-xu-ly-va-tai-che-tam-pin-mat-troi-291.html