The Circular Economy – Best Available Techniques

Moving towards a circular economy is a long-term goal of the EU and seen as an essential contribution to the efforts to develop a sustainable, low carbon, resource-efficient and competitive economy.    

The circular economy is viewed as the best option to deal with the decreasing supply of natural resources. It is also an opportunity for economic growth through the innovations required to implement the approach.

The circular economy is crucial in lowering current greenhouse gas emission levels through better waste management and reduced use of resources. In the circular economy, unlike the traditional linear economy, re-sources are kept in use for as long as possible and materials and products are recovered and regenerated at the end of the product’s lifetime.

EU circular economy package

In December 2015, the European Commission presented its latest circular economy package with an action plan and legislative proposals on EU waste policy. The action plan includes several measures regarding legislation, guidance and best practices.

The best practices are provided in the so-called BREF documents (Best Available Technique Reference documents). The BREFs are prepared using experience from the European union industries and are thus a source of reference information. They describe applied techniques as well as present emission and resource consumption levels.

“Implementing a circular approach requires knowledge
of the processes, substances and associated material flows.”

An important new part of the BREFs is the so-called BAT (Best Available Technique) conclusions, which is the final evaluation of the presented available and emerging techniques. The BAT conclusions include descriptions of emissions levels related to the best available techniques and the recommended emission monitoring.

The BREF documents and especially the BAT conclusions are used as a guide for decision makers (e.g. Environmental Authorities) involved in the implementation of the Industrial Emissions Directive. This means, in practice, that when an application for an environmental permit for a new facility is made, the applicant is required to state that the relevant BAT conclusions have been met. For existing facilities, the BAT conclusions will affect the permit conditions within four years of publication.

As the BREF documents play such a big role in guiding best practices and selecting technology, they are also prominent in implementing the circular economy.

In the following section, I review some of the published BAT conclusions and evaluate how the principles of the circular economy are accordingly implemented.

• Common wastewater/waste gas treatment and management systems in the chemical sector (CWW), 06/2016
• Large combustion plants (LCP), 07/2017, covering combustion plants with a total rated thermal input of 50 MW or gasification of coal or other fuels in installations with a total rated thermal input of 20 MW or more
• Waste Treatment (WT), 2018, covering facilities treating, disposing or storing of waste

The Waste Treatment BAT conclusions will enter into force later this year when they have been published in the official EU Journal.

Main principles of circular economy

The Ellen MacArthur Foundation (a well-known British charity aimed at promoting the circular economy) has defined the circular economy based on three principles:

1. Preserve and enhance natural capital by controlling finite stocks and balancing renewable resource flows – for example, replacing fossil fuels with renewable energy or using the maximum sustainable yield method to preserve fish stocks.
2. Optimise resource yields by circulating products, components, and materials at the highest utility at all times in both technical and biological cycles – for example, sharing or looping products and extending product life-times.
3. Foster system effectiveness by revealing and designing out negative externalities, such as water, air, soil, and noise pollution; climate change; toxins; congestion; and negative health effects related to resource use.

On a small scale for an individual industrial company or energy producer, principles 1 and 2 mean more efficient material and energy utilisation. Principle 3 means designing the process so that pollution is minimised, which is controlled by the binding emission levels given in the BAT conclusions. On a larger scale, the principles are achieved through co-operation between companies and industries by circulating materials, side products and waste. 

Waste and wastewater management

The key measures in all the BREF documents for waste and wastewater management are:

1. Implementing an Environmental Management system (EMS) including waste and residue management and a monitoring plan
2. Following the waste hierarchy

1. Waste prevention
2. Preparing/processing waste for reuse/recycling
3. Reuse/recycling of waste
4. Other recovery from waste, e.g. energy recovery
5. Disposal of waste without endangering human health and the environment

One of the key measures in all the BREF documents for waste and wastewater management is following the waste hierarchy.

The CWW, LCP and WT BAT conclusions all contain recommendations and means for minimising water consumption and, thus, wastewater. According to the CWW BAT conclusions, the volume and/or pollutant load of wastewater streams shall be reduced to enhance the reuse of wastewater within the production process and to recover and reuse raw materials.

For minimising fresh water consumption and wastewater generation, several measures are described in the CWW BAT conclusions including process alteration, substituting water cooling with air cooling, recycling wastewater directly or after pre-treatment in processes which are not influenced by the contaminants, and washing at high pressure at a low flow rate.

They do, however, indicate that some water saving measures might under specific circumstances lead to negative environmental impacts and thus need to be carefully considered.

Material efficiency

For material efficiency and recovery, both the CWW and WT BAT conclusions include utilising waste as raw material. The CWW BREF describes purifying slightly contaminated raw material and auxiliaries e.g. with ion exchange or filtration/adsorption and using the purified waste as raw material instead of virgin material.

The WT BAT conclusions indicate that materials should be substituted with waste, in order to use materials efficiently. Waste is used instead of other materials for waste treatment (e.g. waste alkalis or waste acids are used for pH adjustment, fly ashes are used as binders).

The LCP BREF document includes good practices for utilising residues from combustion processes (ashes, slag) in e.g. road construction, surfacing and landscaping work and manufacturing of cement and concrete. It also describes means of optimising the quality of gypsum recovered from flue gas treatment processes in order to make a by-product that can be sold.

Nutrient recycling

In addition to material and water recycling, nutrient recycling is part of component recycling in the circular economy. Nutrient recycling means utilising residues from organic waste treatment (e.g. digestate from anaerobic treatment) as fertiliser and thus returning the nutrients from the organic material back to the soil. The CWW BREF document acknowledges that wastewater sludge from the chemical industry is generally not suitable for agricultural purposes as fertiliser due to the heavy metal content, organochlorines and other persistent sludge components.

The WT BREF document describes the use of digestate from anaerobic treatment of source-separated bio-waste or from industrial and agricultural bio-waste. It indicates that digestate processed from MSW or sew-age sludge with an industrial feed may contain metals preventing its use as a fertiliser. In this case, energy recovery by incineration is recommended.

Sludge treatment and utilisation has been a topic of discussion and debate lately. The BREF documents do not offer a ready answer for the discussion or requirements for fertiliser/sludge quality. National legislations and sludge end users provide these requirements.

Energy efficiency

The LCP and WT BREF documents include BAT conclusions for energy efficiency. The LCP BREF document gives BAT-associated energy efficiency levels (BAT-AEELs) for solid biomass and/or peat boilers for net electrical efficiency and net total fuel utilisation.

No energy efficiency limits are provided in the WT BREF document. There are, however, recommendations for preparing energy efficiency plan and energy balance records.

Conclusions

The circular economy principles are in many ways implemented into BAT conclusions. For many industries water recycling and reducing the need for fresh water has already become common practice. In Finland, we have the luxury of vast water resources and water saving has not always been a top priority. Circulating materials and components and minimising waste are practices that need more attention.

Implementing a circular approach requires knowledge of the processes, substances and associated material flows. For designers, it means re-thinking old familiar processes in terms of water and material recycling and recovery. Increasing internal recycling in processes leads e.g. to higher concentrations of various substances, which may require changes in the required equipment and piping materials.

New raw materials created from waste may have properties that are not fully known in the prevailing process conditions. Doing things in a new way requires a careful risk assessment in order to maintain process safety and operational reliability.

Overall, re-thinking the processes is both an interesting and challenging task for engineers.