Proceedings of CUChE Alumni Symposium 2022

On “Circular Economy on Sustainable Basis: The Role of Chemical Engineers”

CUChEAA ISBN: 978-81-954649-1-3

December 2022 P a g e | 64 Volume 2, Issue 1

Circular Economy and Sustainable Development Goals

Ajinkya Kotkar and Suddhasatwa Basu

CSIR-Institute of Minerals & Materials Technology, Bhubaneswar 751013

Abstract

The circular economy (CE) has been touted as the best way forward to achieve sustainability. Realizing the zero-waste

design suggested in the CE approach is the main obstacle in the way of accomplishing this aim. Here, the connection

between CE practices and sustainable development goals (SDG) is briefly examined. The strategies for the valorization of

different types of wastes including urban mining, solid waste (municipal and industrial) utilization, carbon capture and

utilization (CCU), and recycling of plastics are briefly discussed in this article.

Keywords: varorization, circular economy, sustainable, wastes, carbon capture

1. Introduction

Although there is no widely accepted definition for the

circular economy, the European Environment Agency

(European Environment Agency (EEA), 2016) defines it

as follows: “The concept can, in principle, be applied to

all kinds of natural resources, including biotic and

abiotic materials, water, and land. Eco-design, repair,

reuse, refurbishment, remanufacture, product sharing,

waste prevention, and waste recycling are all important

in a circular economy.”

Closing the loops for products and materials is a key

component of the circular economy (CE), which aims to

maximize recycling and recovery. In a CE, materials are

viewed as resources that should be protected and

products as entities whose lives should be prolonged as

much as feasible (Bakshi, 2019). Not only does CE help

to reduce the life cycle emissions of materials and

products by reintegrating them into the process streams

via recycling and recovery, but it also creates

opportunities for new job creation (Schroeder et al.,

2019).

As has been mentioned before, implementing CE

practices can aid in achieving a number of the

Sustainable Development Goals (SDG) targets. 21

targets can be directly attained by CE procedures.

Moreover, they indirectly help to achieve 28 additional

targets (Schroeder et al., 2019). This relationship is

depicted in figure 1. Participation from industries and

policymakers alike can further promote the adoption of

CE practices to enhance industrial synergism which

closes the loop for materials streams within industries.

To apply CE practices linked to solid and e-waste

management, extra work will be needed, such as skill

training and establishing suitable safety conditions

(Schroeder et al., 2019).

Figure 1: SDGs and their relationships in the view of CE practices (Schroeder et al., 2019).

Proceedings of CUChE Alumni Symposium 2022

On “Circular Economy on Sustainable Basis: The Role of Chemical Engineers”

CUChEAA ISBN: 987-81-954649-1-3

December 2022 P a g e | 65 Volume 2, Issue 1

2. Urban Mining for Circular Economy

The technique of extracting and reusing resources from

electronic waste is known as urban mining. Mechanical,

hydrometallurgical, or pyrometallurgical processes are

used to reclaim valuable resources like metals, polymers,

ceramics, etc. Waste electrical equipment, electronic

printed circuit boards (PCBs), and spent batteries are all

sought-after sources of metals due to their higher metal

concentrations than in virgin ore. Figure 2 shows the

global e-waste generation and recycling statistics.

Although the urban mining strategy is essential for

achieving CE, the issues related to waste collection and

treatment prevent its quick adoption. The cost of

recycling and recovering metal values is more than the

income obtained from metal extraction, hence there is

little financial motivation for e-wastes recycling

(Bodsworth, 2018). Furthermore, the collection of e-

wastes is largely done by the informal sector due to the

lack of an integrated infrastructure connecting the formal

channels, waste collectors, dismantlers, and recyclers

(Zheng et al., 2018). This problem is magnified in

developing nations like India, where there is a

substantial informal economy and scant trustworthy

information on e-wastes (Sharma et al., 2021).

As the global electric vehicles (EV) market expands, the

demand for critical battery materials such as Li, Co, and

Ni will continue to increase and is likely to face a deficit

by 2025 in the case of Co and Li (SPG Market

Intelligence, 2021).

Figure 3 shows the supply and demand for Li and Co. In

this scenario, recycling and by extension, urban mining

practices are likely to pick up the pace.

Figure 2: Share of formally and informally processed e-waste on a global scale (Murthy & Ramakrishna, 2022)

Figure 3. Global Supply and Demand for Li and Co (SPG Market Intelligence, 2021)

Proceedings of CUChE Alumni Symposium 2022

On “Circular Economy on Sustainable Basis: The Role of Chemical Engineers”

CUChEAA ISBN: 987-81-954649-1-3

December 2022 P a g e | 66 Volume 2, Issue 1

The problems associated with urban mining can be

mitigated by private-public partnerships, along with

strong participation from policymakers. The informal

sector can be formalized with the help of infrastructure

created for effective recycling aided by the financial

support of the governments (Sharma et al., 2021).

3. Waste Utilization and Valorization

The solid waste stream includes a multitude of

components such as city wastes, industrial wastes, bio-

wastes, e-wastes, and agricultural wastes. The rate of

waste generation has greatly increased as a result of

urbanization and the ever-growing population (Kaza et

al., 2021). Apart from solid wastes, wastewater, and

petroleum sludge, metallurgical slags, and spent catalyst

fines are some key components of the industrial wastes

stream. Depending on the composition and components,

different valorization techniques are used. Furthermore,

the recyclability of the wastes needs to be taken into

account to achieve maximum recycling efficiency

(Kanwal et al., 2021).

The methodologies for waste-to-energy processing of

city wastes or municipal solid wastes (MSW) include

conventional techniques such as incineration, landfilling,

composting, and anaerobic digestion. On the other hand,

the non-conventional techniques include pyrolysis,

gasification, plasma gasification, hydrothermal

carbonization, and torrefaction (Awasthi et al., 2022).

The path forward to achieving CE is the valorization of

the waste stream through various processes to produce

energy and useful by-products. Integrated process design

can be done by employing the waste input-output model

(WIO) and life cycle assessment (LCA) (Tisserant et al.,

2017). In the case of India, the installed waste-to-energy

capacity is 138.3 MW as of 2019 (Charles et al., 2019).

A promising method of processing MSW is biorefinery,

which extends the life cycle of the wastes by turning it

into valuable byproducts and reaching CE. Apart from

solid wastes, plastics can be also converted to liquid

fuels via pyrolysis with up to 80% efficiency (Nizami et

al., 2017). High capital cost for the setup of the

infrastructure for a biorefinery is the major obstacle

along with a consistent supply of high calorific value

feedstock. The establishment of policies that promote

investment in this industry is necessary to address these

issues (Shah et al., 2022).

Bio-waste consisting of cellulose and lignin can be used

as a feedstock for a biorefinery to produce fuels and fine

chemicals by turning it into hub molecules. Figure 4

shows the CE model of bio-wastes. Based on the

geographical location, the distribution and composition

of bio-waste vary greatly. Because of this reason, bio-

waste may not be an acceptable feedstock for producing

bulk chemicals. By building bio-waste processing plants

nearer to the source, it will be easier to incorporate bio-

waste into the chemicals supply chain in the current

scenario (Guo et al., 2019).

Figure 4. Circular economy model of bio-waste (Guo et

al., 2019)

capture and utilization (CCU) has gained traction in

recent years. First-generation petrochemical industries

are one of the most greenhouse gas (GHG) polluting

industries since they produce the majority of CO

. One

strategy for efficient reduction of CO

emissions is to

carry out plastic recycling and CCU simultaneously. The

need for plastics to achieve CE along with other factors,

such as the verticalization of the chemical industry, the

significantly greater market share of oil and gas

companies, and the significantly lower CO

emission

rates associated with the plastics industry compared to

the oil and gas industry, can be used to explain and

justify this scenario.

Table 1: Different refinery processes and associated

products along with waste generated (Varjani et al.,

2021a)

Process

Air Emission

Residual Waste

Generated

Alkylation

CO, SOx, NOx,

hydrocarbons,

particulates

Sulfuric acid or

calcium fluoride,

hydrocarbons

Thermal

cracking

Vents and fugitive

emissions

No residual waste

Polymerization

S from caustic

washing

Spent catalyst

containing

phosphoric acid

Catalytic

cracking

Heater stack gas

(CO, NOx, SOx)

Spent catalysts fines

Isomerization

HCl, vents, and

fugitive

emissions

Calcium chloride

sludge from

neutralized HCl gas

Crude oil

desalting

Hydrocarbons,

particulates, and

fugitive

emissions

Desalter sludge (iron

rust, clay, sand,

water, emulsified

oil)

Vacuum

distillation

Steam ejector

emissions, heater

stack gas

No residual waste

Catalytic

hydrocracking

Heater stack gas

(CO, NOx, SOx)

and particulates

Spent catalyst fines

Proceedings of CUChE Alumni Symposium 2022

On “Circular Economy on Sustainable Basis: The Role of Chemical Engineers”

CUChEAA ISBN: 987-81-954649-1-3

December 2022 P a g e | 67 Volume 2, Issue 1

In the context of CE, the processing of petroleum wastes

is imperative to the pursuit of sustainability. Table 1

shows the wastes generated during typical petroleum

refinery processes. During the refining of crude oil, a

large volume of oily wastewater is generated. This

wastewater, upon further treatment, produces huge

amounts of oily sludge. Oil is extracted from this sludge

via treatment with biosurfactants. Pseudomonas

aeruginosa is a biosurfactant-producing bacteria that is

employed for the oil extraction operation (Suganthi et

al., 2018). Another way to process the sludge is by

advanced oxidation process in which biochar is used as a

catalyst. A promising strategy for process intensification

is the use of a bio-electrochemical technique such as

microbial fuel cells (Varjani et al., 2021b). The spent

catalyst fines are processed through a hydrometallurgical

route to recover metal values, with subsequent use of the

residue in construction materials (Alonso-Fariñas et al.,

2020).

The slag from steel and copper industries poses a

significant environmental concern as these are produced

in large volumes. Copper slag primarily contains silica,

ferrous oxide, ferric oxide, alumina, and metals such as

Pb, Ag, Co, Cu, and Cd in elemental and/or combined

(sulphide/oxide) form. Accumulation of heavy metals

through improper disposal is detrimental to the

ecosystem as they are harmful to living organisms (Phiri

et al., 2021). Hence, its proper disposal is necessary.

After metal recovery by hydrometallurgical,

pyrometallurgical, or combined treatment, the slag can

be used as a construction material. In the case of steel

slag, it can be used in wastewater processing to remove

phosphorus, after which the slag goes through a

significant phase change and the residue can be used as

an additive in the cement industry (Roychand et al.,

2020). Utilization and valorization of these various

components of waste help to increase the life cycle of

material resources and hence, is essential for realizing

the goal of a CE.

4. Conclusion

The shift from a linear economy to a CE is an ambitious

endeavour and will require a substantial effort from

policymakers and industries alike. Industries may aid by

setting up programs that promote recycling and reuse of

products (such as product take-back). While urban

mining is a promising way to employ the 4R (Reduce,

Reuse, Recycle, Recover) strategy, robust infrastructure

along with ample financial support from the government

is needed to circumvent the hurdles associated with it.

The utilization of MSW via waste-to-chemicals and

waste-to-energy strategy is an essential step toward

lowering the amount of waste that ends in landfills. For

the sustainable remediation of petroleum wastes,

copper/steel slags, sludges, and fines, policymakers and

manufacturers must work together to encourage

industrial symbiosis.

References

[1] Alonso-Fariñas, B., Rodríguez-Galán, M., Arenas,

C., Arroyo Torralvo, F., & Leiva, C. (2020).

Sustainable management of spent fluid catalytic

cracking catalyst from a circular economy

approach. Waste Management, 110, 10–19.

https://doi.org/10.1016/j.wasman.2020.04.046

[2] Awasthi, S. K., Sarsaiya, S., Kumar, V.,

Chaturvedi, P., Sindhu, R., Binod, P., Zhang, Z.,

Pandey, A., & Awasthi, M. K. (2022). Processing

of municipal solid waste resources for a circular

economy in China: An overview. Fuel,

317(February), 123478.

https://doi.org/10.1016/j.fuel.2022.123478

[3] Bakshi, B. R. (2019). Sustainable engineering :

principles and practice.

[4] Battery recycling efforts pick up as cobalt, lithium

face potential deficit (2021). News article

[5] https://www.spglobal.com/marketintelligence/en/

news-insights/latest-news-headlines/ battery-

recycling-efforts-pick-up-as-cobalt-lithium-face-

potential-deficit-64847803

[6] Bodsworth, C. (2018). The Extraction and Refining

of Metals.

[7] European Environment Agency (EEA). (2016).

Circular economy in Europe - developing the

knowledge base. In Publication Office of the

Euopean Union (Issue 2).

https://ec.europa.eu/environment/ ecoap/policies-

and-practices-eco-innovation-uptake-and-circular-

economy-transition_en

[8] Guo, Z., Yan, N., & Lapkin, A. A. (2019). Towards

circular economy: integration of bio-waste into

chemical supply chain. Current Opinion in

Chemical Engineering, 26, 148–156.

https://doi.org/10.1016/j.coche.2019.09.010

[9] Kanwal, Q., Li, J., & Zeng, X. (2021). Mapping

Recyclability of Industrial Waste for

Anthropogenic Circularity: A Circular Economy

Approach. ACS Sustainable Chemistry and

Engineering, 9(35), 11927–11936.

https://doi.org/10.1021/acssuschemeng.1c04139

[10] Kaza, S., Shrikanth, S., & Chaudhary, S. (2021).

More Growth, Less Garbage. More Growth, Less

Garbage. https://doi.org/10.1596/35998

[11] Murthy, V., & Ramakrishna, S. (2022). A Review

on Global E-Waste Management: Urban Mining

towards a Sustainable Future and Circular

Economy. Sustainability (Switzerland), 14(2).

https://doi.org/10.3390/su14020647

[12] Nizami, A. S., Rehan, M., Waqas, M., Naqvi, M.,

Ouda, O. K. M., Shahzad, K., Miandad, R., Khan,

M. Z., Syamsiro, M., Ismail, I. M. I., & Pant, D.

(2017). Waste biorefineries: Enabling circular

economies in developing countries. Bioresource

Technology, 241, 1101–1117.

https://doi.org/10.1016/j.biortech.2017.05.097

[13] Phiri, T. C., Singh, P., & Nikoloski, A. N. (2021).

The potential for copper slag waste as a resource

Proceedings of CUChE Alumni Symposium 2022

On “Circular Economy on Sustainable Basis: The Role of Chemical Engineers”

CUChEAA ISBN: 987-81-954649-1-3

December 2022 P a g e | 68 Volume 2, Issue 1

for a circular economy : A review – Part II.

Minerals Engineering, 172(August), 107150.

https://doi.org/10.1016/j.mineng.2021.107150

[14] Roychand, R., Pramanik, B. K., Zhang, G., &

Setunge, S. (2020). Resources , Conservation &

Recycling Recycling steel slag from municipal

wastewater treatment plants into concrete

applications – A step towards circular economy.

Resources, Conservation & Recycling,

152(October 2019), 104533.

https://doi.org/10.1016/j.resconrec.2019.104533

[15] Schroeder, P., Anggraeni, K., & Weber, U. (2019).

The Relevance of Circular Economy Practices to

the Sustainable Development Goals. Journal of

Industrial Ecology, 23(1), 77–95.

https://doi.org/10.1111/jiec.12732

[16] Shah, A. V., Singh, A., Sabyasachi Mohanty, S.,

Kumar Srivastava, V., & Varjani, S. (2022).

Organic solid waste: Biorefinery approach as a

sustainable strategy in circular bioeconomy.

Bioresource Technology, 349(February), 126835.

https://doi.org/10.1016/j.biortech.2022.126835

[17] Sharma, M., Joshi, S., & Govindan, K. (2021).

Issues and solutions of electronic waste urban

mining for circular economy transition: An Indian

context. Journal of Environmental Management,

290(October 2020), 112373.

https://doi.org/10.1016/j.jenvman.2021.112373

[18] Suganthi, S. H., Murshid, S., Sriram, S., & Ramani,

K. (2018). Enhanced biodegradation of

hydrocarbons in petroleum tank bottom oil sludge

and characterization of biocatalysts and

biosurfactants. Journal of Environmental

Management, 220, 87–95.

https://doi.org/https://doi.org/10.1016/j.jenvman.2

018.04.120

[19] Tisserant, A., Pauliuk, S., Merciai, S., Schmidt, J.,

Fry, J., Wood, R., & Tukker, A. (2017). Solid

Waste and the Circular Economy: A Global

Analysis of Waste Treatment and Waste

Footprints. Journal of Industrial Ecology, 21(3),

628–640. https://doi.org/10.1111/jiec.12562

[20] Varjani, S., Mishra, B., Yadavalli, R., Bui, X. T.,

Taherzadeh, M. J., Agrawal, D. C., You, S., &

Chang, J. S. (2021a). Petroleum waste biorefinery:

A way towards circular economy. In Waste

Biorefinery: Value Addition through Resource

Utilization. Elsevier Inc.

https://doi.org/10.1016/B978-0-12-821879-

2.00013-2

[21] Varjani, S., Mishra, B., Yadavalli, R., Bui, X.,

Taherzadeh, M. J., Agrawal, D. C., You, S., &

Chang, J. (2021b). Petroleum waste biorefinery : A

way. In Waste Biorefinery. Elsevier Inc.

https://doi.org/10.1016/B978-0-12-821879-

2/00013-2

[22] Zheng, X., Zhu, Z., Lin, X., Zhang, Y., He, Y.,

Cao, H., & Sun, Z. (2018). A Mini-Review on

Metal Recycling from Spent Lithium Ion Batteries.

Engineering, 4(3), 361–370.

https://doi.org/10.1016/j.eng.2018.05.018