Recycling and Circular Economy Standard — WIA-ENE-023
The third tier of the waste hierarchy introduced in Chapter 1, namely RECYCLING, is subdivided in this standard into six branches of technology[1]. First, MECHANICAL_RECYCLING is the most common branch and uses purely physical operations of shredding, washing, separation, and re-pelletisation. Second, CHEMICAL_RECYCLING uses chemical processes such as depolymerisation, pyrolysis, and gasification to reduce polymer chains to monomers or synthesis gas. Third, THERMAL_RECYCLING uses heat to recover materials, but where the only output is energy the operation is downgraded to RECOVERY in the hierarchy. Fourth, BIOLOGICAL_RECYCLING covers microbially mediated decomposition pathways such as anaerobic digestion and INDUSTRIAL_COMPOSTING. Fifth and sixth are socio-technical variants in which output of higher economic value than input is classified as UPCYCLING, and output of lower economic value as DOWNCYCLING.
Each branch is assessed along five quantitative axes: yield ratio, residue ratio, energy consumption (MJ per kilogram of input), output grade, and CO2 saved (kg per kilogram of input). This chapter presents the assessment methodology in accordance with ISO 14021:2016, ISO 14025:2006, ISO 14040:2006, and ISO 14044:2006, and explains how each metric is serialised in the WIA-ENE-023 envelope.
| Technology ENUM | Yield | Residue | Energy (MJ/kg) | CO2 saved (kg/kg) |
|---|---|---|---|---|
| MECHANICAL_RECYCLING (PET_BOTTLE) | 78-88% | 12-22% | 2.1-3.5 | 1.8-2.3 |
| MECHANICAL_RECYCLING (HDPE) | 72-84% | 16-28% | 2.5-4.0 | 1.5-2.0 |
| CHEMICAL_RECYCLING (depolymerisation) | 85-95% | 5-15% | 15-28 | 0.8-1.4 |
| THERMAL_RECYCLING (pyrolysis) | 60-75% | 25-40% | 22-38 | 0.4-0.9 |
| BIOLOGICAL_RECYCLING (INDUSTRIAL_COMPOSTING) | 40-55% | 45-60% | 0.8-1.5 | 0.6-1.1 |
| UPCYCLING (design-led conversion) | 65-90% | 10-35% | 1.2-4.0 | 0.5-1.8 |
MECHANICAL_RECYCLING accounts for approximately 85 percent of plastic material recovery worldwide[2]. The process generally consists of five sequential stages. First, incoming inspection and primary separation: near-infrared (NIR) optical sorters identify the seven principal polymer classes PET, HDPE, PVC, LDPE, PP, PS, and OTHER with approximately 95-98 percent accuracy, while air classifiers remove paper, metals, and inert contamination through density differences. Second, shredding: particle size is homogenised to approximately 8-12 mm to standardise the throughput of downstream operations. Third, washing: caustic soda solution removes label adhesive, printed inks, and organic contamination, and food-contact grade R_PET production additionally requires a vacuum devolatilisation step. Fourth, drying and density separation: float-sink tanks separate polyolefins with specific gravity below 1.0 (PE and PP) from PET and PVC with specific gravity above 1.3. Fifth, melt extrusion and pelletisation: single-screw or twin-screw extruders melt the material at approximately 230-280 degrees Celsius and produce reclaim pellets.
The structural limit of MECHANICAL_RECYCLING is degradation of molecular weight per processing cycle. For PET, intrinsic viscosity (IV) drops by approximately 0.05 dL/g per cycle, and after five cycles the material can no longer meet the food-contact threshold of IV greater than or equal to 0.78 dL/g. This five-cycle ceiling is the structural argument for division of labour with CHEMICAL_RECYCLING and explains why a circular economy for PET cannot rely on MECHANICAL_RECYCLING alone.
PET bottle collection systems vary substantially across jurisdictions. Deposit-refund systems (DRS) deployed in Germany, Norway, and the Republic of Korea (the latter as a 2025 pilot programme) consistently achieve collection rates above 90 percent, compared with 60-75 percent for kerbside separate-collection systems. The simulator allows operators to model DRS deposit values from 0.10 to 0.25 euros and observe the collection-rate uplift relative to kerbside baselines. In the Korean pilot, the deposit value is set at 100 won (approximately 0.07 euros) and projected collection rate is approximately 82 percent by 2028.
CHEMICAL_RECYCLING reduces polymer chains to monomers, oligomers, or synthesis gas, breaking the five-cycle ceiling of MECHANICAL_RECYCLING. This standard subdivides CHEMICAL_RECYCLING into four sub-technologies. First, depolymerisation: glycolysis, methanolysis, or hydrolysis of PET recovers monomers (BHET, DMT, TPA) at yields of 85-95 percent. Second, pyrolysis: polyolefins (PE, PP) are thermally cracked at approximately 400-600 degrees Celsius under anaerobic conditions to produce pyrolysis oil. Third, gasification: mixed plastic waste is partially oxidised at approximately 800-1200 degrees Celsius to produce synthesis gas (CO + H2). Fourth, dissolution: selective solvents extract a target polymer from mixed streams.
The environmental impact of CHEMICAL_RECYCLING is contested. Yield is higher than for MECHANICAL_RECYCLING, but energy consumption is approximately 7-10 times greater, and the CO2 saved depends strongly on the input contamination, output grade, and the carbon intensity of the energy supply. The 2023 report of the EU Circular Plastics Alliance concludes that CHEMICAL_RECYCLING produces a net positive CO2 saving only for food-contact grade R_PET production, and may produce a net negative saving for general industrial streams. The downgrade justification field in WIA-ENE-023 envelopes is designed to capture this case-by-case variability explicitly.
THERMAL_RECYCLING is the family of heat-mediated recovery technologies, but only operations that produce material outputs (for example, pyrolysis oil) are classified as RECYCLING in the hierarchy. Operations that produce only energy outputs (electricity, heat, solid recovered fuel) are downgraded to RECOVERY. The WIA-ENE-023 envelope automatically classifies the tier through the output_material metadata field: outputs labelled pyrolysis_oil or synthesis_gas are routed to RECYCLING tier, while electricity, heat, or srf are routed to RECOVERY tier.
BIOLOGICAL_RECYCLING covers food waste, garden waste, paper, and EN 13432-compliant BIODEGRADABLE plastics that are microbially decomposed into compost, biogas, or digestate. The two principal technologies are anaerobic digestion (AD) and INDUSTRIAL_COMPOSTING. AD recovers methane gas as the principal output and may be classified as RECYCLING (the methane is treated as chemical feedstock) or RECOVERY (the methane is used as fuel) depending on the operator's declared output use. The simulator allows operators to model both classifications and observe the resulting differences in EPR fee allocation and hierarchy-tier accounting.
UPCYCLING covers cases where the output economic value exceeds the input value; DOWNCYCLING covers the reverse. Quantitatively, the ratio R is defined as output unit price divided by input unit price, with R greater than 1 classified as UPCYCLING and R less than 1 as DOWNCYCLING. Recycling PET bottles into apparel fibre (R approximately 1.5) is UPCYCLING; recycling PET bottles into agricultural binding twine (R approximately 0.6) is DOWNCYCLING.
The following is a sample WIA-ENE-023 envelope for a PET bottle recovery flow.
{
"envelope_id": "8e7f3c2a-...",
"host_id": "korea-pet-host.kora.or.kr",
"tenant_id": "kora-2024-q4",
"envelope_class": "RECYCLING_FLOW",
"tier": "RECYCLING",
"technology": "MECHANICAL_RECYCLING",
"material": "PET_BOTTLE",
"output_material": "R_PET",
"jurisdiction": "KR",
"directive_ref": "KOREA_EPR",
"input_mass_kg": 12450.0,
"output_mass_kg": 10583.0,
"yield_ratio": 0.85,
"residue_kg": 1867.0,
"energy_mj_per_kg": 2.8,
"co2_saved_kg_per_kg": 2.1,
"timestamp": "2024-12-20T08:31:42Z",
"traceparent": "00-..."
}[99] All code samples and the reference simulator for this chapter are reproducible from the GitHub repository cited above.
The yield ratio is defined as output material mass divided by input waste mass, calculated per EN 13430:2004 section 6. The residue ratio is residue material mass divided by input waste mass, with yield plus residue equalling 1.0. The point of measurement is the final pellet or monomer output, not the entry to the processing step; intermediate volatile losses and moisture evaporation are excluded from the yield calculation. For food-contact grade R_PET production, only output meeting the food-contact grade is counted in the yield numerator, and any output downgraded to industrial grade is classified separately as DOWNCYCLING output.
The WIA-ENE-023 envelope serialises yield_ratio and residue_ratio in separate fields and rejects any envelope where their sum falls outside the 1.0 plus-or-minus 0.01 tolerance band. Output grade (food-contact, industrial, downcycling, energy-recovery) is serialised in the output_grade field, and for R_PET flows the grade declaration must additionally carry one of three certification codes: FDA_FOOD_CONTACT, EU_REGULATION_10_2011_COMPLIANT, or MFDS_FOOD_CONTACT_KR.
Energy consumption per kilogram of input is calculated per the Life Cycle Inventory (LCI) procedure of ISO 14040:2006. The default system boundary covers from waste arrival at the recovery facility to the final output stage; transport to the facility may be included or excluded at the operator's discretion. The envelope serialises the system boundary in the system_boundary field to ensure comparability across hosts.
CO2 saved (kg per kilogram of output) is calculated as the CO2 footprint of virgin material production (from extraction through primary processing) minus the CO2 footprint of the recovery process. For PET, virgin production emits approximately 2.3 kg CO2 per kg, MECHANICAL_RECYCLING emits approximately 0.4 kg per kg, yielding a CO2 saving of approximately 1.9 kg per kg. The calculation follows ISO 14067:2018 "Carbon footprint of products" and gives precedence to the emission factors in the regional Life Cycle Inventory database.
Recovery flows are classified as closed-loop (output re-enters the same product category as input, for example PET bottle to new PET bottle) or open-loop (output enters a different category, for example PET bottle to apparel fibre). ISO 14044:2006 section 4.3 distinguishes the LCA calculation methodology for the two cases, and the WIA-ENE-023 envelope serialises this distinction in the loop_type field with values CLOSED or OPEN. Closed-loop recovery has the advantage of indefinite recyclability but incurs higher per-unit cost (approximately 20-35 percent more) due to food-contact certification, labelling, and washing requirements. Open-loop recovery has lower per-unit cost and broader output markets but shorter material lifetimes.
Optical sorting is the keystone technology of the separation stage. NIR spectroscopy identifies the seven principal polymer classes with approximately 95-98 percent accuracy. Black plastics weakly absorb NIR and have historically been difficult to identify, but AI-based combined RGB-and-shape recognition models introduced after 2024 have raised black-plastic identification accuracy to approximately 87 percent. The simulator allows operators to input the polymer composition of an incoming stream across the eight categories (the seven principal plus black plastics) and observe the resulting yield and residue under both NIR-only and AI-augmented sorting configurations.
Recovery facility operation is managed across three quality axes: input quality, process stability, and output grade. Input quality is measured by contamination percentage and is binned at five thresholds (5, 15, 30, 45, 60 percent), each driving a different downstream pathway. Streams below 5 percent contamination are suitable for food-contact R_PET production; below 15 percent for industrial R_PET; below 30 percent for general industrial pellets; below 45 percent for DOWNCYCLING; above 45 percent are downgraded to thermal recovery. Process stability is managed by Statistical Process Control (SPC) over extruder torque, melt viscosity, and pellet weight deviation, measured every 30 minutes per the ISO 9001:2015 quality management framework.
Recovery flows frequently cross national borders. Transboundary movement of waste plastics, textiles, and electrical equipment is regulated under the 1989 Basel Convention. The Plastic Waste Amendments effective January 2021 brought mixed plastic waste and contaminated plastic waste under the Prior Informed Consent (PIC) procedure. WIA-ENE-023 envelopes for transboundary flows must carry the source_country, destination_country, and basel_consent_id fields, and envelopes missing PIC consent are rejected by importing hosts.
The Korean edition of this chapter contains an additional section on Korean infrastructure mapping, including the Korean Ministry of Environment Plastic Waste Resource Circulation Comprehensive Strategy, the operating roles of the Korea Resource Circulation Service Agency (KORA), the Korea Environment Corporation (KECO), the Korea Packaging Recycling Cooperative, the Korea Electronics Recycling Cooperative (KERC), the Korea Automobile Recycling Association (KARA), and the industrial chemical recycling facilities operated by SK geo centric (Ulsan, 320,000 t/yr from 2025), LG Chem (Dangjin, 100,000 t/yr), and Lotte Chemical (Yeosu, 110,000 t/yr). The Korea Environmental Industry and Technology Institute (KEITI) Type I Eco-Label certification system and the Korea Laboratory Accreditation Scheme (KOLAS) test laboratory accreditation under ISO/IEC 17025 are also covered in detail in that edition.
This chapter has covered the six branches of recycling technology and their quantitative metrics. MECHANICAL_RECYCLING is the mainstream pathway but is bounded by the five-cycle ceiling for PET. CHEMICAL_RECYCLING breaks that ceiling but consumes approximately 7-10 times more energy. THERMAL_RECYCLING is classified into RECYCLING or RECOVERY tier automatically by output type. BIOLOGICAL_RECYCLING covers organic streams and BIODEGRADABLE plastics. UPCYCLING and DOWNCYCLING are classified quantitatively by output-to-input unit price ratio. The chapter has further presented yield and residue calculation per EN 13430:2004, energy and CO2 calculation per ISO 14067:2018, closed-loop and open-loop distinction per ISO 14044:2006, and optical and AI-based sorting operations. The next chapter develops the EPR financial instruments that fund the six branches across the five waste streams covered by EPR schemes.