Unlocking the Value of Plastics: A Comprehensive Guide to Resin Codes for MRFs
Understanding Resin Codes: What Every MRF Should Know About Recyclable Plastics
When it comes to maximizing plastic recovery and profitability, understanding resin identification codes (RICs) is crucial for every Material Recovery Facility (MRF). These resin codes, numbered #1 through #7, indicate the type of plastic used in everyday items and provide key information about their recyclability. However, not all plastics are created equal—some types have strong market demand and a well-established recycling process, while others present significant challenges.
In this article, we’ll break down each resin type, its common uses, market demand, recycling challenges, and practical steps to improve recovery rates and profitability.
Why Resin Codes Matter
Resin codes were developed in 1988 by the Society of the Plastics Industry (now known as the Plastics Industry Association) to help identify and categorize different types of plastics. This system makes it easier for recyclers to sort and process materials. Understanding these codes allows MRFs to improve sorting accuracy and efficiency, reduce contamination in bales, identify high-value plastics to prioritize, and meet buyer specifications to secure long-term contracts. Correctly sorting plastics can significantly impact an MRF’s profitability and strengthen its reputation with buyers and processors.
Additional Context: While resin codes help in identifying the type of plastic, they don’t always indicate whether a plastic is recyclable in standard systems. Factors such as contamination, additives, and multi-layer designs can complicate the recycling process.
1. PET (Polyethylene Terephthalate) – Resin Code #1
Common uses include water bottles, soda bottles, salad containers, and peanut butter jars. PET is one of the most recycled plastics globally and is known for its lightweight properties and transparency. The market demand for PET is high because it is widely used in food and beverage packaging and can be turned into fibers, containers, and packaging films.
Challenges: Contamination from unrinsed bottles, caps, and food residue remains a significant issue. Additionally, colored PET bottles (e.g., green or blue) have less market value because they are harder to process into neutral or clear end products.
Pro Tip: Focus on collecting clear PET bottles, as they fetch higher prices. Encourage public education campaigns that emphasize rinsing bottles before disposal. Some municipalities have seen contamination rates drop by 15-20% after implementing educational programs (source: Recycling Partnership). Additionally, consider partnering with brands that use PET that’s free from colorants or additives, making the material easier to recycle.
2. HDPE (High-Density Polyethylene) – Resin Code #2
Common uses include milk jugs, detergent bottles, shampoo bottles, and grocery bags. HDPE is highly valued for its durability and resistance to chemical wear, making it one of the most recyclable and profitable plastics. The demand for natural (unpigmented) HDPE, such as clear milk jugs, is particularly high.
Challenges: Colored HDPE, such as detergent and shampoo bottles, is often sold at a lower price due to limitations in downstream applications. HDPE can also become contaminated if mixed with plastic films or non-compatible resin types.
Pro Tip: Separate natural HDPE from colored HDPE to maximize revenue. Partner with local businesses to increase the collection of natural HDPE. Maintain consistent bale density to meet buyer specifications and ensure that HDPE films (e.g., grocery bags) are kept out of the HDPE rigid plastic stream to prevent contamination.
3. PVC (Polyvinyl Chloride) – Resin Code #3
Common uses include pipes, vinyl flooring, window frames, and some food packaging. PVC is known for its versatility and strength but is one of the least recycled plastics due to its chemical complexity and hazardous additives.
Challenges: PVC can release toxic chlorine gas during the recycling process, making it dangerous for standard MRFs to handle. Cross-contamination with other plastics can also ruin entire bales.
Pro Tip: Avoid mixing PVC with other plastics to prevent contamination. Communicate clearly with suppliers and collection partners that PVC is non-recyclable in most programs. Encourage consumers to dispose of PVC through designated drop-off points for specialized recycling.
4. LDPE (Low-Density Polyethylene) – Resin Code #4
Common uses include plastic bags, shrink wrap, and sandwich bags. LDPE is flexible and used in a wide range of applications, especially films and wraps. However, LDPE films often tangle in MRF sorting equipment, causing operational delays.
Challenges: The recycling infrastructure for LDPE films is not as developed as it is for rigid plastics. Contamination is also a significant concern due to food residue and improper disposal.
Pro Tip: Partner with specialized film recyclers to create a secondary revenue stream. Encourage residents and businesses to use drop-off programs for plastic films to keep them out of curbside collections. Some programs, such as grocery store take-back initiatives, have been successful in creating clean LDPE film streams.
5. PP (Polypropylene) – Resin Code #5
Common uses include yogurt containers, bottle caps, straws, and takeout containers. Polypropylene (PP) is one of the fastest-growing markets in the recycling industry due to its versatility and strength. It is commonly recycled into items such as automotive parts, textiles, and storage containers.
Challenges: PP can be difficult to identify and sort due to its similarity in appearance to other plastics. Small PP items like bottle caps and lids can get missed in the sorting process or fall through conveyor belts.
Pro Tip: Invest in optical sorting systems that can distinguish PP from other resins. Collaborate with buyers who can accept mixed rigid PP plastics for further processing. Educate your suppliers to ensure that small PP items are included in the right stream and not discarded.
6. PS (Polystyrene) – Resin Code #6
Common uses include foam packaging, disposable cups, and takeout containers. Polystyrene, especially expanded polystyrene (EPS), is lightweight and commonly used in packaging. However, it has a very low recycling rate due to its fragile nature and contamination issues.
Challenges: EPS is often contaminated with food residue and is difficult to compact into transportable bales. Additionally, some jurisdictions have banned the use of EPS due to its environmental impact.
Pro Tip: Avoid accepting expanded polystyrene unless your facility has access to a dedicated EPS recycling program. Encourage local businesses to switch to compostable or recyclable alternatives to reduce EPS in the waste stream.
7. Other (Mixed Plastics) – Resin Code #7
Common uses include multi-layer food pouches, bioplastics, and some large water jugs. The “Other” category is a catch-all for plastics that do not fit into the first six resin types. This category includes bioplastics, polycarbonate, and multi-layer plastics, all of which are difficult to recycle.
Challenges: The variety of materials in the #7 category makes it difficult to sort and recycle consistently. Many #7 plastics require specialized chemical recycling processes.
Pro Tip: Partner with chemical recyclers that can process mixed plastics. Educate suppliers about the limitations of #7 plastics to reduce their presence in collection streams. When possible, identify and prioritize subcategories of #7 plastics that have a viable recycling market.
The Path to Higher Plastic Recovery Rates
Understanding resin codes is about more than just sorting—it’s about making informed decisions that improve bale quality, increase market value, and build stronger relationships with buyers. By investing in better sorting technologies, maintaining clear communication with suppliers, and targeting high-demand resins, MRFs can capture more value and contribute to a stronger circular economy.
At Midas Peak, we’re committed to helping MRFs improve their operations and connect with buyers who value high-quality, sustainable materials. Contact us today to learn more about how we can help you optimize your plastic recovery and grow your revenue.
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