Alex, my son, and his partner, Lisa, are coming to see us later today. They arrived in Portland on Sunday, 11th but first of all wanted to see Yellowstone.
Every week, millions of Americans toss their recyclables into a single bin, trusting that their plastic bottles, aluminum cans and cardboard boxes will be given a new life.
But what really happens after the truck picks them up?
Plastics are among the biggest challenges. Only about 9% of the plastic generated in the U.S. actually gets recycled, according to the Environmental Protection Agency. Some plastic is incinerated to produce energy, but most of the rest ends up in landfills instead.
A breakdown of U.S. recycling by millions of tons shows about two-thirds of all paper and cardboard gets a second life, but only about a third of metal, a quarter of glass and less than 10% of plastics do. Alex Jordan/University of Wisconsin-Stout
So, what makes plastic recycling so difficult? As an engineer whose work focuses on reprocessing plastics, I have been exploring potential solutions.
How does single-stream recycling work?
In cities that use single-stream recycling, consumers put all of their recyclable materials − paper, cardboard, plastic, glass and metal − into a single bin. Once collected, the mixed recyclables are taken to a materials recovery facility, where they are sorted.
First, the mixed recyclables are shredded and crushed into smaller fragments, enabling more effective separation. The mixed fragments pass over rotating screens that remove cardboard and paper, allowing heavier materials, including plastics, metals and glass, to continue along the sorting line.
The basics of a single-stream recycling system in Pennsylvania. Source: Van Dyk Recycling Solutions.
Magnets are used to pick out ferrous metals, such as steel. A magnetic field that produces an electrical current with eddies sends nonferrous metals, such as aluminum, into a separate stream, leaving behind plastics and glass.
The glass fragments are removed from the remaining mix using gravity or vibrating screens.
That leaves plastics as the primary remaining material.
While single-stream recycling is convenient, it has downsides. Contamination, such as food residue, plastic bags and items that can’t be recycled, can degrade the quality of the remaining material, making it more difficult to reuse. That lowers its value.
Having to remove that contamination raises processing costs and can force recovery centers to reject entire batches.
Plastic bags, food residue and items that can’t be recycled can contaminate a recycling stream. City of Greenville, N.C./Flickr
Which plastics typically can’t be recycled?
Each recycling program has rules for which items it will and won’t take. You can check which items can and cannot be recycled for your specific program on your municipal page. Often, that means checking the recycling code stamped on the plastic next to the recycling icon.
These are the toughest plastics to recycle and most likely to be excluded in your local recycling program:
Symbol 3 – Polyvinyl chloride, or PVC, found in pipes, shower curtains and some food packaging. It may contain harmful additives such as phthalates and heavy metals. PVC also degrades easily, and melting can release toxic fumes during recycling, contaminating other materials and making it unsafe to process in standard recycling facilities.
Symbol 4 – Low-density polyethylene, or LDPE, is often used in plastic bags and shrink-wrap. Because it’s flexible and lightweight, it’s prone to getting tangled in sorting machinery at recycling plants.
Symbol 6 – Polystyrene, often used in foam cups, takeout containers and packing peanuts. Because it’s lightweight and brittle, it’s difficult to collect and process and easily contaminates recycling streams.
Which plastics to include
That leaves three plastics that can be recycled in many facilities:
Symbol 5 – Polypropylene, PP, used in products such as pill bottles, yogurt cups and plastic utensils.
However, these aren’t accepted in some facilities for reasons I’ll explain.
Taking apart plastics, bead by bead
Some plastics can be chemically recycled or ground up for reprocessing, but not all plastics play well together.
Simple separation methods, such as placing ground-up plastics in water, can easily remove your soda bottle plastic (PET) from the mixture. The ground-up PET sinks in water due to the plastic’s density. However, HDPE, used in milk jugs, and PP, found in yogurt cups, both float, and they can’t be recycled together. So, more advanced and expensive technology, such as infrared spectroscopy, is often required to separate those two materials.
Once separated, the plastic from your soda bottle can be chemically recycled through a process called solvolysis.
It works like this: Plastic materials are formed from polymers. A polymer is a molecule with many repeating units, called monomers. Picture a pearl necklace. The individual pearls are the repeating monomer units. The string that runs through the pearls is the chemical bond that joins the monomer units together. The entire necklace can then be thought of as a single molecule.
During solvolysis, chemists break down that necklace by cutting the string holding the pearls together until they are individual pearls. Then, they string those pearls together again to create new necklaces.
Other chemical recycling methods, such as pyrolysis and gasification, have drawn environmental and health concerns because the plastic is heated, which can release toxic fumes. But chemical recycling also holds the potential to reduce both plastic waste and the need for new plastics, while generating energy.
The problem of yogurt cups and milk jugs
The other two common types of recycled plastics − items such as yogurt cups (PP) and milk jugs (HDPE) − are like oil and water: Each can be recycled through reprocessing, but they don’t mix.
If polyethylene and polypropylene aren’t completely separated during recycling, the resulting mix can be brittle and generally unusable for creating new products.
Chemists are working on solutions that could increase the quality of recycled plastics through mechanical reprocessing, typically done at separate facilities.
One promising mechanical method for recycling mixed plastics is to incorporate a chemical called a compatibilizer. Compatibilizers contain the chemical structure of multiple different polymers in the same molecule. It’s like how lecithin, commonly found in egg yolks, can help mix oil and water to make mayonnaise − part of the lecithin molecule is in the oil phase and part is in the water phase.
In the case of yogurt cups and milk jugs, recently developed block copolymers are able to produce recycled plastic materials with the flexibility of polyethylene and the strength of polypropylene.
Improving recycling
Research like this can make recycled materials more versatile and valuable and move products closer to a goal of a circular economy without waste.
However, improving recycling also requires better recycling habits.
You can help the recycling process by taking a few minutes to wash off food waste, avoiding putting plastic bags in your recycling bin and, importantly, paying attention to what can and cannot be recycled in your area.
I was going through some files yesterday and found many photographs taken by me.
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These were taken in 2018 which was when my son, Alex, and his partner, Lisa, came over to see us.
Here is the opening part of Wikipedia writing about Crater Lake:
Crater Lake (Klamath: Giiwas)[2] is a volcanic crater lake in south-central Oregon in the WesternUnited States. It is the main feature of Crater Lake National Park and is a tourist attraction for its deep blue color and water clarity. The lake partly fills a 2,148-foot-deep (655 m) caldera[3] that was formed around 7,700 (± 150) years ago[4] by the collapse of the volcano Mount Mazama. No rivers flow into or out of the lake; the evaporation is compensated for by rain and snowfall at a rate such that the total amount of water is replaced every 150 years.[5] With a depth of 1,949 feet (594 m),[6] the lake is the deepest in the United States. In the world, it ranks eleventh for maximum depth, as well as fifth for mean depth.
This article was published in The Conversation last Thursday, the 6th March, 2025.
Where we live in rural Southern Oregon is glorious and photos of our locale have been published before. However, I wanted to share this article with you all.
ooOOoo
Butterflies declined by 22% in just 2 decades across the US – there are ways you can help save them
We found declines in just about every region of the continental U.S. and across almost all butterfly species.
Overall, nearly one-third of the 342 butterfly species we were able to study declined by more than half. Twenty-two species fell by more than 90%. Only nine actually increased in numbers.
West Coast lady butterflies range across the western U.S., but their numbers have dropped by 80% in two decades. Renee Las Vegas/Wikimedia Commons, CC BY
Some species’ numbers are dropping faster than others. The West Coast lady, a fairly widespread species across the western U.S., dropped by 80% in 20 years. Given everything we know about its biology, it should be doing fine – it has a wide range and feeds on a variety of plants. Yet, its numbers are absolutely tanking across its range.
Why care about butterflies?
Butterflies are beautiful. They inspire people, from art to literature and poetry. They deserve to exist simply for the sake of existing. They are also important for ecosystem function.
Butterflies are pollinators, picking up pollen on their legs and bodies as they feed on nectar from one flower and carrying it to the next. In their caterpillar stage, they also play an important role as herbivores, keeping plant growth in check.
A pipevine swallowtail caterpillar munches on leaves at Brookside Gardens in Wheaton, Md. Herbivores help keep plant growth in check. Judy Gallagher/Wikimedia Commons, CC BY
Butterflies can also serve as an indicator species that can warn of threats and trends in other insects. Because humans are fond of butterflies, it’s easy to get volunteers to participate in surveys to count them.
The annual North American Butterfly Association Fourth of July Count is an example and one we used in the analysis. The same kind of nationwide monitoring by amateur naturalists doesn’t exist for less charismatic insects such as walking sticks.
What’s causing butterflies to decline?
Butterfly populations can decline for a number of reasons. Habitat loss, insecticides, rising temperatures and drying landscapes can all harm these fragile insects.
A study published in 2024 found that a change in insecticide use was a major factor in driving butterfly declines in the Midwest over 17 years. The authors, many of whom were also part of the current study, noted that the drop coincided with a shift to using seeds with prophylactic insecticides, rather than only spraying crops after an infestation.
The Southwest saw the greatest drops in butterfly abundance of any region. As that region heats up and dries out, the changing climate may be driving some of the butterfly decline there. Butterflies have a high surface-to-volume ratio – they don’t hold much moisture – so they can easily become desiccated in dry conditions. Drought can also harm the plants that butterflies rely on.
Only the Pacific Northwest didn’t lose butterfly population on average. This trend was largely driven by an irruptive species, meaning one with extremely high abundance in some years – the California tortoiseshell. When this species was excluded from the analyses, trends in the Pacific Northwest were similar to other regions.
The California tortoiseshell butterfly can look like wood when its wings are closed, but they’re a soft orange on the other side. Walter Siegmund/Wikimedia Commons, CC BY-SA
When we looked at each species by its historical range, we found something else interesting.
Many species suffered their highest losses at the southern ends of their ranges, while the northern losses generally weren’t as severe. While we could not link drivers to trends directly, the reason for this pattern might involve climate change, or greater exposure to agriculture with insecticides in southern areas, or it may be a combination of many stressors.
There is hope for populations to recover
Some butterfly species can have multiple generations per year, and depending on the environmental conditions, the number of generations can vary between years.
This gives me a bit of hope when it comes to butterfly conservation. Because they have such short generation times, even small conservation steps can make a big difference and we can see populations bounce back.
The Karner blue is an example. It’s a small, endangered butterfly that depends on oak savannas and pine barren ecosystems. These habitats are uncommon and require management, especially prescribed burning, to maintain. With restoration efforts, one Karner blue population in the Albany Pine Bush Preserve in New York rebounded from a few hundred individuals in the early 1990s to thousands of butterflies.
Similar management and restoration efforts could help other rare and declining butterflies to recover.
What you can do to help butterflies recover
The magnitude and rate of biodiversity loss in the world right now can make one feel helpless. But while national and international efforts are needed to address the crisis, you can also take small actions that can have quick benefits, starting in your own backyard.
Butterflies love wildflowers, and planting native wildflowers can benefit many butterfly species. The Xerces Society for Invertebrate Conservation has guides recommending which native species are best to plant in which parts of the country. Letting grass grow can help, even if it’s just a strip of grass and wildflowers a couple of feet wide at the back of the yard.
A patch of wildflowers and grasses can become a butterfly garden, like this one in Townsend, Tenn. Chris Light, CC BY-SA
Supporting policies that benefit conservation can also help. In some states, insects aren’t considered wildlife, so state wildlife agencies have their hands tied when it comes to working on butterfly conservation. But those laws could be changed.
The federal Endangered Species Act can also help. The law mandates that the government maintain habitat for listed species. The U.S. Fish and Wildlife Service in December 2024 recommended listing the monarch butterfly as a threatened species. With the new study, we now have population trends for more than half of all U.S. butterfly species, including many that likely should be considered for listing.
With so many species needing help, it can be difficult to know where to start. But the new data can help concentrate conservation efforts on those species at the highest risk.
I believe this study should be a wake-up call about the need to better protect butterflies and other insects – “the little things that run the world.”
Learning from Dogs 
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