JOSHUA TREE, Calif. — Soph Nielsen was sewing garbage onto her black T-shirt (a chicken wing, a crushed Bud Light can, a plastic fork) and struggling to attach a snarl of crusty pad thai.

“This is to get people to see the trash,” she said, her fingers slick with grease. “We don’t want to be the invisible janitors.” With her distinctive appliqués, that was unlikely.

It was the last day of the Joshua Tree Music Festival, a family-friendly event of didgeridoo sound baths, yoga, crafts, electronica and other familiar fare held at a dusty desert campground for three days in October. Ms. Nielsen, a 25-year-old artist whose medium is trash, was one of 20-odd Trash Pirates working the event.

The Pirates are a loose collective of waste management specialists, to borrow a phrase from Tony Soprano, who make sure events are as sustainable as possible through recycling and composting. They also educate attendees about how to do both properly.

Garbage has long been the uncomfortable fallout of the festival world, and as these gatherings multiply like glow sticks at a Phish concert, stretching the season into a year-round party (hola, Costa Rica), its impact has roused young artists and activists like Ms. Nielsen.

Most Pirates start out as volunteers, helping with trash or performing other tasks so as to attend for free. Then they have their “trash moment,” as the Pirates put it, the epiphany that turns volunteer work into a career, and trash into a calling.

“Your first experience of the mass of it, whether it’s loading dumpsters onto a trailer or driving out to the event grounds when everyone is gone and it’s a sea of trash, is an existential crisis,” Ms. Nielsen said. “You are baptized into compost.”

“You’re either in or you’re out,” she added, echoing the rallying cry of a long-ago counterculture movement that involved a bus, “and it becomes a way of life.”

The events themselves — both community-minded and escapist — are morphing into trash camps: days-long immersions into the politics of waste, with lectures and workshops on developing your garbage-handling skills along with your yoga practice.

Some trash stats are in order. In 2017, according to an environmental impact report, Coachella, in Indio, Calif., was generating over 100 tons of trash each day. Many events are now committed to becoming zero-waste endeavors, or as close to it as possible. High “diversion” rates (the percentage of waste not sent to the landfill) are badges of honor. Last spring, the Trash Pirates brought the Joshua Tree Music Festival’s rate up to 77 percent.

In 2017, Coachella’s diversion rate was just 20 percent, apparently because attendees weren’t using the recycling bins. Veterans of Burning Man and other festivals learn acronyms like MOOP, for “Matter Out of Place,” an umbrella term for trash and anything else that doesn’t occur naturally on a site; cigarette butts, broken tents and human waste are some common examples.

Burning Man has a “Leave No Trace” ethos, but the messy camps of bad Burners are called out each year on the festival’s MOOP Map in the hope that public shaming will be a deterrent next time around.

‘Shepherds of the “Away’’’

While there are many waste organizations dedicated to mitigating the environmental impact of such gatherings, the Trash Pirates are distinguished by their zeal and their punk aplomb.

Take Moon Mandel, 24, a filmmaker and Trash Pirate who was managing the operations that weekend at Joshua Tree. Mx. Mandel is nonbinary, and with their bright orange jumpsuit emblazoned with patches stitched with trash graphics (the recycling whorl and other insignia) they looked like an indie Eagle Scout.

As Oscar the Grouch sang his gruff-voiced hymn “I Love Trash,” one of many trash-friendly songs on the Pirates’ playlist, Mx. Mandel said: “It’s very important for people to see the work we do and understand the human scope of it. We are trying to alter the cultural norms of a throwaway society. We teach them that there’s no ‘away.’ We are the shepherds of the ‘away’ and it’s being buried inside the earth forever.”

And so Mx. Mandel performed trash collections, dancing with colleagues as Oscar warbled under a festive tent with gaily painted bins, and sorting garbage (earning $5 a bag) for those campers too busy or negligent to do it themselves.

To attendees who had dutifully separated their food scraps and recyclables and were tipping them into the appropriate bins, Mx. Mandel called out a hearty, “Yarg!” their preferred Pirate cheer.

“Thank you for composting!” Mx. Mandel praised a young woman scraping scrambled eggs out of a frying pan, and then recited some recycling basics: “You can’t compost paper with too much printing on it, or recycle greasy paper. Single-use bags can be taken to supermarkets in California for recycling, so we are collecting them. Make sure everything is clean. You don’t need to rinse your soda or beer cans. But if your stuff is covered in yogurt, it’s not going to be recycled.”

Mx. Mandel has a policy about not working festivals where organizers are charging for water. “The decommodification of water is one of my core beliefs,” they said.

Mx. Mandel was particularly proud of their cigarette-butt program. For the last two years, they have been collecting butts (200,000 and counting, they said) at festivals and sending them to TerraCycle, a company that teams with manufacturers and retailers to recycle or upcycle all manner of products and materials, including action-figure toys, backpacks and toothbrushes. Cigarette butts are turned into plastic pallets; the tobacco is composted.

Sarah Renner, the operations and site manager for the Joshua Tree Music Festival, wrote in an email that the Trash Pirates are “the down and dirty, real as can be, heroes of the event world.”

The Pirates have handled her festival’s waste for the last four years, sweeping, handing out bags and painting barrels with children. “They don’t just pull trash bags and sort recycling,” she said. “They are on a mission to change the way people think while getting everything to where it needs to go.””

The work is brutal. Heat stroke, sunburn, cuts and bruises are common hazards, as is a dousing with trash juice: the pungent slurry that pours from a trash can and into your armpits when you’re hoisting it over your head.

Close-toed boots are encouraged, but don’t always protect. Mx. Mandel’s foot was sliced open, they said, this past February at a festival in Costa Rica by a severed iguana hand that pierced their boot, but most dangers are what you’d think: nails, screws, shards of glass.

Tools of the trade include MOOP sticks, which are long claws for grabbing trash without having to bend over. These are light and rather delicate, with a nice action, and are precise enough to pick up a grain of rice.

Hand sanitizer and liquid soap are requirements; one Pirate, Moose Martinez, had a Purell bottle clipped to the strap of his over-the-shoulder water bag. Work gloves and thin blue food service gloves are part of the uniform, but many of the Pirates were working in their bare hands.

“We call that raw-dogging,” said Luke Dunn, 33, a musician and preschool teacher, as a colleague with clean hands fed him a chocolate-chip cookie. “You try not to touch your face, you wash a lot.”

On the Pirates’ Facebook page, “Trash Pirates and Waste Naughts,” with over 4,000 followers, they share job tips (a recent post was for waste management at McMurdo Station in Antarctica); inspiration (“It’s Called Garbage Can, Not Garbage Cannot”); and education (news clips on California’s recycling woes and posts reviewing the best trash bags or instructions on how to make compostable confetti out of leaves with a hole puncher).

One long thread discussed cleaning up glitter, a particular scourge of Gay Pride parades.

‘The Lost Boys’

The Trash Pirates formed six years ago when two friends, Caleb Robertson, now 26, and Kirk Kunihiro, 29, then living in the San Francisco Bay Area, wanted to go to festivals for free.

While volunteering for the green teams, as they are called, of these gatherings, Mr. Robertson said, “We came to realize that there was a way to express our zero-waste passions within the event industry.”

They learned their craft at Green Mary, a two-decades-old company dedicated to making events sustainable that was founded by Mary Munat, an environmental activist and former Army reservist.

“They are fast, hard-working, green-hearted people,” she said of the Pirates. “I love their energy and greenness, and I am so glad my age-old eco-passions gave birth to so many little green pirates.”

The Trash Pirates was a nickname they gave each other early on, when festivals were more haphazard, and it stuck. In the beginning, Mr. Robertson, said “It was more seat-of-the-pants. Many of us were living out of our vehicles. That’s the thing: Trash can attract people who don’t feel like they have a place to go, giving people purpose in a space where they had none. Kind of like the Lost Boys. People are interested in the party, but it becomes empty if you don’t have a purpose.”

Next year, they hope to work upward of 30 events. “The work isn’t going to stop, I’m almost scared of it,” Mr. Robertson said, adding that he and many of his colleagues are looking to expand beyond the festivals and tackle community projects in Los Angeles, where he now lives, and beyond.

Mx. Mandel is devoted to filmmaking; Ms. Nielsen to art and activism. “But we are all still united by trash,” Mr. Robertson said. “We recognize that festivals are a stage and a platform to reach people, but we also know that it’s just a Band-Aid and the best thing we can do is to concentrate on government policies and community work.”

Mr. Kunihiro, who also lives in Los Angeles, started his own waste-consulting business, which includes a waste sampling service that analyzes the composition of waste streams — work that makes festival trash seem as clean and fresh, he said, as birthday cake.

He has led tours for fourth graders of recycling plants in the Bay Area; at Joshua Tree, his water bottle was a tiny blue toy recycling bin, a gift from his mother.

Another Pirate, Stephen Chun, talked about the awkward moment when he is asked what he does for a living. “A lot of people are like, ‘Huh, that’s nice. Good for you,” he said. “The feedback over time goes from being, ‘Oh, you’re the trash guy’ to, ‘Oh, you’re a hero.’ Now I say I’m a zero-waste events consultant.”

Ms. Munat said, “People see us going through the recycling and offer us their sandwiches. And we’re like, ‘No, it’s O.K., we’re getting paid.’”

Because trash is ascendant as a problem and a paradigm, it continues to grow as a métier. “In 1995, when I first starting teaching about waste, it was a boutique subject and not considered appropriate for academic study,” said Robin Nagle, a professor of anthropology and environmental studies at New York University who specializes joyfully in garbage.

She has been anthropologist-in-residence at the New York City Department of Sanitation for more than a decade; her book “Picking Up: On the Streets and Behind the Trucks With the Sanitation Workers of New York City” was published in 2013. Professor Nagle is a founder of what’s known as discard studies, a new interdisciplinary field of research examining waste politically, culturally and economically.

“You can take any piece of trash as an object in the world and track it from its raw materials though its journey into the marketplace as a commodity,” she said. “At any of those points it will connect not just to the proliferation of garbage as a form of pollution but a host of any other environmental crises including the big megillah that is climate change.”

Of the Trash Pirates she said, “They are pushing boundaries in wonderful ways. I would be curious to see what they’re doing in 20 years. Do they bounce from this ebullient, youthful thing to something more settled? And will the planet be even closer to the brink of destruction?”

We shall see, but in the meantime, as is their practice, the Pirates swept the Joshua Tree Music Festival campgrounds clean by forming a MOOP line, as it’s known, with each Pirate three to four feet apart and armed with a MOOP stick and a bucket, and moving from the perimeter to the center.

Mx. Mandel said, “Like one amoeba we slowly devour the MOOP.”