You clean, we'll sort!

We believe in recycling. All RecycleSmart blue cart materials are sent to the franchised processing facility, Mt. Diablo Resource Recovery (MDRR), in Pittsburg, CA. MDRR has invested in state-of-the-art technology to make sure recycling is easier for our community and our planet. It all starts with YOUR empty, clean, and dry blue cart materials. Let's see how Ali the Aluminum can gets processed at the facility…

Red cartoon aluminum can named Ali is smiling and waving.
Ali and her two aluminum can friends are on a conveyor belt on their way to get sorted.

First, recyclables (like Ali) are carried across a sorting line where staff members hand pick out any trash.

A magnet picks up metal objects, but Ali and her friends remain on the conveyor belt.

Next, a magnet picks up the tin cans and other metal objects—but not Ali, since aluminum isn't naturally magnetic!

Blow dryer air pushes paper away from Ali and her friends.

Now it's time for a blow dry! Jets of air push paper and cardboard away to be baled in a different area.

Ali and her friends take a selfie.

Say cheese! Optical sorters find and remove anything remaining that cannot be recycled.

Ali and her aluminum can friends shake from the Eddy Current.

Ali's ready for her appointment in the Eddy Current, a machine that makes her atoms wiggle so she becomes magnetic!

Ali and friends are clean after their magnetic massage.

During her magnetic massage, the labels and dye on Ali and her friends are removed. Now they can join other cans to start their new life!

Sorting process do's & don'ts

Recyclables move on a conveyor belt. Knotted piece of rope with a frayed end

Even though Mt. Diablo Resource Recovery has the finest sorting technology, what you put in the blue cart matters! Some items can create a lot of grief in the sorting process.

These should stay OUT of the blue recycling cart:

  • Anything with food residue like takeout containers, pizza boxes or jars. Any kind of goop can contaminate other items in a cart. Uncoated food-soiled paper can go in the green organics cart!
  • Items like rope, hoses or wires can wrap around the machinery during the sorting process. Tangles can create safety hazards for people working, and even cause the machinery to shut down.
  • Polystyrene foam, otherwise known as styrofoam, goes in the black landfill cart. Look for—and request— eco-friendly packaging.

Here's what CAN be recycled:

  • Empty, clean and dry plastic, glass and metal bottles, jars, aluminum and steel cans, clean foil, detergent and soap containers (keep the lids on!).
  • Clean and loose paper including cardboard, paper bags, newspapers, paper and envelopes.

It's important to make sure your items are empty, clean and dry when they go into the blue cart. It helps the machine capture all those good recyclables! For more recycling information, please go to

How it works

Check out the mega machine that sorts your recyclables!

Crumpled empty blue aluminum can.
Diagram of Mt. Diablo Resource Recovery Machine with recycling sorting steps.

Metering Bin

Provides an even, steady flow of material into the system, with help from MDRR staff


OCC Separator®

Separates cardboard from paper, containers and smaller scrap items


Debris Roll Screen®

This ramp with holes in it lets fine materials fall while paper and containers roll up


Polishing Screen #1

Separates medium-sized (6-12”) mixed paper from containers an scrap materials


Polishing Screen #2

Separates small (2-6”) mixed paper, containers and scrap materials


NRT Optical Sorter #1

Recovers small cardboard


NRT Optical Sorter #2

Near-infrared technology removes any remaining contaminants from mixed paper



Attracts and pulls out materials containing iron (like steel cans)


NRT Optical Sorter #4

Separates plastics, like food and drink containers, or cleaning products


NRT Optical Sorter #5

Recovers PET plastics


Eddy Current Separator

Activates electrons in aluminum to capture them with magnetism



Compresses recyclables into bales, ready for shipping

Scholars all-in for recycling

Gold star sticker. RecycleSmart scholarship winner Sophia. Gold star sticker. RecycleSmart scholarship winner Aya. Gold star sticker. RecycleSmart scholarship winner Devon. Gold star sticker.

Congratulations to our 2022 Scholarship winners! This year, RecycleSmart awarded scholarships to three outstanding students for leading recycling and composting initiatives at their schools. These students continue working towards sustainability and bringing positive change to their communities.

Sofia Gonzalez

Sophia was the Environmental Club leader at Acalanes High School and a RecycleSmart school intern! She educated fellow students about the benefits of sorting their waste and reducing what goes to the landfill by organizing a successful clothing drive. This fall, she will study Biology at UC Davis.

Aya Banaja

Aya was also a RecyleSmart school intern and Green Team member, and helped launch a campus-wide recycling and composting program at Las Lomas High. When she moved and attended Miramonte High, she collaborated with team members to host a virtual Earth Day Summit and created a Sorting 101 video to educate the broader Central Contra Costa community. She plans to attend Saint Mary’s College to study psychology this fall.

Devon Bradley

Devon is the founder and leader of the Miramonte Environmental Solutions Club and Project HEART. Devon focused on improving sorting and reducing waste at his school, which resulted in a 75% diversion rate for Miramonte High School! In August 2021, he helped influence the Orinda City Council to ban polystyrene. Devon will continue his journey this fall studying climate science at UCLA.

If you or someone you know is a stellar recycling scholar, visit to learn about scholarships for Spring 2023.

A tip from Lewis A., Walnut Creek

A note to my fellow coffee lovers

Hands putting a reusable coffee mug in a canvas tote bag.

My local coffee shop is encouraging customers to bring their own mugs by offering a 10 cent discount.

As a big coffee lover, I was so excited to hear I could get my favorite drink for less! I don't like having to use disposable cups when I pick up coffee on the go. I've been bringing my favorite mug to this coffee shop and I've noticed others are starting to do the same.

I've also heard that some restaurants allow customers to bring their own to-go containers. That's definitely a step up from coffee mugs and a great way to reduce waste.

So, fellow coffee lovers: let's keep our waste low with our cup of Joe!

Editor's note: CA State Law AB 619 allows consumers to bring their own clean, reusable food and beverage containers for takeout orders and leftovers (as long as they follow all sanitary guidelines). More at

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I spy

Can you sort these things? Count each item above and write the number in the box below. Check out our kids recycling sorting game at

Image of the Kids Corner sorting activity.

Click the image above to print out at full size.

A clean glass bottle, A peach pit, and a milk jug with blue cap.