We launched our Send-Back Program last year, and have been overjoyed to see how many of our customers participated in this program. We love being able to offer an option for composting our bags for those of you who can’t compost yourself… and even moreso, we love seeing our customers go out of their way to participate in this program.
You may wonder - what happens to the bags after they get returned to Sun & Swell?
While our dream is to ultimately have our own Sun & Swell compost facility (someday!!), today we partner with a few amazing compost partners that compost used Sun & Swell bags for us.
In this blog, we share a little bit more about what happens after we get the bags back, and also share insights we gathered from the first test batch of compost created with bags from our Send-Back program. This first batch was composted in partnership with Soil Cycle, a non-profit community composter (who also happens to be one of our 1% for the Planet Partners).
What happens after used bags get returned to Sun & Swell?
After used bags get returned to us, we sort them, record what was sent back, then compile them in 20lb+ batches to ship off to a few various composting partners we have identified. One of those partners is Soil Cycle, who composted the first ever batch for us!
Before we share more about what we’ve learned so far partnering with Soil Cycle, first, a little more details about their organization and compost facility.
More about Soil Cycle and their compost facility:
Soil Cycle is a community composting nonprofit based in Missoula, MT. Their mission is to promote the natural food cycle by providing sustainable compost services and soil-based education.
Soil Cycle's operations, which are human-powered, consist of multiple methods of composting. Their main method of composting happens in large 4 foot square wooden bins that mimic a slightly larger version of your typical home compost system. This system relies on microbial heat (thermophilic composting) to break down organic materials and compostable packaging. The temperature of their 8 outdoor piles is measured daily to make sure they are reaching and maintaining optimal temperatures for decomposition.
Observations and Lessons Learned about Composting Sun & Swell bags with Soil Cycle
Soil Cycle started composting the Sun & Swell test pile the first of September 2021, allowing the decomposition process to finish in January 2022. Over the course of 4.5 months, packaging warped and slowly disintegrated as microbes heated up the compost pile. To increase surface area for better break-down, we first shredded materials with a household paper-shredded.
How did the Sun & Swell test pile vary from other compost piles?
Other compost piles at Soil Cycle are mainly made up of food waste, saw dust, and shredded paper. The Sun & Swell compost pile, also known as “Deborah,” contained 10% Sun & Swell packaging.
Compared to other compost piles, the Sun & Swell test pile:
- Took about 1 month longer to finish processing than usual compost piles. This is because compostable “plastics” take longer to break down than materials like food scraps.
- Remained at a fairly constant 140 degrees for much longer than our other piles. While it is easy to compost paper containers at home, compostable “plastics” require temperatures between 130 and 140 degrees, which causes materials to warp and quicken the process. On average, Soil Cycle’s compost bins stabilize and maintain 140-160 degree temperature for about a month before they begin the cool down process. The Sun & Swell test pile kept constant high temperatures for well over 2 months which was unusual.
- The pile was slightly darker in color than other piles. High temperatures generate humic acid, which enables plants to assimilate the nutrients in the compost. This humic acid adds a dark, almost black color to soils.
Why did the Sun & Swell test pile stay hotter longer, and lessons can be learned for anyone composting at home?
Our hypothesis is that the thermophilic microorganisms needed to process the complicated structure of the compostable packaging stayed present in the pile as long as they needed to break-down the materials, keeping the pile constantly hot.
The longer constant temperatures should not be considered a detractor. Compost temperature variability is an issue with smaller piles of compost. Stabilizing the temperature over longer periods will help stabilize temperatures in smaller composting systems allowing for more consistent production of humic acids. This can be a useful addition to compost heating systems and will help smaller composters or home systems in particular maintain good temperatures in their piles. This packaging had an unexpected perk and could be a good addition to home composting systems. Using a consistent hot pile, would allow you to harness heat as well and utilize it for heating a hot, greenhouse, or compost hot tub! (These are real things).
An aerated pile, with coiled water pipe in it with 10% Sun & Swell packaging could double the time a compost heating system could be used before needing to switch out compost piles. This greatly improves the usefulness of all kinds of compost heat applications and you'll get good quality compost out of it afterwards.
What happens with the compost that was created from the Sun & Swell test pile?
The compost made in the test pile will be hand sifted, bagged and returned to some of Soil Cycle’s 250 members that they collect food scraps from. They give back compost to members for free twice a year, in Spring and Fall.
Here’s a photo of our founder, Kate, with the compost created from this first batch.