No - plastic liners are not accepted, even if they are compostable.
Compost Manufacturing Alliance – Windrow (CMA-W) Change
Approved Manufactured Compostable Products
The only manufactured compostable products that are accepted at the city's compost facility are those that are both Compost Manufacturing Alliance - Windrow (CMA-W) certified and made of fiber material. These products can be identified and purchased by using the resources provided below.
Helpful Resources
If you need assistance using either of these resources, please watch this tutorial video.
Background Information
As of January 1, 2024, the City of Ann Arbor and it's compost facility operator, WeCare Denali (WeCare), no longer accepts material that is only BPI certified. Instead, only selected products identified as being certified "CMA-W", short for Compost Manufacturing Alliance - Windrow, and made of fiber material will be accepted. Bamboo and palm leaf products are currently excluded as they do not break down within the same timeframes of other materials.
The change was necessary because:
- Compostable plastics can be nearly indistinguishable from traditional petroleum-based plastics, which leads to traditional plastics in the compost stream and compostable materials in the recycling stream.
- CMA certification adds a field test for compostability, in addition to lab testing, which ensures items break down appropriately in a real-world composting.
This change may be frustrating, especially for businesses, organizations or individuals who have stocks of this material. However, the benefits to improving our environment and in meeting the city's climate change goals are well worth the effort.
To help the community understand this shift, the city has:
This change may be frustrating, especially for businesses, organizations or individuals who have stocks of this material. However, the benefits to improving our environment and in meeting the city's climate change goals are well worth the effort.
To help the community understand this shift, the city has:
- held outreach and trainings to those most heavily invested in manufactured compostable products such as food businesses
- conducted community and outreach communications via print and digital channels
Webinar videos
- Why is the city switching to CMA-W certification?
- What's accepted and where do I get it?
- What is the CMA-W certification process?
- Who is Denali?
- I am a business, what does the commercial composting program look like?
The CMA-W Webinar slides (PDF) are available for viewing.
If you have a commercial property that is interested in compost service, visit our Commercial Compost Collection for Food Scraps webpage.
Frequently Asked Questions
How do I know if an item is compostable?
The CMA-W certified products are not branded as such. If the item says that it is compostable but looks like plastic, leave it out. If the item is paper or wood-based and says that it is compostable, then put it in.
Are napkins, paper towels, paper coffee filters and cardboard acceptable?
Yes - However, cardboard is better recycled and should only be included in small amounts.
Is plastic cutlery acceptable?
No - Plastic cutlery is not accepted, even if it is compostable.
Are there some plastics that are accepted in the compost?
No - Plastic causes serious litter and contamination problems at our compost site.
What can I use in place of biodegradable plastic bags?
We strongly encourage liner-less kitchen composter use, and to instead place a paper yard bag in the cart to prevent materials from sticking. If a liner is a must for a kitchen composter an unlined paper one is recommended.
When in doubt, throw it out!