compostable plastic cutlery decomposition test in … · requiring the use of compostable...

COMPOSTABLE PLASTIC CUTLERY DECOMPOSITION TEST IN AN

AGITATED, AERATED BAY TYPE COMPOSTING SYSTEM September 2014

Richard Nicoletti, PE BDP Industries – Compost Systems Manager (518) 695 6851

It is understood that food scraps for composting can contain significant quantities of contamination – with the primary contaminant being plastic film, packaging and cutlery. Many communities are requiring the use of compostable substitutes for these materials – typically compostable plastics. However there are some compostable plastic items that have proven to require extended periods of time to properly break down in composting processes. Particularly the thicker cutlery, in static type composting processes such as aerated static piles (ASP), tunnels or boxes.

In an effort to demonstrate the ability of our agitated bay type composting technology to adequately break down these more persistent compostable plastics, BDP recently performed a test at a compost acility that utilizes BDP’s compost agitators to compost a blend of wood shavings and biosolids. The technology is as represented in this schematic:

Tel: 518-695-6851 Fax: 518-695-5417 Email: [email protected]

BDP Industries, Inc. • 354 State Route 29 • Greenwich, NY 12834

As can be seen in photo 1, to create a worst case scenario we used a high temperature (200F rated) compostable plastic cutlery and placed them whole (unground) on the top surface of the compost pile in the front end of the bay. We placed approximately 200 pieces of cutlery in the 14 cubic yard charge at the front of the bay. This cutlery is approximately 6” long and according to the manufacturer’s website:

Our new utensils are made from TPLA (70% non GMO PLA and 30% talc.) They are also heat resistant up to 200 degrees F and are certified under ASTM-6400 standards and now have BPI Certification.

[Brand Name] TPLA utensils are compostable and biodegradable, and will take 120+ days to compost in a commercial composting. Home composting is not recommended and it may take 1 – 2 years to compost in a home composting system.

Photo 1 – Compostable Cutlery loaded in front of bay on top of compost material



During the 21 days in the bay the compost temperature ranged from 62C to 49C with an average of 54C. The material was agitated 18 times. The resulting approximate 10 cubic yard discharge material was subsequently screened (3/8” mesh). We found maybe 10 pieces in the screen overs pile. (See second photo). The pieces we recovered were extremely friable – could break them easily with fingers whereas the new cutlery was very pliable.

Photo 2 – Cutlery Pieces Recovered From Screening Overs

Note broken piece in front

Photo 3 - Finished Screening Unders (<3/8”)



Photo 4 – Screening Overs Pile (>3/8”)

BDP’s conclusion is that the agitated bay type technology is very effective at handling compostable plastic due to the frequent agitation process with the macerating effect of the agitator tines combined with the heat generation to achieve friability. Had we pre-ground the cutlery we doubt we would have found any recognizable cutlery pieces after the 21 days in the bay. Further decomposition in the 30 day Curing process should ensure essentially total decomposition provided the infeed mix has appropriate heat generating capability.

The plastic cutlery at 6” long posed no mechanical issues for the agitator. Plastic compostable (or even non compostable) film, properly pre-ground, poses no mechanical problems either for the agitator such as entanglement on drum tines as determined from other Municipal Solid Waste (MSW) compost facilities that utilize BDP equipment.

BDP wishes to thank the Town of Merrimack, NH and Jim Taylor - Assistant DPW for the use of their compost facility to perform this test

Note found cutlery pieces collected in center of pile.



compostable plastic cutlery decomposition test in … · requiring the use of compostable...

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