Municipal Solid Waste Samples and Testing Procedure 

Sources

The team has two main sourcing strategies for our MSW simulation: plastic the team has personally collected, and recycling from around UK's campus. The team asked the recycling department about the best avenue for obtaining recycled plastic, and they suggested to take trash bags directly from the sorted plastic recycling bins. This will be easier and safer to collect than taking trash bags and less time will be wasted sorting through them for plastic. The team's personal gathering will supplement the recycling collection to ensure that a large variation of plastic waste is tested. 

Type 

There are 7 primary types of plastic, Polyethylene Terephthalate (PET or PETE), High-Density Polyethylene (HDPE), Polyvinyl Chloride (PVC or Vinyl), Low-Density Polyethylene (LDPE), Polypropylene (PP), Polystyrene (PS or Styrofoam), and others (A&C Plastics Inc., n.d.). We will be looking more specifically at the plastics which are most commonly thrown away, especially items which are considered single use plastic. These include many PVC, PET, HDPE, and LDPE products. These products will range from beverage containers, to general waste from products (such as food packaging), to jugs from various applications. The team will define the plastic types involved as waste is tested, and monitor to ensure there is an even distribution of types. This will make certain there is ample testing of the device's capabilities. 

Shredder and grinding testing will consist of both mixed plastic and individual plastic testing. The team will look for product inconsistencies among type, and eliminate any plastics which pose a threat to the machine function. Some plastics which have already been identified as a potential concern include cling wrap and  grocery bags. The team will test these and other plastics to ensure that they can be introduced by the user. 

Addressing Contamination Variation

The Environmental Protection Agency (EPA) defines MSW as the following "Municipal Solid Waste (MSW)—more commonly known as trash or garbage—consists of everyday items we use and then throw away, such as product packaging, grass clippings, furniture, clothing, bottles, food scraps, newspapers, appliances, paint, and batteries." (EPA, 2016). Since the plastic samples are obtained primarily from recycling, it will only be coming in contact with other plastics. This means to ensure the decontamination device can work in the full capacity needed, the plastic tested on the device should still come in contact with these other waste streams. 

In order to simulate the plastic being actual municipal solid waste, the team will add contaminants to the plastic. The team will try to include a variety of waste in the experiment, in ratios guided by the EPA's definition (Figure 1). Yard trimmings, food, and the "other" categories are identified as wastes which would leave lingering residue on a plastic waste, so they will constitute the wastes added. Artificial contamination is something correspondents from the National Idaho Laboratory have recently begun pursuing because they also obtain their plastic from a less contaminated source.  They suggested quantifying contaminants by mass; record weight of material before washing and after washing. The difference is theoretically the mass of contaminants that you have removed. 

When the decontamination device is ready for testing, the same quantification method will be used. First, a standard weight of plastic will be contaminated with varying levels of waste. Then, samples will be shredded to the expected size and then weighed. (Samples will be weighed after shredding to eliminate any possible losses within the machine) Samples will then go through the washing cycle. The washing times will be also be varied across sets of trials.  Finally samples will be dried, and then weighed a final time. 

These tests will do several key things:

If samples are not seeing a high level (85% or more)  of contamination removal, the team will begin altering certain aspects of the washing machine, likely including the speed of the agitator, the size/positioning of the agitator, and/or the surfactant used. 

Figure 1

In Figure 1, the EPA made a pie chart displaying what makes up municipal solid waste.

Steps to Obtaining MSW:

References

EPA: Municipal Solid Waste. (2016, March 29). Retrieved from Environmental Protection Agency: https://archive.epa.gov/epawaste/nonhaz/municipal/web/html/

             A&C Plastics Inc. (n.d.). Types of plastic: Learn what is plastic made of & different types of plastic - A&C plastics. Types of Plastic | Learn What is Plastic Made Of &  Different Types of Plastic - A&C Plastics. Retrieved January 25, 2023, from     https://www.acplasticsinc.com/informationcenter/r/7-different-types-of-plastic-and-how-they-are-used