Sieve Determination

To filter out large sections of plastic from microplastics, we are going to sieve out the larger sections so it will not interfere with our microplastic removal methods. We have reached out to Dr. Shi about what he recommends for sieve sizes, and he informed us that we have all sieve sizes and to check in with Enyonam Ahadzi to access them.

Testing of Sieve Sizes

To determine which size sieve we need, our group tested the following sizes with our current chopped up plastic that was generated from five water bottles:

• Type 2.5 mesh (8 mm)

• Type 9 mesh (2 mm)

• Type 20 mesh (0.841 mm)

We ran the plastic through the mesh to a point where there was little plastic above 5 millimeters going through the sieve. After numerous tests, our team determined that a  mixture of a type 2.5 and type 9 mesh will filter out most of the larger plastics and let mostly microplastics through. The type 2.5 mesh will filter out pieces of plastic that are significantly larger than microplastics and the type 9 mesh will filter out plastic that is close in size to microplastics. 

We intend on implementing this sieve inside of our washer design and get the larger plastics out of the system prior to coming into contact with the ferrofluid. More research will be conducted during this step as well.

Acknowledgment and Concerns

While the sieve will manage to filter the larger plastics out, we will need to make sure that there is no way around the filter for plastic to sneak in. In addition, precautions will need to be taken to avoid an abundance of plastic from clogging the sieve and cause it to not work properly. 

There is not a 100% guarantee that the sieve will filter every plastic that is not a microplastic. Due to the nature of the shredder creating mostly thin, skinny strips of plastic, there is a realistic possibility that a strip could find its way through the sieve if oriented the proper way.