Functional Requirements

In order to properly define our problem, an important task for the team was to find functional requirements. These functional requirements define constraints and objectives for the problem with the goal of changing an ill-defined problem to a well-defined one. To decide what those functional requirements would be, we first brainstormed as a team by writing down potential needs on sticky notes. We put them up on a whiteboard and looked for some things they had in common. After some discussion, we found 5 needs that we felt would well define the problem. These needs were then translated into measurable functional requirements. Once these functional requirements were defined, a few team members determined which would be constraints and which would be objectives, and then ranked them based on priority. These initial functional requirements then had to be adjusted once the team decided to narrow the scope of our problem to focus on how we can limit contamination from the user in single-use plastics. We came to this focus on plastics due to the number of plastic straws, plastic utensils, and contaminated plastic cups that were incorrectly recycled in an experiment we conducted with the student body.

Our main need in order for our solution to be successful is that the output is clean, contamination-free plastic. The functional requirement for this need is that there is less than 10% contamination in the recycled plastic that is collected after interaction with our solution. This value of 10% was found through our team’s interview with Scott Kennedy.

To break down this main functional requirement into smaller, more easily-measured pieces we made three functional sub-requirements that deal with things that make up contamination in recycling. These deal with the need to have recycling that is free from liquids, food, and materials other than recyclable plastics:

• The functional requirements for liquid-free recycling are that the weight of the liquid itself is less than 10% of the total weight of the bag, and that the percentage of items containing significant amounts of liquid is less than 5% of the whole bag.
• The functional requirement for food-free recycling is that the percentage of items containing significant amounts of food is less than 5% of the whole bag.
• The functional requirement for recycling with only recyclable plastic materials is that the percentage of items that are not specifically made from recyclable plastic is less than 5% of the whole bag.

These percentage and weight values were found by speaking with facilities members to see what amounts of contamination they would visually observe before considering the bag of recycling to be trash. We plan to improve our specifications by conducting interviews with more stakeholders, specifically the recycling plant used by Lafayette and more members of facilities, and recording their feedback and suggestions on how they could be improved.