Project Narrative

Final Ashby Chart for Chosen Material

Design Process

Week 1 (Jan. 6, 2025):

• Initial problem statement, constraints, and objectives
• Objective tree

Objective Tree

Week 2:

• Generated metrics to evaluate the objectives of the filter
• Note some of the regulations and policies engineers must adhere to regarding the location of the treatment plant (Tampakan, Philippines)
• Morphological chart to identify means to achieve the following functions:
  • Remove contaminants
  • Regulate flow
  • Regulate temperatures
  • System is cleanable

Week 3:

• Determined primary and secondary objectives
• Created an objective and MPI table
• Generated a material property chart

Week 4:

• Found three finalists for materials to be used
• Chose final material
• Applied porosity conditions on selected material
• Evaluated the sustainability of the chosen material
• Calculated a new adjusted yield strength

Week 5 (Feb. 14, 2025):

• Created a LCA of the top three materials
• Created a lifestyle inventory with the top three materials
• Created Eco-audits for the top three materials
• Discussed implications of these results

For this project, our design team focused on developing a filtration component specifically aimed at addressing the issue of algae growth, particularly toxic cyanobacteria blooms, in a wastewater treatment plant located in Tampakan, Philippines. The high temperatures and nutrient rich conditions in the plant’s ponds have led to an overgrowth of cyanobacteria, which not only hinders the treatment process but also produces harmful toxins affecting local livestock.

To solve this problem, our team following the Engineering Design Process in three stages. First, we researched existing filtration technologies and identified key design requirements. Next, we developed a conceptual design by selecting suitable materials that met these requirements and optimized mechanical performance. Finally, we created a life cycle inventory of our design and use the Eco Audit Tool in the ANSYS-Granta EduPack to evaluate the environmental impact of our filtration system throughout its lifespan.

Objectives:

• The device should be cost-efficient, meaning it must be affordable to produce and maintain, using inexpensive materials and minimizing expenses to be accessible for a wide range of users
• The device should be environmentally friendly, incorporating sustainable materials and processes that minimize ecological impact and avoid harmful byproducts
• The device should be durable, built to withstand long-term use and exposure to harsh environmental and chemical conditions without frequent repairs or degradation in performance

Constraints:

• All materials used must be non-toxic and safe for use in water treatment as to not leach harmful substances into the water
• The filtration system must fit within the existing infrastructure of the treatment plant, without requiring major structural modifications
• The material used must maintain effective performance for a minimum operational lifespan (5-10 years) without the need for full replacement

Functions:

• The system must effectively remove contaminants, including cyanobacteria from the wastewater to be sure of safe water output
• These system must regulate flow to maintain consistent filtration performance and prevent clogging or overflow
• The system should regulate temperature or remain stable under varying thermal conditions for durability in the equatorial climate
• The system must be easily cleanable, allowing for routine maintenance without complexity or special equipment

Morph Chart to Assess all Functions

Summary

Material Performance Index Calculations Using Material Performance Indices (MPIs), we quantitatively compared materials based on combinations of strength, stiffness, cost, and carbon footprint. Four specific MPIs were calculated:

1. Strength-to-Cost
2. Stiffness-to-Cost
3. Strength-to-CO2 Emissions
4. Stiffness-to-C02 Emissions

MPI Chart

These ratios helped us evaluate which materials offered the best balance between mechanical performance and sustainability. The MPIs were visualized using Ashby charts, which allowed us to identify candidate materials that fell above the performance threshold lines. Based on the analysis, the top materials were narrowed down to Polypropylene Fiber (PP), Ceramic Foams, and Polyethylene Terephthalate (PET).

While Ceramic Foam had the lowest environmental impact, it was ultimately eliminated due to its brittleness and impracticality in fiber form. Between PET and PP, Polypropylene Fiber was selected due to its lower cost, regional availability (manufactured in Indonesia), and overall compatibility with mechanical and environmental constraints.

Porosity Calculations Each fiber was modeled as a cylinder 150 mm in length and 7.25 mm in diameter, while each pore was modeled as a smaller cylinder 1 μm in radius and 7.25 mm in length. The volume of a single pore was calculated as approximately 5.69 x 10^-6 mm^3, and the volume of a single fiber was 6192.37 mm^3. With a maximum of about 1.55 x 10^8 pores per fiber, the total pore volume reached a significant fraction of the total fiber volume.

Using the equation: P = (# pores) x (Volume of single pore)/ (Volume of fiber)

The resulting porosity was approximately 0.14, or 14%, meaning about 14% of the filter volume is made up of pores for water to pass through.

Eco-Audit Analysis for Polypropylene Fiber

• Meets mechanical requirements
  • Strong and durable under 400 psi pressure
  • Effective elastic modulus remained acceptable even with porosity
• Energy and environmental considerations
  • Highest production energy (4.43e+6 MJ), but acceptable tradeoff
  • Lowest transport energy (2.25e+4 MJ) – shipped by boat from Indonesia
  • End-of-life: recyclable, but limited (~1% actual recycling rate) → 0 MJ impact
• Compared to alternatives
  • PET: better recyclability, but high transport energy (3.15e+5 MJ via air)
  • Ceramic Foam: lowest environmental impact, but fails mechanical tests

Eco-Audit for Chosen Material

Life Cycle Assessment for Chosen Material

Team’s Work and Personal Contributions

As a team:

• Collaborated with the team to select the best materials based on performance, cost, and environmental impact.
• Worked alongside team members to evaluate different filter designs and their mechanical properties, ensuring they met the required specifications.
• Assisted in the use of Material Performance Indices (MPI) and other computational tools to guide the selection of materials and assess their suitability for the project.

Individually:

• Researched and summarized relevant regulations and standards that apply to wastewater filtration systems.
• Ensured the design complied with local environmental and health regulations, particularly regarding wastewater reuse and the prevention of toxic algae blooms.
• Led discussions on sustainability, focusing on the environmental impact of materials used in the filtration system.
• Suggested potential alternatives to conventional materials, such as biodegradable options or those with a lower carbon footprint.
• Contributed to evaluating materials based on their environmental sustainability through tools like the Eco Audit Tool.

Reflection