Engineering Filtration Devices

In this lesson, students are introduced to engineering as a part of the STEM cycle. Students apply their scientific knowledge of the water cycle and Earth’s interacting systems to engineer a solution that protects water quality by filtering polluted runoff.

• Florida is home to large tropical wetlands, called the Everglades. These wetlands play an important role in the water cycle and connect all of Earth’s systems. The wetlands also purify water through filtration.  
• The Everglades have faced many environmental threats— anything that can cause harm to the environment. Pollution is a serious environmental threat facing the Everglades. 
• As rain falls, some of the water is absorbed into the ground. Whatever doesn’t absorb into the ground or get used by plants and animals can become stormwater runoff. This runoff carries with it sediment from the ground, as well bacteria, fertilizers, pesticides, oil, and other contaminants. 
• Filtration is the process of separating solid matter from a fluid by having the fluid pass through the pores of another substance, called a filter. As water moves from Earth’s surface through the Everglades, it is filtered, becoming purer.
• Engineers use scientific knowledge to design technologies that solve problems. Engineers can design solutions that help to solve the problem of water filtration, such as with storm-drain filters that filter pollutants out of water before they reach the Everglades. 
  
  

• How do wetlands such as the Everglades connect Earth’s systems?
• How are the Everglades part of the water cycle?
• Given what you know about the water cycle and hurricanes, why are hurricanes common in the Everglades region?
• How can water in the Everglades become polluted? Why, given that the Everglades can filter water, is water pollution still a threat?
• How do the Everglades filter water?
• How can engineers use nature to come up with technologies that can help solve the problem of water pollution?
• What scientific knowledge can help engineers design a filtration technology?
• How did your proposed solution of a filtration device address the problem of water pollution flowing into Monterey Bay?
• What challenges did you face in designing the filtration device prototypes?
  
  

Misconception: Science and engineering are completely separate from each other.

Fact: Science and engineering are connected. Engineers use knowledge gained from scientists to design technologies that solve problems. Scientists can then use those technologies to ask deeper questions.

Climate : the average weather over a span of 30 years

Conservation :  the weighing of human needs against the needs of the environment to create a sustainable way for humans to live off of natural resources

Engineer :  a person who uses scientific knowledge and mathematics to solve a problem by creating new technologies

Environmental Threat :  anything that can cause harm to the environment (e.g., pollution, deforestation, invasive species, overhunting, and climate change)

Filtration :  the process of separating solid matter from a fluid by having the fluid pass through the pores of another substance, called a filter

Runoff :  occurs when water, along with the substances carried in it, flow from the surface of an area of land, a building or structure

Water Cycle :  the circulation of water through the hydrosphere from Earth’s surface to the atmosphere and back

Weather :  the conditions of the atmosphere (temperature, humidity, wind speed, air pressure, and precipitation) in a particular place at a particular time

Part of the Water Cycle

There are two seasons in the Everglades: a dry season and a wet season. The dry season lasts from December to April. The wet season lasts from May to November. During the wet season, the Everglades become a river that is shallow but miles wide. It moves so slowly that it is almost impossible to see. Life in the Everglades depends on this natural cycling of water.

The wetlands play another important role in the water cycle. They improve water quality because they act as natural filters. Filtration is the process of separating solid matter from a fluid by having the fluid pass through the pores of another substance, called a filter.

The Everglades act like a strainer. As water moves from Earth’s surface through the Everglades, it is filtered, becoming purer. For example, some plants in the Everglades take pollutants into their roots and change them into less harmful substances. By the time water has moved through the Everglades, many pollutants have been removed.

Environmental Threats

But the Everglades face many different environmental threats. An environmental threat is anything that can cause harm to the environment. For example, scientists realized that human activity was causing so many pollutants to enter into the water that the Everglades couldn’t filter them all out.

This goes back to the water cycle. As rain falls, some of the water is absorbed into the ground. Whatever doesn’t absorb into the ground or get used by plants and animals can become stormwater runoff. Runoff happens when water, along with the substances carried in it, flows from the surface of an area of land, a building or structure. This runoff carries with it sediment from the ground, as well as bacteria, fertilizers, pesticides, oil, and other contaminants.

In recent years, scientists have focused on conserving the Everglades. Conservation is the weighing of human needs against the needs of the environment to create a sustainable way for humans to live off of natural resources. Conservation comes in many forms. In the Everglades, it has included setting aside some of the land as a national park and cleaning up polluted rivers.

Engineers Solve Problems

Teams of conservation scientists and engineers are working on the problem of water pollution in the Everglades. Engineering is different from science, although science and engineering are connected. Scientists use experiments to gain knowledge. Engineers use that scientific knowledge and mathematics to solve problems by creating new technologies. A technology is anything made by engineers to solve a problem. Technologies fulfill human needs or wants. Similar to how scientists follow a scientific process to answer a question, engineers also follow a process. Engineers often follow a process with eight steps that guides them as they create technologies.

The engineering process begins with a problem. In the Everglades, one problem was water pollution that harmed the surrounding environment. When engineers are defining a problem, they include the criteria. The criteria are the needs the solution must meet. They also include the constraints. Constraints are ways the solution is limited. Materials and cost are two common engineering constraints.

Once they have identified the problem, engineers need to research it to find out what is known about the problem. For example, engineers researched where the main sources of pollution in the Everglades were coming from. They realized that much of the pollution came from fertilizers used by farmers and polluted stormwater runoff.

They also researched the filtration benefits of the Everglades. For example, engineers need to know that porous materials allow water to flow through them easily. They also need to know that some materials filter water better than other materials.

After engineers have researched their problem, they survey the available materials. This survey includes a sketch of the material, as well as how much of the material they have available and the properties of that material. For example, engineers need to think about the porosity of the materials they are planning to use. The smaller the pore size is, the purer the water will be that flows through it because everything that cannot fit through the pores will be filtered out.

Engineers then come up with possible solutions for how the problem can be solved with the available materials. For example, many communities use filters made of sand, gravel, soil, or other porous material around storm drains to treat stormwater runoff. As runoff water enters the storm drain, the filter can strain out pollutants before they enter the storm drain. This solution helps to prevent pollution from becoming part of the water cycle.

Engineers then diagram and build a prototype. A prototype is a scaled- down first draft of a technology. Once built, engineers test the prototype. They use the tests to gather data, which are measurements and observations that capture how well the prototype solves the problem during testing.

Engineers who want to know how well their prototype filter works test it to see how many pollutants it filters out before the water reaches a body of water like the Everglades.

Finally, engineers use their data to decide whether to refine or replicate their prototype. The data tell engineers how well their prototype technology solved the problem.

In this lesson, students design a solution to a problem by engineering filtration devices to filter polluted stormwater runoff before it reaches Monterey Bay. Students work in groups to enigneer a possible solution for a low-cost stormwater filtration device and then test their prototypes. They then use the data and observations from their prototypes to figure out and describe how their modifications positively or negatively affected their prototype’s ability to filter out pollutants at a low cost, explain how well their prototype solved the problem, and decide if they would refine or replicate any of their designs based on the data.