S1 PLTW ES Final Exam Review - Unit 2

Which stage of wastewater treatment involves the use of microbes to break down organic matter remaining in the water?

• Primary treatment

• Secondary treatment

• Tertiary treatment

• Advanced treatment

Modern sewage treatment plants use multiple stages to clean water entering a treatment facility.

Making a careful observation of the photograph shown, which step in the water treatment process does this image represent?

• Settling tank

• Chlorination

• Screening

• Grit removal

Most modern sewage treatment plants are similarly constructed to achieve water purification.

Keeping in mind common sewage water contaminants, in what order is it most efficient to design the process of treating sewage water?

• Step 1: Isolation or purification or biological organisms
  Step 2: Particulate filtration and separation
  Step 3: Microbial breakdown or organic material
  Step 4: Chemical clarification or disinfection

• Step 1: Chemical clarification or disinfection
  Step 2: Isolation or purification or biological organisms
  Step 3: Particulate filtration and separation
  Step 4: Microbial breakdown or organic material

• Step 1: Particulate filtration and separation
  Step 2: Microbial breakdown of organic material
  Step 3: Isolation or purification of biological organisms
  Step 4: Chemical clarification or disinfection

• Step 1: Microbial breakdown or organic material
  Step 2: Chemical clarification or disinfection
  Step 3: Isolation or purification or biological organisms
  Step 4: Particulate filtration and separation

Students were attempting to build a water filter that would filter dirty water and make it suitable for drinking. Using the engineering design process, the students:

• worked through several ideas

• sketched and built their water filter

• tested it by passing a dirty river-water sample through it several times

After the final pass, the water looked clear.

What should the students do next?

• Drink the water; it is now potable. Serve the water to panel members while presenting results to engage them.

• Sketch and build other ideas even though the first one worked. They may find a better one. 

• Design small, compact packaging for their device so that it can be shipped to areas in need of clean water.

• Test the water for contaminants as some may be still present even though the water appears clear.

Wastewater that enters a combined sewer system contains many components that could be harmful to human health. Wastewater treatment systems ensure the removal of these contaminants so that water may be safely returned to the environment.

Several steps are involved in treating wastewater. Select yes or no to identify the items that would be removed during primary wastewater treatment.

• Hair

• Coins

• Solid Waste

• Bacteria

• Toilet Tissue

Wastewater that enters a combined sewer system contains many components that could be harmful to human health. Wastewater treatment systems ensure the removal of these contaminants so that water may be safely returned to the environment.

Which method is used to remove contaminants during primary wastewater treatment?

• Screen

• Chlorination

• Ultraviolet light

• Aerobic digestion

The wastewater treatment facility must test incoming and outgoing water to ensure that maximum contaminant levels (MCL) are not exceeded. The table shows water quality results. CFU = colony-forming units.

According to the table, would the effluent water be safe for human consumption?

• No. The fecal coliform value is not within the acceptable range. 

• No. The chlorides value is not within the acceptable range.

• Yes. The results fall within the MCL guidelines.

• Yes. The test results important for drinking water fall within the MCL guidelines.

Wastewater treatment officials are trying to educate the public about what is acceptable to send down the drain. Which method would be most effective in informing the most people?

• Mail out a lengthy document that describes everything in detail.

• Invite the public to stop by the treatment plant for an informative tour. 

• Create a video and release it to social media sites. 

• Have a booth at the county fair so that people can stop by and learn about it.

In developing countries, lack of clean water leads people to consume contaminated water. Many people become ill as a result. Water contamination can occur in developed regions as well. Sometimes infrastructure fails, resulting in an influx of contaminants into the water supply.

Everyone must work together to combat the global water crisis.

How can people in developed countries help combat the water crisis? For each behavior, select yes or no to indicate whether it helps combat the water crisis.

• Drink sea water

• Wash full loads

• Take shorter showers

• Flush the toilet before and after use

• Collect rainwater to use for watering plants

In developing countries, lack of clean water leads people to consume contaminated water. Many people become ill as a result. Water contamination can occur in developed regions as well. Sometimes infrastructure fails, resulting in an influx of contaminants into the water supply.

Everyone must work together to combat the global water crisis.

Many members of a community in rural America have experienced a variety of gastrointestinal issues that have led to dehydration. The community relies on private well water. Local scientists believe that chemical water contamination may be a factor. 

Which water contaminant is likely responsible for the community's health problems?

• Sulfates

• Nitrates

• Ammonia

• E. coli