Learning Sewer Science

A comprehensive science laboratory -- the result of a joint project among three California agencies -- teaches high school students about municipal wastewater treatment

"Now I know there are people at the other end of the toilet." That's the response of one Northern California high school student after completing a unique wastewater treatment laboratory. In the San Francisco Bay area, wastewater professionals are helping high school students understand the profession and to move beyond the standard "flush and forget." The program recently received the 2001 Public Education Award from the California Water Environment Association.

"Sewer Science" is the name given to this comprehensive science laboratory that teaches students about municipal wastewater treatment using specially designed tanks and standard analytical equipment. Developed to be suitable for and flexible to the needs of grades nine through 12, the curriculum integrates chemistry, physics and microbiology and raises questions regarding personal responsibility, technology and societal issues.

Many wastewater agencies conduct pollution prevention outreach in the community to meet permit requirements. If there is a school outreach component, it is typically aimed at elementary students. Wastewater treatment agencies participating in Sewer Science have concluded that reaching out to high school students is crucial to their pollution prevention program because it provides an opportunity to discuss higher level concepts than at the elementary level.

"Students need a foundation, grounded in the basic concepts of wastewater treatment, prior to understanding why certain household chemicals should not go down their sink drain," says Phil Bobel, Environmental Compliance Manager for the city of Palo Alto, Calif. Without such a foundation, students likely assume that any household product, including heavy metals and pesticides, can be effectively treated before release to a local waterway.

Meanwhile, the wastewater field is beginning to analyze issues, such as endocrine disrupting compounds and pharmaceutically active compounds, which will require sophisticated community members to understand both the risks and the options. The goal is to foster the development of community members and future leaders through this hands-on laboratory.

Ken Kaufman, Technical Services Manager for South Bayside System Authority, adds, "The payback is when these students become well-informed members of our community and can react intelligently to water pollution issues."

The Curriculum
During the seven-day lab, students realistically simulate wastewater treatment operations:

  • primary sedimentation;
  • biological treatment followed by secondary sedimentation;
  • filtration; and
  • disinfection.

First, students create wastewater using ground up dog food and cereal, used coffee grounds, vegetable oil, ammonia, toilet paper and baking soda. The students are asked to think about what each ingredient represents in real wastewater. While most determine immediately that the toilet paper represents real toilet paper, other ingredients can stump them. Few students realize that the ammonia represents urine.

Students spend the week manipulating Plexiglas models of treatment operations, including a sedimentation tank, aeration tank and dual media filters. Each day is devoted to a different operation. As the wastewater moves from one treatment operation to another, students are asked to hypothesize about the fate of specific wastewater components. For instance, during primary treatment, which of the wastewater components will sink? Which will float? Which will dissolve? In secondary treatment, which components will be degraded by the biomass?

Students make quantitative measurements, including pH, turbidity, ammonia and chemical oxygen demand. They also learn the importance of each of these parameters to water quality. Throughout the lab, students observe improvements in the water quality. At the lab conclusion, students plot their data and compare their results to U.S. Environmental Protection Agency (EPA) effluent standards.

The biological treatment is often the favorite part of the lab unit. "Real activated sludge is added to the aeration tanks. Students are instructed about safe lab techniques so they can view and identify the sludge organisms using microscopes and identification charts," according to Kathy Suter, Laboratory Director for the South Bayside System Authority.

By the end of the weeklong curriculum, students understand that if a chemical cannot be removed using sedimentation, biological treatment or filtration, they should prevent that chemical from entering the wastewater system. According to high school teacher Maya Slocum, "Students become concerned about the impact of common household chemicals on the environment and begin questioning which products are safe."

First Day of School
The original idea for the laboratory came from a demonstrated need at Menlo-Atherton High School in Atherton, Calif. In 1998, their ninth grade science class was redesigned as an integrated science class that would introduce students to the different science disciplines and present examples of how those sciences fit together. Teacher Maya Slocum recognized that wastewater treatment is a real-life use of science and technology to solve an environmental problem. Ms. Slocum requested technical support from the city of Palo Alto's Environmental Compliance Division. Palo Alto staff jumped at the opportunity and enlisted the help of Dr. Rhea Williamson, civil engineering professor at San Jose State University. According to Dr. Williamson, "The lab is a valuable tool to integrate a variety of science concepts, such as from density to pH, from microbial cell biology to the nitrogen cycle. There are also opportunities to discuss human impacts, such as the finding of hormones in fresh water, and the limits of technology, such as the inability of domestic treatment to remove toxic metals."

Within months, the Palo Alto Regional Water Quality Control Plant (RWQCP) and San Jose State staff designed prototype model treatment units and created a wastewater recipe that had realistic water quality parameters and was treatable in the model units.

Soon, other sanitation agencies signed up, recognizing the opportunity to educate future voters and build a foundation for pollution prevention programs. The program is now a joint project between three California agencies, the city of Palo Alto, Central Contra Costa Sanitary District and South Bayside System Authority. These agencies provide the lab to high schools in their service areas and collaborate to enhance the program materials and market the program to other agencies.

One element crucial to the success of the program was the creation of a student workbook. Says Maya Slocum, "In the early days of the program, there were so many worksheets that it was difficult for students to keep track of them. The workbook streamlines the lab, laying out each treatment process and water quality test with background information and assists students in analyzing their final water quality with regard to EPA guidelines." The workbook, written by employees with the city of Palo Alto and designed by Central Contra Costa Sanitary District, contains protocols for all test methods, data tables for results, laboratory guides for each day, conclusions pages, graph paper, information about careers in water pollution control and a glossary. The cover of each workbook is modified by the wastewater agency to reflect their facility.

The three agencies are busy sharing their enthusiasm about their joint program. In 2001, the Water Environmental Federation (WEF) invited the group to attend the annual national WEFTEC Conference to market Sewer Science as a high school outreach tool for wastewater agencies. According to Harriette Heibel, Community Affairs Manager for Central Contra Costa Sanitary District, "We are eager to share this unique and teacher-friendly program with other agencies in the hope that they will take advantage of the thoughtful and thorough developmental effort that went into creating this program. We think it's a worthwhile investment in high schools."

At WEFTEC, the agency representatives discussed additional ways one could use this type of training module. For instance, a consulting firm could team with a wastewater agency to pay for equipment and materials for local schools. Agencies could also use the model treatment plant as a training module for operators, or to educate environmental groups, city council members, district board members or permitting agencies.

The goals of the Sewer Science training module include

  • Teaching students the basic concepts of primary, secondary and tertiary treatment;
  • Exposing students to analytical methods for water quality, such as chemical oxygen demand, that are otherwise prohibitively expensive for most high schools;
  • Fostering an awareness about the fate of household chemicals in the sanitary sewer;
  • Encouraging students to take responsibility for the household products that they use;
  • Providing information on careers in wastewater; and
  • Linking science and technology to environmental impacts and issues.

A Web site was recently created to assist agencies with creating a similar training module for their high schools. The Web site includes

  • A complete list of materials;
  • Specifications to build model tanks;
  • Downloadable student workbook;
  • Downloadable teacher workbook;
  • Health and safety information; and
  • A sample flyer to mail to local teachers.

Development and support funding has been provided by the city of Palo Alto, South Bayside System Authority, Central Contra Costa Sanitary District, Community Foundation of Silicon Valley and the California Department of Education.

This article originally appeared in the 05/01/2002 issue of Environmental Protection.

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