We all create wastewater. Every time we brush our teeth, wash dishes, do laundry, bathe, and flush the toilet, used water flows from our homes through a vast network of pipes to a treatment plant where the water is cleaned and released back into the environment. Wastewater is generated from churches, schools, hospitals, businesses, and public buildings. You get the picture; an enormous amount of wastewater is constantly being created. Treating all this dirty water, 24 hours a day, seven days a week is an expensive, energy-intensive process, but a process that must continue uninterrupted to sustain a healthy community and environment.
But what if energy could be generated during the treatment process – clean, renewable energy that could be captured and used to dramatically reduce costs? This is the basic idea behind a winning science fair project that has earned a pair of Chantilly High School students a trip to the Fairfax County Regional Science and Engineering Fair. Working in the laboratory at Fairfax County’s Noman M. Cole Jr., Pollution Control Plant, juniors Joey Clement and Chloe Ramich conducted a month of tests on a homemade microbial fuel cell, essentially an organic battery in which electrochemically active bacteria generate a tiny amount of power as they digest sewage.
Clement and Ramich are former Sewer Science participants, a hands-on laboratory program in which high school students learn about municipal wastewater treatment from Fairfax County Wastewater Management employees. The Sewer Science program stimulated their interest in wastewater treatment and led them to compete in the science fair the past three years. They earned first place honors at last year’s regional fair for their entry “Effect of Bacteria Type on Electrical Output.” As a freshman Clement read an article about how scientists were using bacteria to generate power in bioreactors. “I thought that was cool and looked into it a little bit more,” he said. “I ended up really liking it, and I haven’t stopped yet.”
Chantilly High School Science Department Chair Karen Malloy says the school has sponsored a science fair for more than 30 years. Approximately 500 students participated in the fair last month, which is governed by the Intel International Science and Engineering Fair, the largest international pre-college science competition in the world. “Many of our science fair winners go on to pursue scientific careers. We have some graduates who are completing PhDs in bioinformatics, biology, chemistry, and other fields,” Malloy said.
To reach the International Fair, students must first advance past regionals and state. Malloy says students receive lots of support from the school. “Faculty members help guide the research and ask questions to refine student ideas and help them generate the best project that they can,” she said. In the past five years, Chantilly High School has had a dozen grand prize nominees and six grand prize winners that were awarded the option to compete at the International Fair. Malloy said she is looking forward to a good showing by Clement and Ramich at this year’s regional fair, March 11-13 at Robinson Secondary School.
Clement credits Malloy for suggesting he contact the wastewater treatment plant about using their lab. “The plant lab blows the school lab out of the water,” he explained. “We have some equipment, but the kind of resources at the wastewater plant are incredible.”
This year’s project built upon the research the team conducted for their previous fair entries. Based on the fact that electrochemically active bacteria (EAB) and non-EAB found in wastewater sludge can work together to generate power, the team looked at the effect of a mediator on the power output of a mixed-culture fuel cell. Clement found instructions online on how to construct a microbial fuel cell. “I played around with the procedure a bit and eventually came up with my cells,” he said. He built the fuel cells with components available in hardware and kitchen supply stores. The lab provided the dirty water – small amounts of returning activated sludge (oxygenated biological matter) and primary effluent (wastewater after heavy solids have settled out and oil, grease, and lighter solids are skimmed off).
One thing the students discovered was that as they increased their mediator, Methylene blue, the power output increased; however, then the chemical became toxic to the bacteria. “This was news to me,” exclaimed Clement. “Finding out the point at which the increased output is outweighed by toxicity is something we’ll have to do.”
Juan Reyes is the environmental monitoring and pretreatment branch chief for Fairfax County’s wastewater program. He oversaw the students’ project, which he described as timely and forward thinking, saying, “You can’t manage water resources and wastewater without energy, and finding innovative ways to reduce our energy usage while looking for alternative sources and ways to generate new energy are at the forefront of the challenges facing the wastewater industry today and in the foreseeable future.”
Reyes’ experience includes leading the federal government’s environmental and public health responses to natural disasters and responding to industrial accidents in Europe and Asia. He provided some statistics to illustrate what he calls the energy-water nexus, or the relationship between how much water is used to generate and transmit energy and how much energy it takes to collect, clean, move, store, and dispose of water.
- The U.S. Department of Energy says energy use can account for as much as 10 percent of a local government’s annual operating budget. With pumps, motors, and other equipment operating around the clock, wastewater facilities are among the largest consumers of energy in a community.
- According to the River Network, electricity consumption by the water and wastewater sectors is projected to rise 33 percent in the next 20 years.
- The Water Environment Research Foundation says the energy potential contained in wastewater (biosolids and biogasses) is more than 10 times the energy used to treat it, and that collectively, wastewater treatment plants could potentially meet 10 percent of the nation’s electricity demand.
- Electricity consumed for water-related purposes accounts for 13 percent of the nation’s electricity use. (the River Network)
- Nationally, the energy used by water and wastewater utilities accounts for 35 percent of typical U.S. municipal energy budgets (NYSERDA, 2008)
- Electricity use accounts for 25-40 percent of the operating budgets for wastewater utilities (NYSERDA, 2008)
Reyes says, “This represents a tremendous opportunity for the wastewater industry to not only reduce our carbon footprint and energy usage, but to also harness the considerable energy potential contained in wastewater.”
Clement says microbial fuel cell technology is in its infancy. “With some research and development, these sorts of things could be installed in wastewater treatment plants. If we figured out how to boost output by a whole lot, they could be installed for home use,” he said. If he had more time, Clement says he would do more trials, change more variables, make bigger cells, and connect cells in a series circuit. “There’s so much I wish I had time to do. The good news is I have next year!”
This enthusiasm for science is what Reyes wants to encourage at the lab. “We see our community outreach and support to students, with an interest in science, as an obligation to the residents of the county,” he said. The lab is a busy place, but Reyes says multi-use does not disrupt the lab’s main mission of environmental monitoring. Sam Farag, an environmental technologist and the students’ immediate supervisor, says that in addition to monitoring the plant’s treatment process, the lab tests storm water and USGS samples. Farag said more than 250 parameters are analyzed, such as metals, volatile and semi-volatile organics, nutrients, phosphorus, and biochemical oxygen demand. Farag, his colleague Christine Smith, and outreach coordinator Judy Fincham provided guidance to the students, as well as suitable space in which to work, and chemicals and primary effluent needed for the test.
The Sewer Science program is helping move students past the “Ewwww! factor” of wastewater treatment. By definition, wastewater is dirty. How dirty? One milliliter, or almost a quarter teaspoon, can contain up to one million microorganisms. Some of these microscopic critters, such as saprophytic bacteria, help break down organic matter in sewage. However, swimming among friendly bugs are viruses and bacteria that can carry diseases that make humans sick. That is why laws and regulations require municipalities to clean wastewater before releasing it back into the environment. Clement says his friends and family laugh when he tells them he “plays with poop.” Luckily, it takes a lot to gross him out. “The only things that makes me gag are trash and vomit,” he says.
Reyes explains that the lab is publicly owned and is staffed by expert technicians who can maintain safety and oversight requirements. “While we cannot support every science project, we have the capacity to support a limited number, especially those related to the wastewater management field,” he said. “We can and are willing to support this activity to enhance the educational experience of our constituency and build career interest in the sciences,” he adds. In addition to working with high school students, the lab is exploring new opportunities for undergraduate students from George Mason University to gain real-world experience in the environmental monitoring field. Of the experience Clement said, “I loved it. I would recommend this to anybody.”
Reyes says cleaning the nation’s water will be one of the most important challenges for public health and environmental protection in the years to come as our population and environmental demands grow. “We need to stimulate interest in the next generation of scientists to help our society with this challenge if we want to sustain our standard of living and quality of life,” he said. “Joey and Chloe’s project is very much in line with the kind of research and technology we need to be exploring,” he continued. “Who knows? Maybe our support eventually encourages one of them to develop a PhD dissertation one day that helps us meet these challenges.”
Matthew Kaiser is the information officer for Fairfax County’s Department of Public Works and Environmental Services. He values clean water and is amazed every time he turns on the tap. In his free time he enjoys skipping stones with his sons and kayaking in Gunston Cove, just downstream from his local wastewater treatment plant.