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| Courtesy, Ray Hull Human waste, from left, cow manure and food waste produce biogas next to a controlled environment in a science experiment led by California teens. The students found that food waste produced gas at the fastest rate. |
In May, three eighth-grade honors students from Santiago Charter Middle School in California completed a 21-day study of biogas generated from steer manure, human biosolids and food waste.
The experiment not only had a high gross factor, it earned the 14-year-old young researchers serious science credentials and a first place in the school's first science fair.
Courtesy, Ray Hull From left, Charlie Hull, Bradley Warren and Justin Spitzer show off the blue ribbons they received for their project, “Biomass to Biogas,” in the Santiago Charter Middle School science fair. Charlie’s father, Ray Hull, is business manager for Central Region Landfills in Orange County, Calif."If we change the type of biomass [steer manure, human biosolids and food waste], then we will produce different amounts of biogas," the students said in their report. "Also, we predict food waste will produce the most biogas of the three biomasses."
Bingo!
The trio had measurable success with the experiment facilitated by Charlie's dad, Ray Hull, the business manager for Central Region Landfills, who helped them obtain their raw materials. They collected human biosolids liquid from the Orange County Sanitation District, food-waste slurry from Waste Management Inc. and fresh steer feces from Orange High School's stables.
"We went to [sciencebuddies.org] for ideas about experiments and we chose this because it had the 'ick' factor and involved renewable energy," Charlie said.
From there they donned protective clothing – a hazmat suit, particulate respirator mask, protective face shield and latex gloves – and put the materials into separate plastic bottles. Then they filled the bottles with distilled water to make them anaerobic and covered the mouth of each soda bottle with a rubber balloon to capture any biogas produced.
For the next 21 days, the boys visited the Hull laboratory – aka Charlie's garage – and measured the circumference of balloons in centimeters.
The results: Biogas from human biosolids filled three balloons to an average circumference of 9.16 centimeters. Cow manure filled three balloons to an average circumference of 8.45 centimeters. Food waste filled three balloons to an average circumference of 17.8 centimeters.
The interesting part, Charlie said, was that the steer manure and biosolids began producing biogas in a few days. The food waste sucked the balloons inside the bottle necks.
"On Day 17 and Day 18, the food waste balloons ripped," he said. The boys replaced the balloons and the food waste began generating biogas just two days later and in the end, generated the most biogas of the three biomasses.
The scientific conclusion: All three biomasses generated biogas, but that manure and biosolids generated biogas in an anaerobic environment, while food waste preferred an aerobic environment.
The academic conclusion: A+.
Led by teachers Kim Meier and Dorothy Yan, the biomass project was one of more than 100 science fair projects implementing the scientific method involving a hypothesis, independent and dependent variables, collecting data and presenting it graphically and formulating conclusions about results.
Each team had to give an oral presentation and create visual displays of its scientific findings. Projects were reviewed by more than 35 judges, including veteran scientists, area business professionals and educators.
"The hardest part was all the research ... and the materials were kind of nasty," said Bradley. "There weren't really any surprises; our hypothesis was supported by the data."
