Things That Matter to Flocculants
Students collect local pond or river water and use flocculants to clean it.Copyright (left) Lawrence Livermore National Laboratory, U.S. Department of Energy and (right) 2011 Audrey Buttice, STARS—University of South Florida https://www.llnl.gov/str/October02/October50th.html
Prior to reaching households, water is exposed to a variety of treatments designed to render it fit for human consumption and use. One of the first treatment steps is the removal of suspended solids using chemical additives called flocculants. In this activity, students learn about two commonly used flocculants and clean water collected from a local pond or river. They experiment with flocculant, stirring and pH variables.
Engineers employ basic scientific principles to design flocculants that remove suspended solids from dirty water. As a result, many flocculants are commercially available and are commonly used in water treatment facilities. Ongoing research is developing new, more efficient flocculants. In addition, engineers around the world are studying the use of natural flocculants that have the potential to greatly aid developing countries by providing a method of water purification.
After this activity, students should be able to:
- Describe the effectiveness of flocculants in purifying water.
- Explain whether adding mechanical kinetic energy (stirring) helps flocculants work better, and why.
- Determine whether the type of flocculant affects how clean the water is.
- Determine whether or not the addition of lemon juice (which creates an acidic environment) affects how a flocculant works.