Researchers Addressing Algal Blooms in Conventional Water Treatment Facilities

Researchers Addressing Algal Blooms in Conventional Water Treatment Facilities

Powder activated carbon developed by KIST researchers. (Photo courtesy of Korea Institute of Science and Technology)

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Toxins from harmful algal blooms are increasingly contaminating sources waters, as well as the drinking water treatment facilities that the source waters supply, according to the U.S. Environmental Protection Agency. These treatment facilities face a difficult task of not only removing the toxins, but doing so in a safe and cost-effective way.

Algal blooms lately have been raising concerns due to the increased frequency of occurrence resulting from abnormally high temperatures and decreases in precipitation caused by climate change. Certain species of blue-green algae produce substances that have an earthy or moldy taste and odor, and others that are toxic. Since these substances cannot be easily removed by general water purification processes, additional treatment using advanced water purification facilities is essential.

A research team working under Dr. Kyung-Guen Song of the Water Cycle Research Center has developed a purification process for the treatment of taste- and odor-causing substances and toxins produced by blue-green algae that can be deployed in existing conventional drinking water treatment plants.

In order to deal with algal blooms, large-scale water treatment plants contain advanced water treatment equipment that uses ozone and granular activated carbon, but in the case of conventional treatment plants without such advanced water treatment equipment, powdered activated carbon is added to adsorb algal micropollutants and chlorine treatment increases the oxidizing strength.

However, in the case of conventional powdered activated carbon, it is difficult to ensure sufficient contact time due to the slow adsorption of the algal micropollutants, thus requiring an injection of large amounts of powdered activated carbon to get the job done.

Song’s team developed powdered activated carbon with an improved adsorption rate to better control algal blooms in conventional water treatment plants. The research team first pulverized powdered activated carbon to decrease the particle size. The powdered activated carbon with reduced particle size was found to have a large number of fine pores on the surface, resulting in a larger area for adsorption of algal micropollutants.

It was confirmed that the taste- and odor-causing substances and toxic substances produced by algae were adsorbed considerably faster (20% to 150% increase depending on the substance) compared to the conventional powdered activated carbon.

“Not only can the new powdered activated carbon be manufactured using quite a simple method, but it also has a fast adsorption rate, so it seems it will be possible to control algal blooms without the need to install expensive equipment in existing conventional drinking water treatment plants where it is difficult to ensure sufficient contact time,” says Song. “Once this water treatment technology is disseminated widely, it will greatly help alleviate people’s anxiety about drinking tap water.”



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