By Alina Kopnina and Olga Zavodskaya
Student research in Russia funded by the Alcoa Foundation Advancing Sustainability Research program has found a new use for a plant called myriad-leaf: industrial pollution cleanup.
Myriad-leaf (myriophyllum verticillatum) is an aquatic plant that grows in stagnant or low-flowing water, and shows great promise as a pollution-cleaner, or water “phytocleaner.” Phytoremediation – pollution cleanup with plants – has the advantage of being natural and relatively low-cost. However, the possibilities of phytoremediation are just beginning to be understood.
Myriad-leaf is common throughout central Russia, and is effective in addressing river sewage and phosphate pollutants responsible for rapid algae blooms. In areas where industrial effluent is poorly treated, heavy-metal ions build up in living organisms and are transferred throughout the food chain. In Russia and other countries with industrial water pollution, it is a challenge to remove ions from water in a cost-effective and ecologically sensitive manner.
Research coordinated by the Fund for Sustainable Development in Moscow, Water Problems Institute at the Russian Academy of Sciences and the Education Center of Ecology and Safety (Samara) addressed the effectiveness of this plant species in extracting various contaminants, including ions and unwanted biological elements, from water contaminated with petroleum derivatives.
Students from the Chemical Technology and Industrial Ecology Department at Samara State Technical University in Russia, led by associate professor Alina Kopnina and post-graduate student Olga Zavodskaya, conducted a number of experiments aimed at exploring the capability of myriad-leaf. Biological cleaning of polluted water generally utilizes air oxygen aeration, and their experiments examined the impact that adding myriad-leaf to the polluted water sample had on cleaning efficiency. Key findings included:
- Myriad-leaf is effective in treating benzyl and ethanol, two common industrial pollutants. Adding myriad-leaf to aeration cleaning techniques for benzyl solution improved cleaning efficiency by 4-13 percent, raising the cleaning efficiency to as much as 97 percent. Aerating an ethanol solution and having it flow through a mass of myriad-leaf increased cleaning efficiency from 52-89 percent.
- Iron can be recovered from polluted water with 70-75 percent efficiency using myriad-leaf, and the more plant mass that is used, the greater the efficiency. However, it should be noted that after repeated use, myriad-leaf’s effectiveness in absorbing iron decreases. Plant-based cleaning was optimal using 2-5 g of plant mass for a solution containing 1 -10 mg of iron ion per cubic decimeter.
- Myriad-leaf can help clean up hexavalent chromium contamination. After 18 hours of contact between the plant and the contaminant solution, cleaning efficiency begins to increase rapidly, reaching around 50 percent by 22 hours and reaching a maximum efficiency in approximately 72 hours. Hexavalent chromium has anti-corrosion properties and is used in stainless steel manufacture, textile dyes, wood preservation and leather tanning, among other uses. Myriad-leaf cleaning efficiency of chromium ions was approximately the same.
- Microorganisms that live on myriad-leaf also absorb pollutants, but not as efficiently as the plant itself.
Environmental challenges around drinking water and algae blooms can also be addressed using myriad-leaf. Research tested the plant’s application to sulfate ions, a common component of poorly treated industrial effluent. According to the World Health Organization, sulfate contamination in drinking water can cause adverse human health effects such as diarrhea. Student research applying myriad-leaf to aluminum sulfate-contaminated water found that a concentration of 300 mg/l of myriad leaf to 600 mg/l of sulfate ions achieved the most optimal level of cleaning. Myriad-leaf also has potential to remove phosphate ions from water to help prevent unwanted algae growth. The optimal time of contact between myriad-leaf and the test phosphate solution was 6-6.5 hours, with cleaning efficiency reaching 56 percent.
This research has yielded more than 10 published papers and several lectures and seminars on new possibilities in phytoremediation. Biological water treatment facilities using myriad-leaf may be in the future for Russia, and other areas of the world with these types of pollution challenges as well.