While industrial facilities can have a very positive impact on the communities and economies where they are located, they can also create some risks for the people and ecosystems that are near them. In the past, I’ve written about the importance of creating buffer zones around industrial sites (Aug. 22, 2020, see article link below). This week, my focus is on the benefits of constructed wetlands just outside the boundary of a plant.
In addition to separating people from industrial operations, wetlands cleanse the effluent from fugitive emissions of hydrocarbons, heavy metals, and other contaminants. They also serve as a vital barrier in slowing flood waters and storm surge during adverse weather events. This aspect is of particular importance in heavily industrialized U.S. coastal regions, such as those around or near the Gulf of Mexico.
WETLANDS CLEAN UP SOME OF OUR MESSES
According to the USDA-NRCS Handbook for Constructed Wetlands (Davis, 1995) constructed wetlands are an excellent (and cost-effective) option for treating runoff water. In fact, they are typically less costly to build, operate, energize, and maintain than conventional waste treatment plants. They require only occasional maintenance and are tolerant of significant flow rate fluctuations. Furthermore, constructed wetlands offer scenic and aesthetic value and provide crucial habitat for wildlife.
Specific to treating potential effluent from an industrial facility, in a controlled laboratory test, vertical constructed wetlands were found to be very effective at cleaning water contaminated with diesel fuel (Al-Isawi, Sani, Almuktar, & Scholz, 2015). Mustapha, et al, (2018) found that constructed wetlands in Africa removed 45% to 99% of total hydrocarbons, including nearly all phenolic components, contained in runoff, and 70% to 80% of oil and grease.
In addition to hydrocarbon contaminants, wetlands remove heavy-metal contaminants, including copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), cadmium (Cd) and chromium (Cr), that are released into the environment through gaseous and liquid emissions from petrochemical facilities (Sun, Zhang, Cao, Xu, & Xu, 2019). The effectiveness of that removal depends upon several factors, including the plant species that are present and the duration of the residence time (Schück, & Greger, 2020).
WETLANDS PROTECT WHEN WEATHER GETS UGLY
By dampening storm surge during hurricanes and other severe coastal weather events, coastal wetlands serve to reduce storm-related damage (Sun and Carson, 2020). In that 2020 study, Sun and Carson evaluated the degree to which the presence of wetlands reduced damage in the U.S. in 2016, based on dollars per square kilometer. According to this research, in Texas, the annual marginal value of a square kilometer of wetlands ranged from a low of $6,000 in Kenedy County, to a high of nearly $6 million in Harris County (with an average in the state of $762,000 and a median of $134,000 per square kilometer). In Louisiana, the annual average value was reported to be $148,000 per square kilometer, with a median value of $56,000.
The wide disparity between the reported average and median numbers is attributable to the skewing impact of highly developed and densely populated counties such as Harris, Nueces, and Galveston Counties, in Texas, and Orleans Parish in Louisiana. Given the long-term presence of wetlands, it’s more accurate to evaluate the value they provide over a 30- or 100-year period to capture their entire life-cycle benefits. Sun and Carson (2020) estimate that the present value of wetlands increase by a factor of about 20 over a 30-year period and a factor of about 33 over a 100-year period. To put that in perspective, over a 30-year period in Harris County, Texas, wetlands provide $62,000 of avoided damage per acre.
CONSIDERING THE WIN-WIN VALUE PROPOSITION
Industrial facilities naturally attract people because such operations drive significant economic activity. However, the health, social, and environmental consequences can be dire when people get too close to those sites. Buffer zones serve to mitigate the risks.
Wetlands, when constructed in buffer-zone areas, reduce a plant’s environmental impact in two very important ways. They clean up effluent and protect the facility and surrounding environment from flooding and storm surge during hurricanes and other severe weather disasters. That’s definitely a win for all involved.TRR
REFERENCES
Al-Isawi, R H K, Sani, A, Almuktar, S A A A N, & Scholz, M. (2015). “Vertical-flow constructed wetlands treating domestic wastewater contaminated by hydrocarbons.” Water Science and Technology, 71(6), 938-946.
Davis, Luise. (1995). A Handbook of Constructed Wetlands, Vols. 1-5. U.S. Dept. of Agriculture Natural Resources Conservation Service. U.S. Government Printing Office (GPO), Washington, DC. ISBN 0-16-052999-9.
Mustapha, Hassana Ibrahim, Van Bruggen, Hans Johan Jacobus Albert, & Lens, Piet N L. (2018). “Vertical subsurface flow constructed wetlands for the removal of petroleum contaminants from secondary refinery effluent at the Kaduna refining plant (Kaduna, Nigeria).” Environmental Science and Pollution Research International, 25(30), 30451-30462.
Schück, Maria, & Greger, Maria. (2020). “Screening the Capacity of 34 Wetland Plant Species to Remove Heavy Metals from Water.” International Journal of Environmental Research and Public Health, 17(13), 4623.
Sun, Caiyun, Zhang, Zhenxing, Cao, Hainan, Xu, Miao, & Xu, Liang. (2019). “Concentrations, speciation, and ecological risk of heavy metals in the sediment of the Songhua River in an urban area with petrochemical industries.” Chemosphere (Oxford), 219, 538-545.
Sun, Fanglin, & Carson, Richard T. (2020). “Coastal wetlands reduce property damage during tropical cyclones.” Proceedings of the National Academy of Sciences – PNAS, 117(11), 5719-5725.
ABOUT THE AUTHOR
Drew Troyer has over 30 years of experience in the RAM arena. Currently a Principal with T.A. Cook Consultants, he was a Co-founder and former CEO of Noria Corporation. A trusted advisor to a global blue chip client base, this industry veteran has authored or co-authored more than 300 books, chapters, course books, articles, and technical papers and is popular keynote and technical speaker at conferences around the world. Drew is a Certified Reliability Engineer (CRE), Certified Maintenance & Reliability Professional (CMRP), holds B.S. and M.B.A. degrees. Drew, who also earned a Master’s degree in Environmental Sustainability from Harvard University, is very passionate about sustainable manufacturing. Contact him at 512-800-6031, or email [email protected].
Tags: reliability, availability, maintenance, RAM, environmental sustainability, compatible use buffers, sustainable manufacturing, energy efficiency, safety, climate change
