Leveraging Mother Nature’s Treatment Systems
Since the earliest forms of life, microbes have effectively served as a treatment system for removing organic and inorganic pollutants from water and soil. But with advancements in technology, these natural mechanisms for water quality enhancement have been replaced by a combination of chemical, enhanced biological, and mechanical systems for storm and wastewater treatment.
While newer treatment technologies are very effective, the use of natural treatment systems can also offer a low cost, low maintenance solution with proven results that meet National Pollutant Discharge Elimination System (NPDES) standards. Here are a few examples of how these methods have been successfully applied.
If you build it, they will come
Natural wetlands perform many functions that are beneficial to humans and wildlife, including creating the right conditions for micro-organisms that can transform and remove pollutants from water. So why not construct them to help improve water quality?
Because they are self-sustaining habitats, wetlands also are well suited to handle widely fluctuating hydraulic and pollutant loads that typically cause operational problems for more traditional treatment approaches. Seasonal increases in loads at Camp Otterbein in Logan, Ohio made a constructed wetland solution the perfect choice to replace their outdated onsite treatment plant. This lower cost option not only meets compliance standards but also saves on sand filters and disinfection chemicals, while also integrating with the camp’s natural outdoor setting.
Let it rain
Bioretention areas, or rain gardens, are shallow, landscaped depressions with high organic substrate. They allow stormwater runoff to pond in a designated area, infiltrating through the organic media for filtration and contact with the naturally occurring microbes. These areas also provide additional storage for runoff and can improve the quality of the excess stormwater that overflows the unit and is discharged into streams.
The City of Columbus, Ohio installed bioretention basins in select residential areas as part of the Blueprint Columbus pilot program aimed at taking a greener approach to sanitary sewer overflows (SSOs). Stormwater runoff from private properties was entering sanitary sewers and contributing to SSOs. Now, runoff goes into the bioretention basins within the neighborhood right of way, between the curb and property boundary or sidewalk. After filtering through the top layer of permeable engineered soil and plants and a layer of gravel, it flows through an underdrain that routes it to the storm sewer.
Get to the root
Phytotechnology uses tree plantings for water management. The natural evapotranspiration process of the trees – as well as the microbial population that naturally exists within their root zones – provides another low-cost alternative for water quality improvement over traditional systems.
At the Watson Road Landfill in Newark, Ohio, 2,900 hybrid poplar and willow trees planted on the landfill cap along with selected hardwoods help reduce the levels of saturation within the subsurface and treat on-site leachate before discharge. This natural solution brought the owner into compliance with their discharge permit while reducing capital costs by about $1 million over a traditional pump and treat alternative. It also eliminates the cost to treat millions of gallons of water through the sanitary wastewater treatment facility each year.
While natural treatment systems won’t be a fit for every project, under the right conditions, they can be a low-cost, low maintenance solution to achieving permit compliance. Contact me to discuss how a natural solution might fit into your next water treatment project.