Wetlands for bioremediation have been shown to be effective for many contaminants.  The Center has the expertise in constructed / engineered wetlands to assist you in deciding whether or not an  wetland biotreatment / bioremediation system will meet your wastewater biotreatment requirements.   Once the determination has been made that an engineered wetland can be effectively used for biotreatment / bioremediation of your wastewaters, the Center can implement wetland technology in a configuration to maximize  wetland effectiveness at your site.

Interest in wetlands has increased over the last two decades.  Wetlands use natural physical, biological, and chemical aquatic processes for the biotreatment / bioremediation of polluted waters.   Wetland interest has been driven by:

• Growing recognition of restorative and purification (bioremediation) functions performed by wetland environments

• Increasingly stringent wastewater discharge criteria

• The need to develop cost-effective biotechniques / bioremediations to replace / supplement increasingly costly conventional wastewater treatments

• The potential to restore and enhance scarce wetland habitats

• The need to reclaim and reuse finite water supplies

Constructed wetlands mimic natural environments, but are ecosystem components arranged into systems selected to meet bioremediation performance goals of contaminant removal and water and nutrient reuse.  Though wetland or bioremediation design simplicity is desirable, increased complexity generally increases the range and type of treatments possible. Engineering a wetland system permits the selection and arrangement of components in a manner not occurring in nature for specific biotreatment / bioremediation purposes. Therefore, the engineered wetland system, though based on naturally occurring ecosystems, may be enhanced to achieve multiple functions such as recreational use, wildlife habitat, and wastewater management. An engineered wetland ecosystem for effective biotreatment / bioremediation of metal contaminated waters must; 1) remove metals from the water by precipitation, reduction, or oxidation; 2) in the case of acid drainage, raise the pH; and 3) accomplish these goals in a manner that does not create a toxic environment for the wetland and downstream ecosystem communities and wildlife.

Aerobic or oxidizing wetland environments promote mixed oxidation and hydrolysis reactions and are most effective when the raw water is net alkaline. Oxidizing wetlands remove iron, aluminum, zinc, and manganese as oxides, produce acid, and consist of large-surface shallow pools containing slow moving water that can be pretreated with falls or riffles to improve oxygen entrapment. Anoxic or reducing wetlands promote anaerobic bacterial activities that cause precipitation of elemental metals and metal sulfides. For acid drainage waters, necessary pH increases are usually accomplished through limestone trenches, pits, or diversion wells. A better understanding of wetland biogeochemical processes, including the diverse plant, algal, and bacterial components and their interactions is needed to 1) achieve a non-impacting (successful) metal-removal wetland system and 2) allow wetland system transferability to diverse environments.

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