The Bark Camp Run demonstration constructed wetlands: Findings and recommendations for future design criteria
- PA Dept. of Environmental Protection, Hawk Run, PA (United States)
The performance of six wetlands built to ameliorate acid mine drainage has been analyzed over 806 days. The wetlands are each 52 m x 8 m at the water surface, with a 5 cm surface water column and 60 cm depth of substrate consisting of horse manure mixed with an equal volume of SiO{sub 2} stone. Each wetland has a 1 mm polyethylene liner and wooden deflectors ever 2 m to promote uniform flow. The dominant macrophyte is Typha latifolia. Flows are {approximately}10 m{sup 3}/d. Tracer studies showed that the mine drainage flows through both the surface water column and the substrate, and a one-dimensional flow model appears satisfactorily to explain the performance of the wetlands. Wetlands should be designed to achieve uniform flow and to maintain flow through the substrate A polishing area of a few m{sup 2} with a substrate consisting only of limestone chips appears to be helpful in maintaining effluent alkalinity. Simple mathematical models were developed to assess the performance of the constructed wetlands. Removal of Fe{sup +3} is by hydrolysis, followed by reduction to Fe{sup 2+} and incorporation into the substrate. Removal of Al{sup +3} is by hydrolysis. The observed removal rates of 1g d{sup -1} m{sup -2} for Fe{sup +3} and 0.5g d{sup -1} m{sup -2} for Al{sup +3}, combine with concurrent neutralization of the resulting H{sup +}, to give an acidity removal rate of 5.5g d{sup -1} m{sup -2}. A zero-order rate law can be used to describe the observed rate of Fe{sup +3} removal First-order rate laws also produce good representations for the rates of Fe{sup +3} and Al{sup +3} removal. Effluent Mn concentration > influent [Mn], and declines in accordance with a first-order rate law, indicative of desorption of Mn{sup 2+} initially present in the substrate. This may explain past difficulties in assessing Mn removal in anaerobic constructed wetlands.
- OSTI ID:
- 588833
- Report Number(s):
- CONF-9605286-; TRN: 98:001296-0047
- Resource Relation:
- Conference: 13. annual meeting of the American Society for Surface Mining and Reclamation (ASSMR), Knoxville, TN (United States), 18-23 May 1996; Other Information: PBD: 1996; Related Information: Is Part Of Successes and failures: Applying research results to insure reclamation success; Daniels, W.L.; Burger, J.A.; Zipper, C.E. [Virginia Tech, Blacksburg, VA (United States). Depts. of Crop and Soil Environmental Sciences and Forestry] [eds.]; PB: 889 p.
- Country of Publication:
- United States
- Language:
- English
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