PHYTO-ENGINEERING APPROACHES TO CONTAMINATED DREDGED MATERIAL

摘要

The U. S. Army Corps of Engineers dredges 280 million m~3 of dredged material annually from waterways to maintain navigation. Some of the dredged material is contaminated from various discharges into waterways. Dredged material not suitable for open water disposal is normally placed in confined disposal facilities (CDFs). These facilities fill up. New CDFs are getting extremely difficult to establish. Storage space for future dredging is becoming a real problem. Consequently, the U.S. Army Corps of Engineers' Engineer Research and Development Center, Waterways Experiment Station (USACE-ERDC-WES) has been evaluating innovative technologies for reclaiming contaminated dredged material from CDFs and producing beneficial reuse products. One reclamation technology is Phyto-Engineering or the use of plants to achieve engineering objectives. Incorporated in Phyto-Engineering is other technologies such as recycled soil manufacturing technology (RSMT) that allows a fertile topsoil to be manufactured from contaminated dredged material, residual cellulose, residual biosolids and other residual waste materials. Once topsoil is manufactured from contaminated dredged material, plants can be grown to phyto-remediate contamination and phyto-reclaim the dredged material from contamination. Phyto-Stabilization uses plants to stabilize the dredged material and controls soil erosion. Phyto-Extraction of metals uses specific metal hyper-accumulator plants to extract metals from the reconditioned dredged material to clean up the dredged material for beneficial use. Phyto-Degradation of organic contaminants uses specific plants and root associated microorganisms to bio-degrade organic chemicals such as PAHs and PCBs in dredged material. These Phyto-Engineering technologies can be applied to contaminated soils as well as dredged material. Examples include application to Superfund sites, Brownfield Sites, Minelands and Landfills.