title: Floating treatment wetlands for domestic wastewater treatment.
abstract: Floating islands are a form of treatment wetland characterized by a mat of synthetic matrix at the water surface into which macrophytes can be planted and through which water passes. We evaluated two matrix materials for treating domestic wastewater, recycled plastic and recycled carpet fibers, for chemical oxygen demand (COD) and nitrogen removal. These materials were compared to pea gravel or open water (control). Experiments were conducted in laboratory scale columns fed with synthetic wastewater containing COD, organic and inorganic nitrogen, and mineral salts. Columns were unplanted, naturally inoculated, and operated in batch mode with continuous recirculation and aeration. COD was efficiently removed in all systems examined (>90% removal). Ammonia was efficiently removed by nitrification. Removal of total dissolved N was ∼50% by day 28, by which time most remaining nitrogen was present as NO(3)-N. Complete removal of NO(3)-N by denitrification was accomplished by dosing columns with molasses. Microbial communities of interest were visualized with denaturing gradient gel electrophoresis (DGGE) by targeting specific functional genes. Shifts in the denitrifying community were observed post-molasses addition, when nitrate levels decreased. The conditioning time for reliable nitrification was determined to be approximately three months. These results suggest that floating treatment wetlands are a viable alternative for domestic wastewater treatment.
authors: Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717, USA.
authors: J L
authors: JL
authors: Faulwetter
authors: M D
authors: MD
authors: Burr
authors: A B
authors: AB
authors: Cunningham
authors: F M
authors: FM
authors: Stewart
authors: A K
authors: AK
authors: Camper
authors: O R
authors: OR
authors: Stein
mesh_terms: D001420:Bacteria, Aerobic / Q000201:enzymology / Q000254:growth & development / Q000302:isolation & purification; D001673:Biodegradation, Environmental; D018441:Biofilms / Q000254:growth & development; D057919:Biological Oxygen Demand Analysis; D004269:DNA, Bacterial / Q000235:genetics; D058645:Denaturing Gradient Gel Electrophoresis; D009009:Montana; D009572:Nitrite Reductases / Q000235:genetics; D009584:Nitrogen / Q000302:isolation & purification*; D010088:Oxidoreductases / Q000235:genetics; D010865:Pilot Projects; D010969:Plastics / Q000737:chemistry; D016133:Polymerase Chain Reaction; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*; D060753:Water Quality / Q000592:standards; D053833:Wetlands
chemical_list: D004269:DNA, Bacterial; D010969:Plastics; D014874:Water Pollutants, Chemical; D010088:Oxidoreductases; D009572:Nitrite Reductases; C045582:ammonia monooxygenase; D009584:Nitrogen