title: Glyphosate degradation by immobilized bacteria: field studies with industrial wastewater effluent.
abstract: Immobilized bacteria have been shown in the laboratory to effectively remove glyphosate from wastewater effluent discharged from an activated sludge treatment system. Bacterial consortia in lab columns maintained a 99% glyphosate-degrading activity (GDA) at a hydraulic residence time of less than 20 min. In this study, a pilot plant (capacity, 45 liters/min) was used for a field demonstration. Initially, activated sludge was enriched for microbes with GDA during a 3-week biocarrier activation period. Wastewater effluent was then spiked with glyphosate and NH4Cl and recycled through the pilot plant column during start-up. Microbes with GDA were enhanced by maintaining the pH at less than 8 and adding yeast extract (less than 10 mg/liter). Once the consortia were stabilized, the column capacity for glyphosate removal was determined in a 60-day continuous-flow study. Waste containing 50 mg of glyphosate per liter was pumped at increasing flow rates until a steady state was reached. A microbial GDA of greater than 90% was achieved at a 10-min hydraulic residence time (144 hydraulic turnovers per day). Additional studies showed that microbes with GDA were recoverable within (i) 5 days of an acid shock and (ii) 3 days after a 21-day dormancy (low-flow, low-maintenance) mode. These results suggest that full-scale use of immobilized bacteria can be a cost-effective and dependable technique for the biotreatment of industrial wastewater.
authors.affiliation: Monsanto Agricultural Company, St. Louis, Missouri 63167.
authors.forename: L E
authors.initials: LE
authors.lastname: Hallas
authors.forename: W J
authors.initials: WJ
authors.lastname: Adams
authors.forename: M A
authors.initials: MA
authors.lastname: Heitkamp
mesh_terms: D001673:Biodegradation, Environmental; D005998:Glycine / Q000031:analogs & derivatives* / Q000378:metabolism; D006540:Herbicides / Q000378:metabolism*; D012722:Sewage; D014871:Water Microbiology; D000097797:Glyphosate
chemical_list: D005998:Glycine; D006540:Herbicides; D012722:Sewage; D000097797:Glyphosate