2,4-D removal via denitrification using volatile fatty acids

• Published in: Water science and technology 2011-01, Vol.63 (1), p.178-183
• Main Authors: He, X, Wareham, D G
• Format: Article
• Language: English
• Subjects: 2,4-Dichlorophenoxyacetic Acid - isolation & purification; Acetic acid; Anaerobiosis; Bacteria; Biodegradation; Denitrification; Digesters; Fatty acids; Fatty Acids - chemistry; Herbicides; Nitrates; Nitrites - chemistry; Sewage; Volatilization
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2011.030

Many countries have waters contaminated with both herbicides and nitrates; however, information is limited with respect to removal rates for combined nitrate and herbicide elimination. This research investigates the removal of 2,4-D via denitrification, with a particular emphasis on the effect of adding naturally generated volatile fatty acids (VFAs). The acids were produced from an acid-phase anaerobic digester with a mean VFA concentration of 3153±801 mg/L (as acetic acid). Initially, 2,4-D degrading bacteria were developed in an SBR fed with both sewage and 2,4-D (30-100 mg/L). Subsequent denitrification batch tests demonstrated that the specific denitrification rate increased from 0.0119±0.0039 using 2,4-D alone to 0.0192±0.0079 g NO₃-N/g VSS per day, when 2,4-D was combined with natural VFAs from the digester. Similarly, the specific 2,4-D consumption rate increased from 0.0016±0.0009 using 2,4-D alone to 0.0055±0.0021 g 2,4-D/g VSS per day, when using 2,4-D plus natural VFAs. Finally, a parallel increase in the percent 2,4-D removal was observed, rising from 28.33±11.88 using 2,4-D alone to 54.17±21.89 using 2,4-D plus natural VFAs.