Degradation Of Chloroacetamide Pesticide And Ethane Sulfonic Acid Products By Microorganism And High Valence Manganese

The chloroacetamide pesticide is one of the world’s largest amount pesticide. In addition to present in the soil, the chloroacetamide pesticide is easy to transfer by infiltration to shallow groundwater and stormwater runoff into surface water after applied to farmland, and easily transformed into ethane sulfonic acid (ESA) which is more persistent and soluble than the parent compounds. Meanwhile toxicities such as endocrine disruption have been found in both the chloroacetamide pesticide and their ethanesulfonic acid products, as a result, there is an urgent need to remove such substances. In this study, alachlor, acetochlor, alachlor ESA and acetochlor ESA were chosed as the object compounds, the degradation of these four substances by microorganism and high valence manganese were studied.A highly effective acetochlor-degrading bacterial strain D-12was isolated from the soil. The strain was identified as Achromobacter sp. based on its16S rRNA gene sequence analysis. The optimum pH and temperature for strain D-12degradation of acetochlor in mineral salts medium (MSM) were7.0and30℃, respectively. Studies on biodegradation the enantiomers of acetochlor showed no significant enantioselectivity. The intermediate metabolites of acetochlor degradation were identified by high-performance liquid chromatography-mass spectroscopy (HPLC-MS) and gas chromatography-mass spectrometry (GC-MS). The results indicated that strain D-12may have potential application in bioremediation of acetochlor polluted environment.Studies showed that alachlor ESA and acetochlor ESA could be degradated by MnO2. Acidic conditions conducive to the conduct of the reaction. The presence of Na+, Ca2+and Fe3+had negative effects on the reaction and the inhibitory effects were exacerbated with increasing of these coexited ion concentrations, and the inhibitory effect of followed the order of Fe3+> Ca2+> Na+.The oxidation of alachlor and acetochlor by permanganate displayed autocatalytic phenomenon, that is, reduction product MnO2could catalyze alachlor and acetochlor degradated by KMnO4. But in the reaction of alachlor ESA and acetochlor ESA by KMnO4no autocatalytic phenomenon was observed. Comparison of the degradation of acetochlor and acetochlor ESA in KMnO4, MnO2, MnO2/KMnO4, and the adsorption of acetochlor, acetochlor ESA by MnO2shown that the mechanism of MnO2catalyticing KMnO4oxidation degradation of alachlor and acetochlor may due to the surface adsorption of MnO2, KMnO4is easier to oxidate the compounds adsorbed on the the MnO2surface. Inorganic complexing agent phosphate could strengthen KMnO4oxidation degradation of acetochlor, and with the increase of the phosphate content, KMnO4oxidative degradation of acetochlor faster; Low concentrations of EDTA and humic acid could strengthen the reaction, but the higher concentration of EDTA and humic acid would suppress the reaction.The above work demonstrated that microorganism and high valence manganese could remove the chloroacetamide pesticide and their ethanesulfonic acid products, offering two technologies for the treatment of wastewater containing chloroacetamide pesticide and ethanesulfonic acid products.