Effect Of Goethite On The Decomposition Of 2,4-dinitrophenol In Methanogenesis And Denitrification System

Phenolic compounds are persistent organic pollutants,widely distributed in the water environment.Due to nitro-benzene compounds’ great and far-reaching harm on human health and ecological environment,they have aroused widespread concern of domestic and foreign researchers.In this paper,2,4-DNP(2,4-dinitrophenol)was used as the representative.The effects of goethite and 2,4-DNP on methane production and denitrification were investigated.The effects of goethite on the degradation and transformation of 2,4-DNP in anaerobic methanogenesis and denitrification system were investigated.The intermediate products of biotransformation were analyzed by LC-MS.And microbial communities were analyzed by means of molecular biology method(PCR-DGGE).The main conclusions are as follows:1)2,4-DNP could be decomposed effectively in both anaerobic methanogenic and anaerobic denitrification system.The degradation efficiency was almost 100%.In addition,the degradation rate of 2,4-DNP was accelerated with the increase of the amount of goethite.2)The production of methane was inhibited by 2,4-DNP in anaerobic methanogenic system.The production of nitrogen was also inhibited by 2,4-DNP in anaerobic denitrification system.But,adding goethite could reduce the inhibition of 2,4-DNP on producing nitrogen and reduced more obviously with the increase of goethite.3)In anaerobic methanogenic system,the intermediate products were 2-nitrophenol,4-nitrophenol,2,4-diaminophenol,2-amino-4-nitrophenol(or 2-nitro-4-aminophenol)and benzoate.But 2-amino-4-nitrophenol(or 2-nitro-4-aminophenol)was not detected when adding goethite.The presence of goethite promoted the degradation of intermediates.4)In the denitrification system,the intermediate products were 2-nitrophenol,4-nitrophenol,2,4-diaminophenol and 2-amino-4-nitrophenol(or2-nitro-4-aminophenol).The products was detected only 2-nitrophenol and4-nitrophenol when adding the goethite.The presence of goethite promoted the degradation of intermediates.5)In anaerobic methanogenic system,the main strains of degrading 2,4-DNP were Clostridium cylindrosporum and Methanosarcina thermophila TM-1.The addition of goethite could promote the growth of microorganisms of degrading 2,4-DNP(Clostridium cylindrosporum,Clostridium sp.Strain Ade.TY and Methanosarcina sp)or aromatic compounds(Actinobacteria bacterium,Clostridiales bacterium mt11 andKurthia huakuii).6)In the denitrification system,the main strains of degrading 2,4-DNP were Clostridium sp.Strain Ade.TY.The addition of goethite could promote the growth of microorganisms(Actinobacteria bacterium,Kurthia huakuii and Sporobacter),which could degrade aromatic compounds to promote the degradation of 2,4-DNP.