Study On Optimization Of Flocculation Technology For Landfill Leachate Treatment

Leachate is a kind of toxic and harmful organic wastewater with high concentration.If it is not treated properly,it will cause serious environmental pollution.Nowadays,membrane separation technology is an important leachate treatment technology.Usually leachate is discharged in standard after treatment,however it still has many problems,such as concentrated liquid can not be properly treated,separating operation is unstable,and so on.In this study,the molecular composition of biochemical effluent pollutants in leachate treatment process was investigated by using inductively coupled plasma emission(ICP),UV-Vis,three-dimensional fluorescence spectroscopy(EEM),electrospray ionization ion cyclotron resonance mass spectrometry(ESI FT-ICR MS).And the characteristics of the removal and transformation of the dissolved organic matter(DOM)in the process of three coagulation stages were studied which provide a rich theoretical basis for the design,development and optimization of the large-scale leachate treatment engineering process.In this paper,the effluent samples of leachate treatment process were characterized and the heavy metal ion was found in the raw water,while the concentration was low.Dissolved organic matter is rich in kinds of materials,protein and sugar and other easily degradable substances are less content,while contained a large number of refractory small molecules and more heteroatom compounds.Those dissolved organic matter had low degree of molecular oxidation,low degree of unsaturation,low aroma,high degree of humification,such unsaturated organic molecules are mainly 10 to 20 carbon atoms substances.After biochemical treatment section,pollutants transformation characteristics in different coagulation treatment stages had different removal effects: removal of macromolecules,high unsaturation containing carboxyl groups and hydroxyl groups are more significant and residual organic matters are mainly humic acids with relatively small molecular and low unsaturation with low double equivalent key value ketone structure with carbon and oxygen double bonds.Results of Fenton reagent treatment biogenic effluent transformation characteristics show that: humic acid,fulvic acid and dissolved microbial products have been significantly remove,at the same time,removal of macromolecules produce a large number of new small organic molecules organic matters.Most of the residual organic matters are heteroatom compounds containing one benzene ring or one heterocyclic ring and nitrogen containing compound is the largest group.In summary,by characterizing biochemical DOM in the leachate effluent,we found that those matters are mainly H/C = 1.5-2.0,O/C = 0-0.3 containing a large number of heteroatom which are mainly lipid structure materials compounds;oxygen element in the molecule is mainly ketone,ester structures;nitrogen element is mostly quaternary ammonium and other structures;benzene ring and heterocyclic structures are also abundant in the molecule.