Spectroscopic Characterization And Adsorption Removal Of Dissolved Organic Matter From Coking Wastewater Bio-treated Effluent

The residual organics in coking wastewater bio-treated effluent, including long-chainalkanes, amines, benzene compounds, heterocyclic compounds, are components of dissolvedorganic matter (DOM).DOM involved chemical reactions in water phase, affecting aquaticplants growth and threatening drinking water safety because of the fact that it is one of theprecursors of disinfection byproducts.DOM characterization for the information ofcomposition, molecule structure, functional groups and so on is to guide the design andselection of advanced treatment techniques. To know the removal and transformation of theDOM helps to control and assess its environmental hazards.Given by the characterization methods including resin fraction, DOC, UV254, SUVA andUltraviolet-visible spectroscopy, fluorescence spectroscopy and Fourier transform infraredspectroscopy(FT-IR), DOM in coking wastewater bio-treated effluent was analyzedcarefully.Based on the spectroscopy results and specific characteristic parameters, analyzationwas conducted on the composition of DOM, the structure and functional groups. The changeand transformation of DOM in those aspects happened before and after activated carbonadsorption was also examined.Characterization of the DOM fractions displayed that hydrophobic acidic component(HoA), hydrophilic neutral component (HiN) and hydrophilic acidic component (HiA)are themost abundant fractions of DOC, accounting for39.88%,25.38%,20.85%, respectively.UV254and SUVA analysis showed that the degree of aromatic descending order is HiB> HoB>HoN> HiA> HoA> HiN.HiB was the fraction which has the highest degree of aromaticity andhighest proportion of unsaturated double band, with the highest SUVA value accounting for49.94L mg-1cm-1, HoA was the proportion with the highest degree of humification whichlead to poor biodegradability. HIS contained low molecular weight substances.Unsaturatedand aromatic characteristics of the components is determined by such structures such as C=C,C≡C, C=O and aromatic C=C skeleton structure, which was directly detected by FT-IRanalysis.Activated carbon adsorption experiments showed DOM, DOC and UV254removal rateswere57.56%,48.78%, respectively. The DOC removal rate followed the order: HIS> HoA> HoB>HoN, UV254removal rate order were HoA> HIS> HoB> HoN.UV254and SUVAanalysis shows that the activated carbon tend to remove the aromatic substances in HoA andthe non-aromatic material in HIS.Because of the adsorption of components with higherhumification degree in HoB, the biodegradability was improved. E2/E3value of HISincreased of27.5%after adsorption, indicating that the proportion of refractory material inHIS increased.Molecular weight decreaseed due to the adsorption process, as for HoB, it’s asignificant decrease.The adsorption process reduced the concentration of the fluorescentsubstance. The blue shift of a peak located in the aromatic protein like fluorescence regionobserved after the adsorption, which may be explained for the reduction of macromoleculecomponents.Fluorescence intensity (FI) showed that an important carbon source of DOMcomes from the biological source.