Wastewater Advanced Treatment For The Removal Of Effluent Organic Matter (EfOM) And Their Efficiency For Alleviating Ultrafiltration Membrane Fouling

Advanced treatments and reuse of wastewater is an important way for alleviationof water shortage in China. The water sample was fetched from the effluent ofpilot-scale SBR operated by key laboratory of water pollution control center. Thetreatment efficiency of activatied carbon （AC） adsorption, biological activatied carbon（BAC） filter, ozonation （O₃） and activatied carbon catalyzed ozonation （AC/O₃） forsewage effluent （SE） were ingvestigated. The main characteristics changes of theeffluent organic matter （EfOM） were investigated by using ultrafiltration separation,resin separation, permeation chromatography （GPC） analysis and fluorescenceExcitation-Emission Matrix Spectroscopy （EEM）, and the alleviation of ultrafiltrationmembrane fouling with AC adsorption, BAC filter, ozonation and AC/O₃pretreatments was further observed.AC was able to adsorb most of the effluent organic matter （EfOM） at abundantadsorption time and appropriate dosage. Allowing for the availability, it would be bestto keep the AC dosage below2.0g/L. Compared with the Langmuir equation,Modified Freundlich equation was more suitable for the simulation of the ACadsorption isotherm for EfOM. Pseudo-second-order kinetics equation was well suitedto interpret the AC adsorption kinetics for EfOM.Removal Efficiency of EfOM by BAC filter was limited with25%removal forDOC and UV₂₅₄. Organic matters （OM） with medium and small molecular weight（MW<10kDa） in the EfOM could be well eliminated by BAC filter. Furthermore，BAC filter could remove soluble microbial metabolites （SMPs）, humic acid materials,simple aromatic proteins and fulvic acids to some extent, especially for the SMPs.Stratified sampling showed that the decline of DOC and UV₂₅₄of EfOM were morequickly at the top20cm of the BAC colume （EBCT=60min） and10cm（EBCT=30min）. Extension of EBCT of BAC could strengthen the removal of EfOMespecially for the MW<1kDa components, while the influence of backwash on BACefficiency was not obvious.The removal of DOC in SE with ozonation was limited, while the decline ofUV₂₅₄and SUVA were significant. Meanwhile the biodegradability of EfOM waseffectively increased during ozonation. Determination of molecular weight distribution （MWD） showed that ozonation was prior to oxidize the macromolecularorganic matters in EfOM, thus increased the amount of small molecular components.Resin separation of EfOM found that ozonation could effectively reduce thehydrophobic components with strong ultraviolet absorption, thereby increase contentof hydrophilic components. EEM analysis demonstrated that ozonation couldeffectively remove the fulvic acid, microbial metabolites and humic acid organicmatters in SE.AC/O₃of original SE could result in rapid UV₂₅₄drops and more significantdecline of DOC than single ozonation. Moreover, the narrowing of MWD excent andweakness of ultraviolet absorption （especially for organic matter with high molecularweight） were observed duing the AC/O₃of original SE. Fulvic acids, microbialmetabolites and humic acids were also effectively removed. Increasing of AC dosage,reduction of the AC particle size could increase the DOC removal during the AC/O₃.But the DOC removal declined with the increasing of AC using numbers. In the weakacid condition （pH=3.7⁵）, AC/O₃had the best efficiency for EfOM removing.It wasexpected that EfOM removing by AC/O₃mainly carried out on the surface of AC withthe pH below6, and in the liquid phase with pH exceeding6.The alleviation of ultrafiltration （UF） membrane fouling with AC adsorption atshort adsoption time was limited. Only with enough long adsorption time （8h）, the IFand RF of UF membrane would be reduced. The normalized flux （J/J0） decline rate ofUF membrane remained unchanged with the BAC pretreatment （EBCT=30min and60min）, yet the IF of UF membrane decreased. Ozonation could effectively relieve theUF membrane fouling. With the extension of ozone dosage, the J/J0decline rate of UFmembrane decreased, the TF weakened, the IF gradually decreased with firstly slightincreasing, and the RF continued to decrease. AC/O₃pretreatment could effectivelyalleviate the UF membrane fouling. The J/J0decline rate of UF membrane, the TF andthe RF were decreasing. Moreower, with the increasing of initial pH of SE （pH=3⁹）,J/J0decline rate of UF membrane decreased, meanwhile the TF and RF of were alsoweakened. Studies revealed that UF membrane fouling was closely related with thecharacteristics of EfOM （such as MWD and hydrophility）, not determined by theEfOM content （DOC）.