Effect Of Fulvic Acid And Cu(Ⅱ) On The Suspended Particles Clogging Of Porous Media During Artificial Recharge

Artificial recharge of groundwater is an effective measure to solve the problem of groundwater overexploitation,and the clogging of suspended particles is a technical bottleneck affecting recharge.Fulvic acid widely exists in reinjection water and aquifers,because it contains a large number of phenolic hydroxyl groups,carbonyl groups and other groups,which will interact with suspended particles and affect the migration and deposition behavior of suspended particles in aqueous media.There are more Cu(Ⅱ)in the reinjection water,Cu(Ⅱ)can be adsorbed by complexation with fulvic acid and ion exchange with suspended particles.Fulvic acid and Cu(Ⅱ)may affect the clogging of suspended solids in aqueous media during artificial recharge.In this study,the adsorption of fulvic acid and Cu(Ⅱ)with kaolin particles was studied by batch adsorption test,and the changes of surface structure(functional group)and surface properties(Zeta potential,particle size)of kaolin particles before and after adsorption were determined,so as to analyze the changes of migration ability of kaolin particles in aqueous medium.The effects of fulvic acid,Cu(Ⅱ)and their coexistence on the clogging of suspended solids in aqueous media were studied by indoor seepage sand column test.Cu(Ⅱ)(CU group),kaolin(SS group),fulvic acid+kaolin(SS+FA group),Cu(Ⅱ)+ kaolin(SS+CU group)and fulvic acid+Cu(Ⅱ)+ were adopted respectively.In this study,the temporal and spatial variation law of permeability of water-bearing medium was determined,and the deposition amount of suspended matter in each seepage section was found out,thus systematically clarifying the influence mechanism of fulvic acid and Cu(Ⅱ)on the clogging of suspended matter in water-bearing medium.The main results are as follows:(1)The data of kaolin adsorbing fulvic acid and kaolin adsorbing Cu(Ⅱ)are fitted by Langmuir and Freundlich models,and it is found that the adsorption of kaolin adsorbing fulvic acid and kaolin adsorbing Cu(Ⅱ)are more in line with Langmuir model.(2)Except for SS+CU group,the mobility of suspended particles in other experimental groups is SS+FA group > SS+CU group > SS+FA+CU group > SS group.(3)Adding fulvic acid or Cu(Ⅱ)alone will promote the degree of suspended solids clogging in aqueous media,while adding fulvic acid and Cu(Ⅱ)will also aggravate the degree of suspended solids clogging,but compared with SS+FA group and SS+CU group,this intensification is obviously inhibited.(4)At the end of reperfusion,CU group was severely clogged(0<K’<0.30)in AB layer(0-1.5 cm),moderately clogged(0.30≤K’<0.60)in BC layer and slightly clogged(0.60≤K’<1)in CD and DE layer.In SS group and SS+FA+CU group,the upper layer(0-7.5 cm)was severely clogged and the bottom layer was moderately clogged.SS+FA and SS+CU groups are severely clogged in the water-bearing medium in each seepage section(0-10.50 cm).