Rapid Removal Of Suspended Cadmium From Three Types Of Farmland Irrigation Water And Its Mechanis

The aspects Aquaculture wastewater: In this paper,the effect of adding plants and suspended matter(SS)on the sedimentation rate of aquaculture wastewater was studied.The results showed that,under natural conditions,the removal efficiency was only 35.88% at 48 hours,and the removal efficiency was very low.After adding the plant,the removal efficiency reached 76.10%.Plants can make suspended Cd quickly settle through the action of adsorption,absorption,root exudates and root microorganisms.After adding plants and suspended matter to the aquaculture wastewater,the removal efficiency reached 81.75%.It can remove Cd efficiently and stably.Both plants and suspended matter can cause heavy metals to settle quickly.The aspects Mine wastewater: In this paper,the effects of different concentrations of humic acid,different ionic strength and different p H on the removal rate of trace cadmium(Cd)were investigated.The mechanisms that underlie this process were investigated in detail.At one hour,the Cd removal efficiency of the humic acid-added sample was 11.80% higher than that of the soil sample.The increase of humic acid also increased the adsorption point of the soil,resulting in accelerating sedimentation.The combination of SEM-element mapping and XPS spectrogram analysis,humic acid contains a large amount of amine groups,and the soil-20% HA sample sediment contains Cd element,and humic acid complexes Cd through amine groups,and then attaches to ss Co-sedimentation.Adding humic acid can make Cd settle more quickly,and the best effect of soil-20% HA sample.The effect of changing the ionic strength of the sample on the sedimentation effect of Cd was not obvious.p H is an important factor affecting the sedimentation rate of Cd.The higher the p H,the faster the Cd sedimentation.The results show that adding humic acid and increasing the p H can accelerate the Cd sedimentation rate.The aspects domestic sewage: This study investigated the removal of trace cadmium(Cd)from irrigation water using a synergistic approach involving water hyacinth(Eichhornia crassipes L.)and supplementation of phosphate fertilizer.The results show,The application of water hyacinth-phosphate fertilizer(WH-PF)removed Cd effectively and rapidly through synergistic flocculate formation.The Cd removal efficiency of this new process was 12 times higher than that of the control in the presence of plant root exudates,while the removal velocity was 36 times faster under the condition of 0.75 g/L WH-PF.At an initial Cd concentration of 40 μg/L in the irrigation water,Cd concentration was reduced to less than 3.5 μg/L after 2 h of treatment.Automated potentiometric titration in combination with chemical analysis revealed the presence of large quantities of amino acids-containing polysaccharides in the root exudates of E.crassipes,which played a major role in the neutralization of negative charges on SS and then increasing the flocculate settlement velocity.Additionally,phosphate fertilizer decreased the Zeta potential of SS by increasing the Fe3+/Fe2+ ratio in the aquatic environment.Our study showed that a WH-PF application can remove trace level of Cd quickly and effectively from farmland irrigation water.