Experimental investigations on spreading and displacement of fluid plumes around an injection well in a contaminated aquifer

• Published in: Journal of hydrology (Amsterdam) Vol. 617; p. 129062
• Main Authors: Du, Zhipeng, Chen, Jiajun, Ke, Shengnan, Xu, Qi, Wang, Zhenquan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2023
• Subjects: Agent driving; Contamination plume; groundwater contamination; groundwater flow; Mixing–Dispersion; oxidants; potassium permanganate; Radial injection; remediation; Agent driving; Radial injection; Mixing–Dispersion; Contamination plume
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2023.129062

[Display omitted] •The mechanism of interaction between the remediation agent injection, agent mixing, and contamination plume expansion was explored.•The imaging method for plume detection was established and verified.•A model was developed to quantify the radial driving (oxidant plume), displacement (contaminant plume), and mixing.•Radial injection of solute driving, mixing, and spreading was greatly affected by dispersion. ｄe concentration of the injected fluid decays smoothly around the location of the corresponding sharp interface, which is beyond the theoretical range. This concentration spread should be considered in redefining outer mixing boundaries around injection well between the injected and ambient contaminated solutions. In this study, a radial transport experiment was performed (naphthol green B was first injected as a contaminant plume followed by potassium permanganate as the remediation agent) to mimic the interface mixing in more realistic conditions. The radial advection–dispersion model (e.g., dominated by interfacial driving, R (C/C0 = 0.5), combined with dispersion mixing) was used to obtain the position of the “boundary”, rf, at the mixing fringe of the injected fluid. The results show that the injected oxidant front ran after the contaminated plume at a migration velocity of more than 1.29 times, increasing the mechanical dispersion difference between potassium permanganate and naphthol green B. The increase in the injection rate and ambient groundwater flow velocity improved the mixing of oxidant and contaminated plume (the area difference between the contaminated plume and the oxidant decreased) but also accelerated the contaminated plume coverage. Changing the injection mode (such as linear injection) was an effective method, which enhanced the mixing of the oxidant-contamination plume and weakly expanded the contaminated plume (The swept area, 254 cm2, was the smallest among the three injection modes). The relationship between injection and mixing needs to be further strengthened.