Abstract

Industrial wastewater may have a long-time effect on the environment and human life as it goes underground and causes serious pollution continuously. To have a well understanding of the migration of such wastewater is a basic task for industrial wastewater treatment as well as industrial design. To study the migration mechanism of industrial wastewater in rock formations, the governing equations such as mechanics, seepage, heat, and mass transfer are reviewed, referenced, and proposed. The thermal (T)-hydraulic (H)-mechanical (M) coupled model of the multimedia of matrix-fault and matrix-fracture-fault is established. The influence of the fault and the fractures on the pressure distribution and contaminant migration is analyzed. The influence of fault length, width, dip angle, permeability, and temperature of wastewater on contaminant migration is parametrically studied. The following results can be obtained. (1) The fracture quantitively affects the concentration distribution, while the fault dominates the concentration distribution and contaminant migration. (2) The migration of the contaminants can be geometrically divided into 3 zones along the direction of the fault: the saturation zone, the rapid diffusion zone, and the concentration decrease zone. (3) There is a peak of the concentration along the bottom of the model. The position of the peak is the projection of the endpoint of the fault. (4) The fault length has the most significant effect on contaminant accumulation. The temperature of the wastewater has the minimum effect on the contaminant accumulation. (5) The accumulation of concentrations can be divided into 2 stages, the slow growth stage (before 20 years) and the rapid growth stage (after 20 years). The main channel of contaminant migration in the slow growth stage is a fault. During the rapid growth stage, the contaminants penetrate through the rock matrix as well as the fault.

Highlights

  • The great development of the society and economy of China leads the rapid growth in the industry

  • The temperature of the wastewater has the minimum effect on the contaminant accumulation

  • (5) The accumulation of concentrations can be divided into 2 stages, the slow growth stage and the rapid growth stage

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Summary

Introduction

The great development of the society and economy of China leads the rapid growth in the industry. The transport of contaminants in industrial wastewater in rock formation is the result of a combination of multiple physical fields, including thermal field, hydraulic field, and stress field. The fluid pressure changes in the hydraulic field due to the fluid flow behavior and affects the stress distribution in the rock formation, i.e., it influences the stress field. Rossen pointed out that the porefissure and interfracture seepage problems can be solved by the way of Darcy’s law and an anisotropic permeability tensor and proposed a method to characterize the anisotropic seepage in fractured rock masses using continuous medium theory [21]. The contaminant can be referred to as the common heavy metal ion such as Pb (plumbum) or Hg (mercury)

The Coupled THM Model
Equivalent Continuous Medium Model Theory
Ks ðp p0Þ αT ðT
Migration in the Multimedia under the Coupled THM Effects
Effect of the Fault Parameters on Contaminant Migration
Conclusions
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