Numerical modeling of geological sequestration of brine wastewater due to coal mining in the Ordos Basin, China

Copyright © 2023 Elsevier B.V. All rights reserved..

The coal resources play an indispensable role in the development of heavy industry in China, and coal mining activity leads to brine wastewater drainage, causing major risks for the aquatic environmental system. Thus, the effective and economic treatment of coal mine wastewater is vital to mitigate the environmental burdens, and geological sequestration by deep-well injection is a promising treatment technique. This study elucidates the physical and geochemical processes of coal mine wastewater transport in deep reservoirs and proposes an optimized injection scheme to satisfy environmental and economic benefits simultaneously in the Ordos Basin, China. First, a variable density and variable parameter groundwater reactive transport model is constructed to simulate the long-term process of deep-well injection for coal mine wastewater treatment. Then, the environmental metrics, i.e., the percentage of permeability reduction, the total mass and spatial second moment of the wastewater plume, and the economic metric defined as achieving a higher concentration at a higher injection rate are proposed to evaluate the performance of the injection scheme. The simulation results show that the secondary mineral anhydrite dominates the reduction of reservoir permeability due to the precipitation reactions with SO42- in the brine wastewater, and the permeability in the reaction zone decreases by 0.66 % ~ 1.26 % after 10 years in the basic scenario. Moreover, higher concentrations negatively affect reservoir permeability and increase total dissolved solids, while higher injection rates decrease reservoir permeability and increase the brine wastewater plume. The study also identifies promising schemes that can achieve an optimal trade-off between the conflicting metrics. Based on the economic and environmental benefits demanded in this study, an injection scenario with a concentration of C4 and an injection volume of 800 m3/d is recommended to maximize environmental benefits. Overall, this numerical study offers significant implications for designing an economically and environmentally sustainable treatment injection scheme for coal mining wastewater drainage.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

2023

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:908

Enthalten in:

The Science of the total environment - 908(2023) vom: 15. Jan., Seite 168580

Sprache:

Englisch

Beteiligte Personen:

Du, Zhuoran [VerfasserIn]
Song, Jian [VerfasserIn]
Du, Song [VerfasserIn]
Yang, Yun [VerfasserIn]
Wu, Jianfeng [VerfasserIn]
Wu, Jichun [VerfasserIn]

Links:

Volltext

Themen:

Brine wastewater disposal
Deep-well injection
Geochemical reaction
Journal Article
Numerical modeling
PFLOTRAN

Anmerkungen:

Date Revised 25.11.2023

published: Print-Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.1016/j.scitotenv.2023.168580

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM364592192