Environmental science

A novel permeable reactive barrier for in-sit

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Credit: Kaixuan Zheng, Xingshen Luo, Yiqi Tan, Zhonglei Li, Hongtao Wang, Tan Chen, Li Zhao, Liangtong Zhan

A permeable reactive barrier, or “PRB,” is a wall constructed below ground to clean up contaminated groundwater. The wall is “permeable,” which means that contaminated groundwater can flow through the PRB to be treated. The reactive materials that make up the wall either trap harmful contaminants or make them less harmful. The treated groundwater flows out the other side of the wall. PRB has emerged as a promising and sustainable in situ groundwater remediation technology, which has the advantages of low maintenance costs, service longevity, and in situ treatment of a variety of groundwater pollutants (eg, heavy metals, inorganic and organic pollutants).

An appropriate PRB configuration is critical to the PRB engineering design, which should be selected considering site-specific hydrogeologic conditions and contaminant plume characteristics. The most common PRB configuration is the continuous permeable reactive barrier (C-PRB). This configuration has a simple structure, convenient installation, less disturbance to the natural groundwater flow field, and low sensitivity to the complexity of the groundwater flow field. However, for sites with deep groundwater depth and large plumes, the application of C-PRB is limited due to its high construction and material cost.

To overcome the shortcomings of the C-PRB, Prof. Hongtao Wang from the Tsinghua University, Dr. Tan Chen from the Minzu University of China and their team members have proposed an innovative and sustainable PRB configuration, namely the passive convergence-permeable reactive barrier (PC-PRB). The PC-PRB is designed to make the plume converge towards the PRB due to the passive hydraulic decompression-convergent flow effect. The corresponding passive groundwater convergence (PC) system is deployed upstream of the PRB system, which consists of passive wells, water pipes, and a buffer layer. This study entitled “Passive convergence-permeable reactive barrier (PC-PRB): an effective configuration to enhance hydraulic performance” is published online in Frontiers of Environmental Science & Engineering in 2022.

In this study, the research team developed a two-dimensional (2D) finite-difference hydrodynamic code, entitled PRB-Flow, to examine the hydraulic performance parameters (ie, capture width (W) and residence time (t) of PC-PRB. The research team found the horizontal 2D capture width (Wh) and vertical 2D capture depth (Wv) of the PC-PRB remarkably increased compared to that of the continuous reactive barrier (C-PRB). The aforementioned relative growth values ​​in order are greater than 50% and 25% in this case study. Therefore, the PRB geometric dimensions as well as the material cost required for the same plume treatment decreases. The sensitivity analysis reveals that the dominant factors influencing the hydraulic performance of the PC-PRB are the water pipe length (Lp), PRB length (LPRB), passive well height (Hw), and PRB height (HPRB). The discrepancy between the Wh of PC-PRB and that of the C-PRB (ie, ΔWh) has a low correlation with PRB parameters and mainly depends on Lp, which could dramatically simplify the PC-PRB design procedure. Generally, the proposed PC-PRB exhibits an effective PRB configuration to enhance hydraulic performance.

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About Higher Education Press

Founded in May 1954, Higher Education Press Limited Company (HEP), affiliated with the Ministry of Education, is one of the earliest institutions committed to educational publishing after the establishment of PR China in 1949. After striving for six decades, HEP has developed into a major comprehensive publisher, with products in various forms and at different levels. Both for import and export, HEP has been striving to fill the gap of domestic and foreign markets and meet the demand of global customers by collaborating with more than 200 partners throughout the world and selling products and services in 32 languages ​​globally. Now, HEP ranks among Chinas top publishers in terms of copyright export volume and the worlds top 50 largest publishing enterprises in terms of comprehensive strength.

The Frontiers Journals series published by HEP includes 28 English academic journals, covering the largest academic fields in China at present. Among the series, 13 have been indexed by SCI, 6 by EI, 2 by MEDLINE, 1 by A&HCI. HEPs academic monographs have won about 300 different kinds of publishing funds and awards both at home and abroad.

About Frontiers of Environmental Science & Engineering

Frontiers of Environmental Science & Engineering (FESE) is the leading edge forum for peer-reviewed original submissions in English on all main branches of environmental disciplines. FESE welcomes original research papers, review articles, short communications, and views & comments. All the papers will be published within 6 months since they are submitted. The Editors-in-Chief are Prof. Jiuhui Qu from Tsinghua University, and Prof. John C. Crittenden from Georgia Institute of Technology, USA. The journal has been indexed by almost all the authoritative databases such as SCI, Ei, INSPEC, SCOPUS, CSCD, etc.


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