Qualitative and quantitative simulation of best management practices (BMPs) for contaminated megasite remediation using the SiteWise™ tool.

Remediation activities, particularly in megasites, may induce substantial secondary environmental impacts that must be addressed for green and sustainable remediation (GSR) practices. Only limited studies are available quantitatively assessing the environmental footprint and environmental benefits of implementing Best Management Practices (BMPs) in megasite remediation. This study used the SiteWise™ tool, a quantitative environmental footprint assessment for scenario simulation and benefit quantification of BMPs, on a contaminated megasite in Hebei Province, China. We observed a considerable environmental footprint and energy from the remediation. Taking the final implementation alternative (Alt 1) as an example, which is characterized by combining multiple remediation techniques, the greenhouse gas (GHG) emissions reached 113,474 t, the energy used was 2,082,841 million metric British thermal units (MMBTU), and other air pollutant emissions (NOx, SOx, and PM10) amounted to 856 t. Further BMP analyses highlighted the benefits of substituting the conventional solidification/stabilization agent with willow woodchip-based biochar, which could reduce GHG emissions by 50,806 t and energy used by 926,648 MMBTU. The overall environmental benefits of implementing all applicable BMPs in the remediation were significant, with a 66.85%, 50.15%, and 56.05% reduction in GHG emissions, energy used, and other air pollutants, respectively. Our study provides insights into quantifying the environmental footprint and exploring emission reduction pathways for contaminated megasite remediation. It also offers a feasible path for quantifying the environmental benefits of BMPs, promoting the development of GSR of contaminated sites.

Spatiotemporal dynamic temperature variation dominated by ion behaviors during groundwater remediation using direct current.

Direct current (DC) electric field has shown promising performance in contaminated site remediation, in which the Joule heating effect plays an important role but has been previously underappreciated. This study focuses on the spatiotemporal characteristics and mechanism of temperature change in heterogeneous porous media with applied DC. The heating process can be divided into four phases: preferential heating of the low permeability zone (LPZ), rapid heating in the middle region, temperature drop and hot zone shift, and reheating. The dynamic ion behaviors with complex interplays among reactions, electrokinetic-driven migration, and mixed convection induced an uneven redistribution of ions and dominated the heating rate and temperature distribution. The concentration of major ions near the pH jump decreased to 1% of the initial value, even though ions were continuously pumped into the heating zone. This ion depletion caused a drop in current, heating rate, and temperature. Here ions cannot be delivered rapidly into the ion-depleted zone by electromigration due to the potential flattening in the surrounding region. The presence of LPZ intensified the nonuniformity of ion redistribution, where a regional focusing of water-soluble ions was observed, and weakened the temperature rebound compared with that using homogeneous sand. These results provide a new perspective on the regulation of DC heating in site remediation.

[Environmental damages assessment: establishment of system framework in China].

Health injury, properties compensation and ecological and environmental destruction caused by environmental pollutions have become the focuses of the government, the public and the society at present in China. The experiences of developed countries have revealed that the environmental damage assessment system must be established through development of environmental damage assessment legislations, technologies and funding guarantee system suitable for the nation's conditions based on the specific environmental situation and main issues. China has some experience in marine ecological environment, fishery resources damage assessment, forest resources damage assessment and remediation management of contaminated sites; however, the managing function of environmental damage assessment is assigned to different governmental departments. There are also shortcomings such as few cases of environmental public compensation, insufficient environmental privacy determination and compensation, etc. Based on the methods of materials and information collections, questionnaires, visiting environmental court and government sectors, interviews to assessment organizations and professionals, launching practical assessments to related cases and participating in environmental public lawsuits, the situation of environmental pollution damages in China was analyzed, the related legislation and management mechanism were reviewed, the corresponding assessment organizations regarding environmental damages were sort out, and the funding sources of environmental damage assessment were explored. Aiming at the main issues in Chinese environmental damage management, a standard and unified system for environmental damage assessment based on current managing and technological systems is important to improve the practical work in determination, assessment and compensation of environmental pollution damage in China, and to further explore the feasible environmental damage quantitative management.