Ciampi Paolo, Esposito Carlo, Bartsch Ernst, Alesi Eduard J, Rehner Gert, Papini Marco Petrangeli
Department of Earth Sciences, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
CERI Research Center, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
Heliyon. 2022 Nov 3;8(11):e11402. doi: 10.1016/j.heliyon.2022.e11402. eCollection 2022 Nov.
An innovative Groundwater Circulation Well (GCW) process was configured, installed, and tested for optimizing the distribution of a soluble nutrient supplement in a heterogeneous aquifer for reductive dehalogenation. This generated an in-situ bioreactor for the enhanced treatment of chlorinated aliphatic hydrocarbons (CAHs). At a site in Barcelona, Spain, trichloroethylene (TCE) concentration was found in the source area to a maximum value of up to 170 mg/L, while the degradation products like 1,2-dichloroethylene (1,2-DCE) and vinyl chloride (VC) were detected in significantly lower concentrations or were even absent. The novel system combined a vertical recirculation well (IEG-GCW®) and four multilevel injection wells (IEG-MIWs) to introduce the carbon solution into the aquifer. A 12 m deep IEG-GCW® equipped with 2 screened sections were located in the center of the 4 IEG-MIWs. The GCW induced flow moves the groundwater in an ellipsoidal recirculation cell to spread the supplements from the central GCW and from the peripheral MIWs in the aquifer body. Two multilevel sampling wells (IEG-MLSWs®) in the radius of influence (ROI) monitor the remediation process to capture hydrochemical variations along the vertical aquifer sections. A multi-source model harmonizes geological and hydrochemical information during different remediation stages, guiding the adaptation of the remediation strategy to physicochemical conditions and unmasking the decontamination mechanics induced by the remedial actions. Hydrochemical monitoring of MLWS and the stable carbon isotopic signature of cis-1,2-DCE and VC show the mobilization of secondary contamination sources triggered by recirculation during remediation, the stimulation of microbiological activity following nutrient supplement via GCW and MIWs, and the strong decrease of CAHs concentrations at different aquifer levels. Evidence from the first application at the field scale reveals a significant increase in the chloroethane biodegradation rate and short-term effectiveness of the innovative remediation strategy. GCW-MIWs synergy represents a promising strategy to degrade CAHs in a shorter period through the combination of a controllable hydraulic system, effective nutrient distribution, and the monitoring of the remediation process.
设计、安装并测试了一种创新的地下水循环井（GCW）工艺，以优化可溶性营养补充剂在非均质含水层中的分布，用于还原脱卤。这产生了一个原位生物反应器，用于强化处理氯代脂肪烃（CAH）。在西班牙巴塞罗那的一个场地，源区三氯乙烯（TCE）浓度最高达170 mg/L，而降解产物如1,2 - 二氯乙烯（1,2 - DCE）和氯乙烯（VC）的检测浓度则显著较低甚至未检出。该新型系统结合了一口垂直循环井（IEG - GCW®）和四口多级注入井（IEG - MIW），将碳溶液引入含水层。一口12米深、配备2个筛管段的IEG - GCW®位于4口IEG - MIW的中心。GCW诱导的水流使地下水在椭圆形循环单元中流动，从而在含水层主体中扩散来自中央GCW和周边MIW的补充剂。影响半径（ROI）内有两口多级采样井（IEG - MLSW®）监测修复过程，以获取沿垂直含水层剖面的水化学变化。一个多源模型协调不同修复阶段的地质和水化学信息，指导修复策略适应物理化学条件，并揭示修复行动引起的去污机制。MLWS的水化学监测以及顺式 - 1,2 - DCE和VC的稳定碳同位素特征表明，修复过程中的循环引发了二次污染源的迁移，通过GCW和MIW补充营养后刺激了微生物活性，以及不同含水层水平处CAH浓度的大幅下降。现场规模首次应用的证据显示，氯乙烷生物降解率显著提高，创新修复策略具有短期有效性。GCW - MIW协同作用代表了一种有前景的策略，通过可控水力系统、有效营养分布和修复过程监测的结合，在更短时间内降解CAH。
