In this study, an improved DRASTIC model, including the DRASTIC-LTPD model and the AHP-DRASTIC-LTPD model, with the addition of four extra evaluation factors, including land use type (L), aquifer thickness (T’), aquifer potential (P) and pollution source distance (D’), was constructed and compared to assess the groundwater vulnerability around farmland area in Shuangsheng Industrial Park, Sichuan Province, China. From the vulnerability grading charts of the traditional DRASTIC model, the improved DRASTIC-LTPD model and the AHP-DRASTIC-LTPD model, it showed that the vulnerability presented a lower level in the western and eastern farmland areas, whereas a higher level was in the central industrial park area. This result was consistent with the actual situation where groundwater recharge by rivers, regional land use, and human activities were more active in the middle in these areas. Nevertheless, the area at the same level of vulnerability varied greatly from model to model. The vulnerability index V-level region ratio calculated by the AHP-DRASTIC-LTPD model was 0, indicating that the distribution of vulnerability was smoother without the appearance of extremely good or poor conditions. From the present study, it was revealed that the AHP-DRASTIC-LTPD model could effectively reflect the impact of human activities and dilution on groundwater vulnerability. The adopted AHP method was also of high accuracy to empower the evaluation index leading to a more reliable evaluation results of regional groundwater vulnerability in comparison with the other two models. Therefore, this research could be employed as a reference for the evaluation of groundwater pollution around other similar unplanned industrial parks.
The exploitation of shale gas resources brings in abundant hazardous oil-based drilling cuttings (ODBCs). Herein, N, N-Dimethylcyclohexylamine (DMCHA) acted as the CO2 switchable hydrophilic solvents (SHSs), and the OBDCs treated with DMCHA were studied, especially priority pollutant migration and produced wastewater assessment during the extraction process. The petroleum hydrocarbon content of OBDCs decreased from 10.73 to 0.84 wt% after the DMCHA extraction was conducted at a DMCHA/OBDCs liquid–solid ratio of 20:1, 35 °C, and 200 rpm for 30 min. Using the CO2 switchability of SHSs, the petroleum hydrocarbon and DMCHA were recovered. There was wastewater, which was produced after recovering DMCHA, and the produced wastewater assessment showed that chemical oxygen demand, 5-day biochemical oxygen demand, total nitrogen, total organic carbon, and petroleum were 561.00, 238.00, 40.60, 309.00, and 0.27 mg/L, respectively. Meanwhile, phenols (0.0031 mg/L), naphthalene (0.0000129 mg/L), phenanthrene (0.000059 mg/L), anthracene (0.000058 mg/L), as well as heavy metal ions such as Cu (0.01 mg/L) could be detected in the produced wastewater. As a result, a priority pollutant migration mechanism from ODBCs to the produced wastewater was proposed. This would be helpful for the better management policy making of the ODBCs treated by using CO2 SHSs and the produced wastewater.
Against the background of sustainable development, landfill covers can consist of a range of materials, from clay to geocomposite and polymer composites. Given engineering and environmental requirements, we analyzed the performance and sustainability of four sanitary landfill cover materials, namely clay, HDPE, PVC, and GCL. Within the principles of environmentally sustainable design, we constructed a material selection index based on the performance as well as the economic and environmental impacts of the materials. In addition, using a data envelopment analysis (DEA) model with an analytic hierarchical process (AHP) preference cone, we developed a C2WH model to evaluate the performance of the selected materials. Through the calculation, we found that the comprehensive indexes of the four covering materials were E1 = 0.2600, E2 = 0.5757, E3 = 0.7815, and E4 = 1.0000, respectively. Our results indicated that the investigated materials could be ranked according to performance as follows: GCL > PVC > HDPE > clay. Thus, our results showed that GCL, with the highest efficiency value, was the optimal cover of the investigated materials. The multiobjective decision model developed in our study can be used as a technical reference and offers support for the selection of eco-friendly landfill cover materials.
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