石化廠油品污染使用地下水循環井處理短期成效實例探討

A Pilot Study to Evaluate the Short-Term Treatment Effectiveness of Groundwater Circulation Well Technology Used in an Oil Contaminated Petrochemical Plant

張耿榕(Keng-Jung Chang) ； 汪治田(Chih-Tien Wang) ； 許茹婷(Ju-Ting Hsu) ； 戴瑞賢(Jui-Hsien Tai)

《土壤及地下水污染整治》 2卷1期 (2015/01) Pp. 47-59

https://doi.org/10.6499/JSGR.2015.0201.005

摘要

地下水循環井（groundwater circulation well, GCW）可搭配曝氣、化學、生物等工法處理各種污染物，為一用途廣泛的現地土壤及地下水污染整治技術。本研究之目的，為探討短期內GCW處理石化廠內地下水中BTEX油品污染物之成效：試驗方法為於某地下水遭BTEX油品污染之石化廠場址，安裝單口GCW運轉45天，並同時監測地下水污染物BTEX濃度變化，以評估GCW系統之有效影響範圍及處理成效。試驗結果顯示，在設定處理量為5 m^3/hr操作條件下，有效影響半徑達15 m~20 m；系統上游由於污染被系統匯集反而使濃度短期內上升，下游之污染去除率則大致可達50%以上。以上結果顯示，GCW系統應用於石化廠油品污染改善，並非短期之內就能移除污染物，但仍能控制污染物往下游擴散，的確為有效的地下水油品污染整治方案。

關鍵字

地下水循環井 ； 油品污染

並列摘要

A Groundwater Circulation Well (GCW) is a kind of in-situ soil and groundwater remediation technology, which can be used with in-well aeration, chemical and biological treatment of a variety of industrial pollutants. The purpose of this study is to evaluate the GCW applicability in a petrochemical plant, and assess its effectiveness with regard to the short-term treatment of oil contaminated groundwater. The main pollutants include benzene, toluene, ethylbenzene and xylene (BTEX). One GCW system was installed in the pilot field and operated for 45 days to monitor the changes in BTEX concentration in the groundwater and assess the GCW radius of influence (ROI) and its treatment effectiveness. The results showed the GCW operating condition of processing flow at 5 m^3/hr gave an effective ROI of 15 m to 20 m. The upstream monitoring well concentration increased in the short term due to the use of the GCW system. As for the downstream monitoring wells, the concentration showed more than 50% removal during the operating period. As a pollution control facility, the GCW system takes time to remove groundwater contaminants completely within the ROI range, but it shows a good applicability to effectively prevent pollutants from spreading to the downstream area for oil contaminated petrochemical plants that remain in operation. 1. Introduction Pollutant hotspots are usually found near the source of a leak. High concentrations of contaminants are difficult to remove in a short time and easily spread to the downstream area along with the groundwater flow, causing the area of contamination to expand. Therefore, the key point for dealing with groundwater contaminated plants that remain in operation is how to remove pollutant hotspots effectively, and thus prevent the pollutants from expanding outside the site boundary. A Groundwater Circulation Well (GCW) is a kind of in-situ soil and groundwater remediation technology. By inducing a circulating flow field, it can efficiently remediate contaminated groundwater, and it can be combined with a variety of treatment technologies based on the type of contamination that is being addressed. GCW can be set to handle pollutant hotspots, or the vertical groundwater flow in the downstream direction, with multi-port loop wells used as a pollution prevention wall. Since a GCW is small footprint system, which can remediate groundwater and soil at the same time, and does not cause the water table to drawdown, is quite suitable for factory contaminated sites. This study examined a petrochemical plant groundwater contaminated site to assess the applicability and effectiveness of a GCW treatment system. The main pollutants at this site are benzene, toluene, ethylbenzene and xylene (BTEX). 2. Material and Methods A GCW system was installed of at the pilot site and operated for 45 days to monitor the changes in BTEX concentrations in the groundwater and assess the GCW radius of influence (ROI) and its treatment effectiveness. 3. Results and Discussion After 45 days of operation various effects were found in each well, as follows. 1. Upstream within the ROI scope: Because contaminants were gathered by the GCW system, the upstream monitoring well concentration increased, especially in shallow aquifers. 2. The upstream and downstream junction within the ROI scope: There were fluctuations in the concentration due to the GCW, but no significant increases or decreases. 3. The downstream within the ROI scope: Not only was upstream pollution was captured, but contaminants in the original position were also removed by the GCW system, thus showing effective pollution control. 4. The downstream outside the ROI scope: Although upstream pollutants were captured, there was no mechanism to remove contaminants, and the natural flow of the groundwater was relied on to dilute or remove pollutants from the original area. The original concentrations of the pollutants were too high, so it did not show an obvious reduction in a short period of time. However, the system was shown to be more effective with regard to the lower concentrations of dissolved phase contaminants, with a removal rate of more than 50% results during its use. 4. Conclusions This study applied the GCW technique to a petrochemical plant and found that it was unable to remove all the groundwater contaminants in the short term. As a pollution control facility, the GCW system is able to effectively control the diffusion of pollutants, preventing them from spreading to the downstream area and removing gradually contaminants in the ROI scope. The GCW is thus an effective method to control groundwater contaminants in relation to petrochemical plants that remain in operation.

並列關鍵字

groundwater circulation well ； oil contaminated