Accidental spills of hydrocarbons from underground storage tanks or pipelines are a common cause of subsurface contamination. Anthropogenic hydrocarbon contamination of soil is a global issue throughout the industrialised world. In England and Wales alone, 12% of all serious contamination incidents in 2007 were hydrocarbon related. Biodegradation could be in situ process leading to a decrease of benzene concentrations in groundwater. Recently, monitored natural attenuation has become an effective alternative to the more active remediation methods for the in situ treatment of contaminated subsurface environments. The main objective of this study was to examine the possibility of adopting monitored natural attenuation as a remediation technique for the contaminated groundwater aquifer. In this natural attenuation study, the following tasks were conducted bioremediation investigation, biological first-order decay rates, Mann-Kendall Test model and BIOSCREEN model for the contaminated groundwater aquifer. In this study, a full-scale natural bioremediation investigation was conducted at a petroleum hydrocarbon spill site. In this study, The calculated biodegradation capacity (8.261 mg/L) at this site is much higher than the detected concentrations of petroleum-hydrocarbons (3-4 mg/L) within the most contaminated area inside the plume. Thus, natural biodegradation should be able to remove the contaminants effectively. The calculated biological first-order decay rates for benzene were between 1.7¡Ñ10-3-9.0¡Ñ10-4 day-1 respectively. Mann-Kendall test was applied to analyze the trend of contaminant variations. Results show that the S-value of monitor wells SW-1W, SW-4W, SW-42W, SW-23W, SW-30W, SW-67W and SW-70W were -2.23607, -1.16276, -1.52053, -1.34164, -1.26323, 0 and -1.34164, respectively. The negative S values reveal that the all contaminants tended to decrease. This indicates that the hydrocarbon plume at this site is not expanding, and has been contained effectively by the natural attenuation mechanisms. BIOSCREEN model from the groundwater analyses indicate, a first-order decay model reached the downgradient monitor well located 220 m from the spill location. that approximately 89% of the contaminate removal was due to biodegradation processes. The study of petroleum-hydrocarbons bacterial consortium were include Aquincola tertiaricarbonis L10¡BBosea sp. GR060219¡BBrachymonas petroleovorans strain CHX¡BHydrogenophaga sp. p3(2011)¡BHydrogenophaga sp.¡BMethylibium sp. YIM 61602¡BMycobacterium sp.¡BRhodoferax sp. IMCC1723¡BRhodoferax sp.¡BUncultured Rhodocyclaceae bacterium clone Elev_16S_975¡BUncultured Rhodocyclaceae bacterium clone eub62B1¤ÎUncultured Beggiatoa sp. clone GE7GXPU01BJTWR. Thus, the in situ bioremediation technology has the potential to be developed into an environmentally, economically and naturally acceptable remediation technology. Evidences for the occurrence of natural attenuation include the following: (1) depletion of dissolved oxygen, nitrate, and sulfate; (2) production of dissolved ferrous iron, sulfide, and CO2; (3) decreased BTEX concentrations and BTEX as carbon to TOC ratio along the transport path; (4) increased alkalinity and microbial species; (5) limited spreading of the BTEX plume; and (6) preferential removal of certain BTEX components along the transport path. Results indicate that natural attenuation can effectively contain the plume, and biodegradation processes played an important role on contaminant removal.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0630111-005421 |
| Date | 30 June 2011 |
| Creators | Lee, Ya-Chuan |
| Contributors | Long-chem Wu, Sheng-Lin Hou, Tzai-Tang Tsai, Chih-Ming Kao |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0630111-005421 |
| Rights | not_available, Copyright information available at source archive |
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