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Title: Establishing Vadose Zone Slow-Release Carbon Sources for Enhanced Bioremediation Using Silica Suspension

Abstract

Delivery of C sources (nutrients) to the vadose zone and establishing a slow-release C source in this unsaturated zone are essential for promoting long-term, enhanced contaminant bioremediation at sites with deep vadose zones, such as the Hanford Site in the southeast of the state of Washington. Conventional solution-based injection and infiltration approaches face challenges in achieving delivery goals. Aqueous colloidal silica suspension has characteristics that can potentially be used for nutrient delivery and slow-release source setup. This research was conducted to (i) demonstrate delayed gelation of colloidal silica suspensions with the presence of nutrients; (ii) prove that gelation takes place in sediment and the gel slowly releases nutrients; and (iii) show that silica suspensions are injectable for vadose zone emplacement. Results demonstrated that nutrient-laden colloidal silica suspensions have low initial viscosity and then increase in viscosity with time until reaching gelation, allowing for a slow release of nutrients into the environment. Higher salt and silica concentrations increased the rate of viscosity climbing and the rate of gelation, whereas higher silica concentrations resulted in stronger gels. Nutrients were slowly released from gels in both batch and column experimental settings. The rheological and injection behavior of the silica suspensions revealed the injectabilitymore » of these fluids. This study demonstrated that colloidal silica suspension could be used as a carrier to distribute nutrients to the vadose zone and to establish slow-release nutrient sources.« less

Authors:
 [1];  [1];  [2]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Energy and Environment Directorate
  2. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Process Engineering
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1511145
Alternate Identifier(s):
OSTI ID: 1463339
Report Number(s):
PNNL-SA-134023; PNNL-SA-129486
Journal ID: ISSN 1539-1663
Grant/Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Vadose Zone Journal
Additional Journal Information:
Journal Volume: 17; Journal Issue: 1; Journal ID: ISSN 1539-1663
Publisher:
Soil Science Society of America
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Zhong, Lirong, Lee, Brady, and Yang, Shuo. Establishing Vadose Zone Slow-Release Carbon Sources for Enhanced Bioremediation Using Silica Suspension. United States: N. p., 2018. Web. doi:10.2136/VZJ2017.09.0175.
Zhong, Lirong, Lee, Brady, & Yang, Shuo. Establishing Vadose Zone Slow-Release Carbon Sources for Enhanced Bioremediation Using Silica Suspension. United States. doi:10.2136/VZJ2017.09.0175.
Zhong, Lirong, Lee, Brady, and Yang, Shuo. Thu . "Establishing Vadose Zone Slow-Release Carbon Sources for Enhanced Bioremediation Using Silica Suspension". United States. doi:10.2136/VZJ2017.09.0175. https://www.osti.gov/servlets/purl/1511145.
@article{osti_1511145,
title = {Establishing Vadose Zone Slow-Release Carbon Sources for Enhanced Bioremediation Using Silica Suspension},
author = {Zhong, Lirong and Lee, Brady and Yang, Shuo},
abstractNote = {Delivery of C sources (nutrients) to the vadose zone and establishing a slow-release C source in this unsaturated zone are essential for promoting long-term, enhanced contaminant bioremediation at sites with deep vadose zones, such as the Hanford Site in the southeast of the state of Washington. Conventional solution-based injection and infiltration approaches face challenges in achieving delivery goals. Aqueous colloidal silica suspension has characteristics that can potentially be used for nutrient delivery and slow-release source setup. This research was conducted to (i) demonstrate delayed gelation of colloidal silica suspensions with the presence of nutrients; (ii) prove that gelation takes place in sediment and the gel slowly releases nutrients; and (iii) show that silica suspensions are injectable for vadose zone emplacement. Results demonstrated that nutrient-laden colloidal silica suspensions have low initial viscosity and then increase in viscosity with time until reaching gelation, allowing for a slow release of nutrients into the environment. Higher salt and silica concentrations increased the rate of viscosity climbing and the rate of gelation, whereas higher silica concentrations resulted in stronger gels. Nutrients were slowly released from gels in both batch and column experimental settings. The rheological and injection behavior of the silica suspensions revealed the injectability of these fluids. This study demonstrated that colloidal silica suspension could be used as a carrier to distribute nutrients to the vadose zone and to establish slow-release nutrient sources.},
doi = {10.2136/VZJ2017.09.0175},
journal = {Vadose Zone Journal},
issn = {1539-1663},
number = 1,
volume = 17,
place = {United States},
year = {2018},
month = {4}
}

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