Engineering behavior of biofilm amended earthen barriers used in waste containment

John L. Daniels (Department of Civil Engineering and Global Institute for Energy and Environmental Systems, University of North Carolina, Charlotte, North Carolina, USA)
Raghuram Cherukuri (Department of Civil Engineering and Global Institute for Energy and Environmental Systems, University of North Carolina, Charlotte, North Carolina, USA)
Helene A. Hilger (Department of Civil Engineering and Global Institute for Energy and Environmental Systems, University of North Carolina, Charlotte, North Carolina, USA)
James D. Oliver (Department of Civil Engineering and Global Institute for Energy and Environmental Systems, University of North Carolina, Charlotte, North Carolina, USA)
Shi Bin (Department of Earth Science and Advanced Computational Institute for Earth Environment, Nanjing University, Nanjing, China)

Management of Environmental Quality

ISSN: 1477-7835

Publication date: 1 December 2005

Abstract

Purpose

The purpose of this paper is to evaluate the influence of a mixture of nutrient solution, bacteria and biofilm on the consolidation, unconfined compression and desiccation characteristics of two soils that could be used in waste containment applications.

Design/methodology/approach

Experimental work was conducted to investigate the influence of biofilm on the desiccation, strength and consolidation characteristics of two barrier soils. The soils were evaluated with water alone and with a biofilm solution composed of nutrients, bacteria and exopolymeric substances (EPS). These solutions were mixed with a locally available clay (“red bull tallow” (RBT)) as well as a mix of 65 percent sand and 35 percent bentonite (65‐35 Mix).

Findings

Reductions in strength and increases in ductility are observed with biofilm amendment for two soil types. The shear strength was reduced from 413 to 313 kPa and from 198 to 179 kPa for RBT and 65‐35 Mix, respectively. Desiccation tests reveal an increase in moisture retention for early time increments in amended specimens, while both increases and decreases are noted after extended drying. Increases in the rate of consolidation and modest decreases in the compression and swell index were observed. In particular, the consolidation coefficient was increased from 0.036 to 0.064 cm2/min and from 0.060 to 0.093 cm2/min for RBT and 65‐35 Mix, respectively.

Practical implications

These results are useful in establishing the broader impacts of using biofilm as an additive to increase the performance (e.g. reduce hydraulic conductivity and increase resistance to crack formation) of barrier materials in waste containment applications. Moreover, the data provide insight into the geotechnical implications of biofilm‐producing methanotrophic activity that occurs naturally in the covers of municipal solid waste landfills.

Originality/value

Very little research has been published on the influence of biofilm on the behavior of barrier materials in general, and on geotechnical properties in particular. This paper is unique in making the connection between methanotrophic activity, soil modification and barrier material performance.

Keywords

Citation

Daniels, J., Cherukuri, R., Hilger, H., Oliver, J. and Bin, S. (2005), "Engineering behavior of biofilm amended earthen barriers used in waste containment", Management of Environmental Quality, Vol. 16 No. 6, pp. 691-704. https://doi.org/10.1108/14777830510623754

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Publisher

:

Emerald Group Publishing Limited

Copyright © 2005, Emerald Group Publishing Limited

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