S40 Special Abstracts / Journal of Biotechnology 150S (2010) S1–S576

[E.16]

Biotransformation and biodegradation processes in sedimentcaps

D. Reible 1,2,∗, T. Smith 1,2, F. Yan 1,2, L. Katz 1,2, M.J. Kirisits 1,2

1 Environmental and Water Resources, Department of Civil, Architec-tural and Environmental Engineering, University of Texas at Austin2 Nathan Johnson, Department of Civil Engineering, University ofMinne, United States

Conventional sediment caps are typically composed of sandymaterials and are designed to physically contain contaminated sed-iment and separate contaminants from benthic organisms. Eventhese simple caps, however, trigger changes in the biogeochemi-cal conditions beneath a cap that can affect the fate and transportbehaviour of contaminants. In addition, caps can themselves serveas biological reactors encouraging biotransformation and biodegra-dation of contaminants that migrate from the underlying sediment.Finally, there are means of modifying the microbial environmentand the resulting biotranformation and biodegradation processes.

The effect of a cap on the underlying sediment biogeochemicalprocesses will be reviewed with an emphasis on the implicationsfor contaminant fate and transport behaviour. Of particular concernis the potential impact on mercury methylation processes. Drivingthe sediment underlying a cap to more reduced conditions couldincrease methylation and result in greater mobility of the mercurycontamination. Laboratory experiments will be described to assessmercury behaviour.

The dynamics and characteristics of the microbial communitiesthat develop within a sediment cap will also be summarized withimplications for degradation of sediment contaminants migratinginto the cap. Because much of a cap will exhibit reduced condi-tions, many sediment contaminants may not degrade significantly.Currently, we are investigating manipulating the biological com-munity with low power electrodes to create or expand oxidizingor reducing regions. The approach employs low cost graphite clothelectrodes placed horizontally with the sediment cap. Low volt-ages (2–4 V) and minimal currents are used to produce the desiredchanges in redox environment and create zones conducive tomicrobial transformation or degradation of contaminants. Novelaspects of the approach are the low power requirements and theuse of low cost electrode materials that are long lived and influencethe redox conditions over large areas. The potential and limitationsof this approach will be summarized.

doi:10.1016/j.jbiotec.2010.08.112

[E.17]

A Case Study of Passive Bioremediation of ContaminatedGroundwater using River Sediment as Microbial Barrier

A. Katayama 1,2,∗, F.M. Liu 1, I. Suzuki 2, N. Yoshida 1, K. Asahi 3

1 EcoTopia Science Institute, Naogya University, Japan2 Graduate School of Engineering, Nagoya University, Japan3 Environmental Science Institute of Nagoya City, JapanKeywords: Natural attenuation; Dechlorinating bacteria; Ground-water contamination; Site characterization

Natural attenuation, one of passive bioremediation technolo-gies, has attracted attentions because of its low cost and minimalenergy requirement. In a contaminated site, where groundwatercontaminated with chlorinated solvents (1,2-dichloroethane, 1,2-cis-dichloroethelene, etc has been flown into river through the riverbed, we have conducted a case study to characterize the site and

to examine the potential of bioremediation of the contaminatedgroundwater using river sediment as microbial barrier, as one ofnatural attenuation method.

The hydrological and physiochemical characterizations of thecontaminated site were carried out to examine the potential ofbioremediation using the river sediment as microbial barrier. Theriver sediment was also examined in the dechlorination path-ways of chlorinated solvents, the degradation rate under differenttemperature, and the dechlorinating microbial populations in thelaboratory.

The contaminated groundwater was estimated to flow throughthe river sediment with a retention time of 50days. Moderatedechlorination potential was suggested by the physico-chemicalcharacterization of the sediment. Chlorinated solvents werefound microbiologically dechlorinated to ethylene by the reac-tions of reductive dechlorination and dichloroelimination. The16S-rRNA gene-targeting polymerase chain reactions suggestedthe presence of dechlorinating bacteria, Dehalococcoides andDehalobacter, in the sediment. The dechlorination activitiesdecreased with the decrease in temperature, but the activitiesat 18 ◦C of groundwater temperature were still high enough todecrease the concentrations of chlorinated solvents lower thanthose of the environmental standard, except for the case of1,2-dichloroethane.

The results suggested that the anaerobic microorganisms inthe sediment had a high potential to remediate the groundwa-ter contaminated with chlorinated solvents to prevent the riverfrom the contamination, except for 1,2-dichloroethane. Furtherstudy is being carried out for the enhanced attenuation for 1,2-dichloroethane.

doi:10.1016/j.jbiotec.2010.08.113

[E.18]

Waste gas treatment in the pulp and paper industry: A compar-ison of reactor performance

M.E. López ∗, E. Rene, M.C. Veiga, C. Kennes

University of La Coruna, SpainKeywords: Biotrickling filter (BTF); biofilter (BF); Eliminationcapacity (EC); Candida boidinii; Rhodococcus strain; Ophiostomastenoceras sp.; Autotrophic bacteria; Pulp and paper industry;Hydrogen sulphide; Methanol; Pinene

Introduction: Pulp, paper and wood-related industries producetoxic air-pollutants like H2S, �-pinene and methanol, which appearat different stages of processing/manufacturing (Kennes and Veiga,2001). In order to efficiently handle this pollutant mixture, both atwo-stage bioreactor (BTF→BF) and a single-stage BTF were oper-ated separately and their performance was compared.

Methods: Inoculum: In the two-stage bioreactor, the first-stage BTF was inoculated with a mixture of an autotrophicH2S–degrading culture and an acid-tolerant methanol degrad-ing yeast (Candida boidinii), while an Ophiostoma stenoceras sp.,was used to inoculate the second-stage BF (Rene et al., 2010).In the second experiment, with the one-stage BTF, a mixture ofthe above mentioned consortium and a Rhodococcus strain wasadded.

Filter bed: The BTFs were packed with pall rings, while the BFwas packed with a mixture of perlite and pall rings.

The EBRTs used in the two-stage bioreactor were 83.4, 41.7,27.8 s in the BTF, 146.4, 73.2, 48.8 s in the BF, and in the one-stageBTF, EBRTs of 38 and 26 s were used.

Results and Discussion: Two-stage bioreactor: H2S and methanolwere better removed in the first stage (BTF) with ECs of 45