Development of the fed-batch bioslurry reactor for the bioremediation of marine sediment contaminated by polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are a toxic environmental pollutant, accumulated usually in marine sediments. Due to the potential hazardous on ecosystem and human, removal of PAHs from sediments has been great concern. In this study, development of ex situ bioremediation technique using fed-batch bioslurry reactor has been conducted for the cleanup of marine sediments polluted by PAHs. Experimental reactor was consisted of original reactor and derivative reactors that were receiving part (1/10 (A) or 1/5 (B) of working volume) of sediment slurry of original reactor after 1 (d1), 2 (d2), and 3 (d3) days incubation. The activity of electron transport system (ETSA) of original reactor was increased from 5.1±0.1 ㎍-O2/㎖/hr after 1 day of incubation to 27.4±0.3 ㎍-O2/㎖/hr after 2-3 days of incubation. ETSA of d2 & d3 reactors was similar to that of original reactor after 2-3 days of incubation. The degradation rate of PAHs was 81.0-92.7% (A) and 85.1-95.4% (B) at d2 & d3 reactors, respectively. The degradation rate of PAHs was increased with the repetition of treatment. The result implies that fed-batch bioslurry reactor was effective for bioremediation of sediments contaminated by PAHs.2

Combinational treatment of UV-C and PAHs degrading bacteria for the remediation of sedimen contaminated with PAHs

To develop the effective and environment friendly remediation method of PAHs contaminated in marine sediment, the degradation rate of BaP and the Microtox toxicity of BaP degrading intermediates were evaluated by the combinatorial treatment of UV-C and BaP degrading bacteria, Novosphingobium pentaromativorans, using artificial sediment based on alumina particles, on which BaP was coated. The degradation rates of BaP treated either by UV-C for one day or by bacterial inoculum for two days, were 59% or 78%, respectively. The toxicities of remaining BaP and degrading intermediates were 32% and 12.5%. To enhance the degradation rate of BaP, UV-C and bacterial degradation were combined. The first microcosm was irradiated by UV-C for one day followed by the bacterial degradation for additional one day and the the second has been incubated with bacteria prior to UV-irradiation. The degradation rates in the two microcosms were increased to 94.2 ~ 99.6% compared to that of inoculation only. Toxicity was also decreased to 22 ~ 23.5% compared to that of 32%, UV-C irradiation only. The toxic intermediates presumably derived from UV treatment can be reduced by bacteria. It could be applicable as one of the effective and environment-friendly methods for the remediation of PAHs contaminated in marine sediment.2

Development of artificial sediment for PAHs bioremediation experiment

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Development of artificial sediment for PAHs bioremediation experiment

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Potential abilities of 2-hydroxypropyl-β-cyclodextrin on the biodegradation of PAH by Novosphingobium pentaromativorans US6-1, isolated from marine environments

Novosphingobium pentaromativorans US6-1, isolated from muddy sediment of Ulsan Bay is able to degrade polycyclic aromatic hydrocarbons. The degradation rate of 5 kinds of PAHs (each 10ppm of pyrene, chrysene, benz[a]anthrathene, benz[b]fluoanthene and benzo[a]pyrene) by strain US6-1 was ranged between 5 and 38% within 7 days when supplemented as a sole sources of carbon and energy. On the other hand PAHs degradation rates were increased to 50~99% when supplied with 10% of 2-hydroxypropyl-β-cyclodextrin (β-HPCD) as an additive. However the individual addition of surfactants (Tween-80, Tritonx-100, Brij 35; each 10xCMC) and/or co-substrates (1%glucose and 1%dextrin) did not enhancing the degradation rate of benzo[a]pyrene except the combination of dextrin and tween-80, degradation rate of this combination was 60%. These evidences imply that degradation of high molecular weight PAHs by strain US6-1 was progressed by cometabolism with appropriate carbon source and enhanced by addition of surfactant. Supplementation of β-HPCD with strain US6-1 was one of the most effective and promisable tools for the bioremediation of high molecular weight PAHs.2

Enhancement of BaP degradation by the combinational treatment of UV-C and benzo[a]pyrene degrading bacteria

To develop the effective and environment-friendly remediation method of PAHs contaminated in marine sediment, the degradation rate of Benzo[a]pyrene (BaP) and the Microtox toxicity of BaP degrading intermediates were evaluated by the combinatorial treatment of UV-C and BaP degrading bacteria, Novosphingobium pentaromativorans, using artificial sediment based on alumina particles coated with BaP. The degradation rates of BaP treated either by UV-C for one day or by bacterial inoculum for two days were 59% or 78% and the toxicities of remaining BaP and degrading intermediates were 32% or 12.5%, respectively. To enhance the degradation rate of BaP, UV-C and bacterial inoculation were combined. The first microcosm was treated by UV-C for one day followed by the inoculum for additional one day, while the second was treated by the reverse order. The degradation rates in these two microcosms were increased to 94.2 ~ 99.6% compared to that (78%) of inoculum only, moreover, the toxicities were reduced from 32% (UV treatment only) to 22 ~ 23.5%. Bacteria might reduce the toxic intermediates presumably derived from UV treatment. However, the survival rate of microorganism after the UV treatment was very low (< 2 cells ml-1) indicating that UV eliminated the bacteria also. These results imply that the sequent treatment of UV and microorganism could enhance the degradation rate of BaP and lower the toxicity through the decomposition of toxic intermediates. It could be applicable as one of the effective and environment-friendly methods for the remediation of PAHs contaminated in marine sediment.1

광양만 퇴적물의 다환방향족탄화수소 오염연구

Polycyclic aromatic hydrocarbons (PAHs) are toxic environmental contaminants and they has hazardous effects on ecosystem or human by its mutagenic and carcinogenic properties. Gwangyang Bay is good candidate in order to understand PAHs distribution owing to many contamination sources. In this study, sediment samples from 11 stations in October 2002 and 2 stations in December 2002 were collected to analyse PAHs concentration. PAHs concentration of 11 stations was in the range from 355 to 61,264 ng/g dry weight (dw). PAHs concentrations in investigated stations were less than 2,500 ppb with the exception of station near the water discharge site of Gwangyang Still Mill Company (SM) and estuary of Woulnae stream (WS) where the PAHs conc. were highest. The major components of PAHs contaminated were high-molecular-weight PAHs that contain more than four aromatic rings (53∼98%). PAHs concentrations in December at the station SM and WS were lower than that of October. It might be the reason of patching effect or dredging. PAHs contamination of Gwangyang Bay were restricted near around the contamination sources.2

Enhancement of PAHs biodegradation in marine sediment

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유류로 오염된 해변 모래의 생물정화기술 적용 연구

해변 모래에 오염된 유류화합물을 대상으로 생물정화기술 적용 가능성을 시험하였다. 영종도 해변에 실험구를 설치하여 70일간 실험을 실시하였다. 현장실험 수행 중 각 시료의 함수율, 무기영양염 농도, 종속영양세균, 유류분해세균,ETS 활성도, CO2 발생량, 석유 탄화수소 농도 변화와 분자생물학적 모니터링방법을 이용한 미생물군집 분석을 함께 수행하였다. 유류 농도는 대조구에 비해지속성 영양염 투여 실험구에서 빠른 감소를 보였으며 미생물이 추가될 경우 초기 분해가 두드러졌다. T-RFLP 방법을 이용하여 접종 미생물을 추적하였을 때투입된 세 종의 미생물을 지시하는 피크가 28일차까지는 존재하다가 70일차에는 검출되지 않았다. 이상의 결과는 생물정화기술이 해변 모래에 오염된 유류제거에 효과적이며 첨가한 제재의 미생물이 원유성분의 감소, 특히 미생물에 의해 쉽게 이용될 수 있는 기질의 농도 감소와 함께 감소함으로써 환경에 지속적인 영향을 미치지 않음을 시사한다.2

The effect of 1,2-hydroxypropyl-b-cyclodextrin(b-HPCD) on biodegradation of high-molecular weight polycyclic aromatic hydrocarbons (PAHs) by strain US6-1

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