[雙語翻譯]--外文翻譯--在旋轉(zhuǎn)生物接觸器中形成的氧化亞鐵硫桿菌生物膜的性質(zhì)（原文）

1、Biochemical Engineering Journal 12 (2002) 43–48Properties of the biofilm of Thiobacillus ferrooxidans formed in rotating biological contactorL. Nikolov a, D. Karamanev b,?, V. Mamatarkova a, D. Mehochev a, D. Dimitrov aa

2、 Faculty of Biology, Sofia University, 8 Dr. Tsankov Boulevard, 1421 Sofia, Bulgaria b Department of Chemical and Biochemical Engineering, University of Western Ontario London, Ontario, Canada, N6G 5B9Received 3 August 2

3、001; accepted after revision 27 February 2002AbstractThe physico-chemical properties of the Thiobacillus ferrooxidans biofilm formed on the surface of rotating disks in a rotating biological contactor (RBC) were studied

4、under steady-state conditions. The main independent variable was the input substrate (ferrous iron) concentra- tion in the bioreactor. It has been shown that the biofilm thickness was maximal, the biofilm density was min

5、imal and the specific surface area of pores in the biofilm was maximal when the input ferrous iron concentration was between 1 and 2.1 g/l. The biofilm volume remained nearly thesamewheninputsubstrateconcentrationswerebe

6、tween0.49and14.21 g/l,correspondingtooxidationratesbetween0.35and8.6 g/m2 h. © 2002 Elsevier Science B.V. All rights reserved.Keywords: Biofilms; Bioreactors; Kinetic parameters; Thiobacillus ferrooxidans; Iron oxid

7、ation1. IntroductionThe ability of bacterium Thiobacillus ferrooxidans (recently renamed to Acidothiobacillus ferrooxidans) to form biofilms on solids supports has been considered for the development of high performance

8、bioreactors for the needs of metal leaching technologies, purification of gases containing sulfur compounds and acid mine drainage treat- ment [1]. The biofilm itself has been subject of numerous investigations including

9、 its chemical and biological compo- nents [2,3] and interactions with solid supports [4]. How- ever, there is a lack of data about such physico-chemical properties of the biofilm as density, water content and porosity. T

10、hese data could be of interest to bioreactor de- sign as well as for the mathematical model development [5]. The main aim of this work is to reveal the main physico-chemical properties of the biofilm of T. ferroox- idans

11、 as a function of the rate of ferrous iron oxidation, substrate (Fe2+) and product (Fe3+) concentrations.? Corresponding author. Tel.: +1-519-661-2111; fax: +1-519-661-3498. E-mail address: dkaramanev@eng.uwo.ca (D. Kara

12、manev).2. Materials and methods2.1. BioreactorsA laboratory rotating biological contactor (RBC) was used. It has been described in detail previously [6]. It con- sisted of six identical sections of 2.3 l working volume e

13、ach, mounted on a common shaft. This ensured an equal rota- tional speed. Each section contained seven plastic (PVC) disks, 0.2 m in diameter, mounted on the rotating horizontal stainless steel shaft. All the experiments

14、 have been carried out at a rotational speed of 26 rpm. This velocity has been found to be optimal from the point of view of iron oxidation efficiency [7]. Each section was operated independently as an individual bioreac

15、tor (#1–6 in Table 1). The input fer- rous iron concentrations (Table 1) were chosen to cover the range of practical uses of RBCs. After inoculation, the initial biofilm formation was carried out in repeated batch regime

16、 during the first 20 days. The initial substrate concentrations are shown in Table 1. Dur- ing the second step, the bioreactors were switched to con- tinuous operation with a liquid residence time of 400 min (correspondi

17、ng to a dilution rate of 0.15 h?1). The input fer- rous iron concentrations were the same as the initial ones during the batch operation. The liquid temperature was kept1369-703X/02/$ – see front matter © 2002 Elsev

18、ier Science B.V. All rights reserved. PII: S1369-703X(02)00041-4L. Nikolov et al. / Biochemical Engineering Journal 12 (2002) 43–48 45Fig. 2. Effect of iron concentration on biofilm density.The biofilm density (Fig. 2),

19、however, decreased until inlet Fe2+ concentration reached 2.13 g/l, where a local minimum was observed. A further increase in the iron concentration resulted in an increase of biofilm density. Visual observation showed t

20、hat the biofilm was light yel- low in colour at the lowest input substrate concentrations (bioreactors #1–3), and became dark yellow (bioreactor #4), then brown (bioractor #5) and finally, reddish brown (bioreactor #6) a

21、s input concentration increased. Similar biofilm properties were observed by the authors in previ-Fig. 3. Content of iron in biofilm.ous experiments, including these using inverse fluidized bed bioreactor. The colours in

22、 each bioreactor remained the same during a 6-month operation of the bioreactor [6]. The formation of slime (probably, extracellular polysac- charides) was also observed visually. The slime formation was observed only in

23、 the bioreactors with the input ferrous iron concentrations between 0.49 and 2.13 g/l (bioreac- tors #1–3). Very small formation of slime was observed in bioreactor #4, while no slime was visibly detected in bioreactors