Papers by Author: Jian She Liu

Abstract: In allusion to Cr³⁺s toxic effect on activated sludge in SBR process system, by determination of the Cr³⁺ adsorption rate, mlvss under different initial SVIs and different chromium loads, the Cr³⁺s toxic effect on activated sludge and the Cr³⁺s influence on chromium adsorption of activated sludge were studied. The research shows that within tolerance range, the activated sludge of SBR system can adsorb 60% chromium ion within 10min reaction. Moreover, with the increase of chromium load, the final chromium remnant rate decreases; within tolerance range, the increase of chromium load contributes to the adsorption of chromium ion and the acceleration is subject to initial SVI. Within non-tolerance range, the ability of SBR process system to adsorb chromium decreases greatly; The whole curve of chromium remnant rate shifts upward with the increase of chromium load level. Within 10mins reaction, the adsorption rate of chromium is about 50% under best condition.

Abstract: Aiming at the toxic effect of Cr³⁺ on the activated sludge in sequencing batch reactor (SBR) process system, the article researched the toxic effect of Cr³⁺ on activated sludge and sewage processing in SBR process system through detecting the COD changes of SBR activated sludge with different chromium loads and different initial SVIs. The results show that when chromium load level is lower than 12.5mgCr³⁺/g mlvss, Cr³⁺ can promote activated sludge to adsorb organic substance COD. The effect is affected by the initial SVI which exerts impact on the toxic effect of chromium load on activated sludge within the tolerance range. When it is within the non-tolerance range, the final effluent COD of the system increase apparently. In the process, COD change curve is rather gentle; and the time of arriving at a rather low COD is relatively delayed. The system tolerance of chrome toxicity with a low initial SVI is comparatively strong.

Abstract: Bacterial preoxidation of refractory gold ore has showed many advantages, such as lower operation cost and environmental friendly. In this paper, biooxidation of refractory gold ore by mixed moderate thermophiles culture in airlift bioreactor has been well studied. Firstly, a laboratory scale airlift bioreactor unit has been designed for bacterial preoxidation of refractory gold ore, a mixed moderate thermophilic culture was incubated. The orthogonal experiment was performed to investigate the effects of particle size, pulp density, aeration rate and initial pH. The results showed that when particle size 37micrometer，pulp density 5%，aeration rate 4 dm3•s-1 and initial pH 1.2, the arsenic leaching rate achieved to 93.5%. On the base of the airlift bioreactor unit, a continuous airlift bioreactor was designed. The preoxidation of refractory gold ore by a mixed culture of moderately thermophilic bacteria also was investigated in this equipment. The results showed that, under the conditions of pulp density 8% and stay time 60h, it can deal with 0.256 kg refractory gold ore per day, and the arsenic leaching rate can reach to 95.25%. During the experiment, some leaching liquor has been sampled from the second sect the fourth column of the continuous airlift bioreactor. The composition of microbial communities in this sample has been investigated using culture-independent 16S rDNA based cloning approach- restriction fragment length polymorphism. The phylogenetic analysis revealed that Leptospirillum ferriphilum and Acidithiobacillus caldus are the main organisms in this system. Both of them are moderate thermphilic bacteria and can resist relatively high concentration of arsenic ion.

Abstract: The composition of microbial communities in five acid mine water samples were studied, using culture-independent 16S rDNA based cloning and restriction fragment length polymorphism (RFLP) analysis. Phylogenetic analysis revealed that the bacteria in these five samples fell into 4 major groups: Proteobacteria, Nitrospira, Firmicutes and Bacteroidetes. Proteobacteria organisms such as A. ferrooxidans appeared in samples SX3, K1 and K2, but was scarce in samples SX1 and SX2; Nitrospira organisms Leptospirillum ferrooxidans, Leptospirillum ferriphilum and Leptospirillum group III, were prevalent in samples SX1, K1 and K2, but with fewer in samples SX2 and SX3. Archaea were only detected in samples K1 and K2 from the Tong shankou copper mine. Thermoplasma and Ferroplasma lineages were detected abundantly in these two samples. Meanwhile, the results of Principal Component Analysis (PCA) based on the percentages of OTUs and data of biogeochemical parameters, revealed that biogeochemical properties affected the diversity of microbial communities in mine water. The pH, temperature and different concentrations of elements such as S, Ni, Co and Cu seemed to be key factors resulting in the diverse distribution of microbes.

Abstract: The highly conserved operon iron–sulfur cluster (iscSUA) is essential for the general biogenesis and transfer of iron–sulfur proteins in bacteria. In this study, expression, purification and characterization of the proteins of the isc operon (iscSUA) of Acidithiobacillus ferrooxidans ATCC 23270 was studied. Assembly and transfer of [Fe4S4] in vitro during the isc proteins and other iron sulfur proteins was studied in order to detect the pathway and mechanism of [Fe4S4] assembly and transfer in vivo. The [Fe4S4] cluster was successfully assembled in iron-sulfur proteins in vitro in the presence of Fe2+ and sulfide, and it was successfully transferred from IscA or IscU to iron- sulfur proteins. Our results support and extend certain models of iron-sulfur clusters assembly and transfer.

Abstract: The acidophilic heterotrophic bacteria Acidiphilium spp. were considered as a ministrant of Leptospirillum spp., Acidithiobacillus spp. and other autotrophic bacteria in acid mine drainage (AMD). 25 Acidiphilium-like bacterial strains were isolated from eight different mines in China and their physiology was characterized. Their marmatite-bioleaching ability has been investigated and compared with that of a mixed culture of Acidiphilium sp. and Acidithiobacillus ferrooxidans. The results indicated that some Acidiphilium-like strains exhibited a high marmatite-bioleaching ability, which was even higher than that of Acidithiobacillus ferrooxidans. The leaching efficiency was not higher in mixed than in pure culture. The phylogenetic relationship of the 25 Acidiphilium-like strains was analyzed by 16S rRNA sequencing, GyrB sequencing and rep-PCR genomic fingerprinting. The 25 strains and other eight species of Acidiphilium spp. were clustered into three groups.