难处理金矿石中硫化物细菌氧化的活性序列

通过显微镜观察难处理金矿石中硫化物矿物对的细菌氧化过程 ,以硫化物矿物对的显微电池模式为基础 ,得出硫化矿物细菌氧化的活性系列。难处理金矿石中常见矿物细菌氧化活性序列由强至弱依次为

硫化物氧化及新工艺

综述了丝状硫细菌、光合硫细菌和无色硫细菌 3类氧化硫化物为单质硫的微生物的生理特征与产硫条件 ,以及国内外利用其进行生物脱硫工艺的研究现状 ,指出无色硫细菌体外排硫、氧化硫的效率高 ,每增长 1g细菌细胞至少可产生 2 0 g单质硫 ,更适合于工业化的生物脱硫工艺 .同时总结了生物脱硫新工艺的重要标准和今后研究与应用的方向 ;总结了国内外从酶学和遗传学角度研究生物脱硫过程的分子机理 。

虾池底质中NH_4^+-N、S^(2-)和异养细菌含量的变化及其相关性研究

随着养殖进程，底质中NH＋4-N、S2-和异养细菌的含量一直呈升高之势，其变化主要受控于底质中有机质含量的多寡，水温只是其影响因素之一。虾池底质中NH＋4-N、S2-和异养细菌的含量分布：沟泥＞滩泥＞池水，异养细菌和NH＋4-N、S2-含量呈正相关。文中对改善虾池底质环境，降低底质中NH＋4N。

舌苔微生物在口臭中的作用

舌背微生物群是人体生态学中最复杂的系统之一,但有关舌背微生物群对健康和疾病的影响却知之甚少,舌苔的组成及其影响因素大部分不为人知。近年来的研究证实,口臭与挥发性硫化物、丙酸、丁酸、尸胺、腐胺、吲哚和粪臭素等,特别是与硫化氢和甲硫醇的关系十分密切,而舌背的诸多明确或未明确的甚至特异的微生物与这些口臭物质关系密切。通过刷牙、刷舌和刮舌等机械清除法控制舌苔,联合应用抗菌药物控制舌背微生物群,或者机械清除和药物治疗相结合可以有效减轻口臭。本文就舌苔的微生态环境、舌苔细菌与口臭和舌苔的控制与口臭等研究进展作一综述。

Identical carbon isotope trends of carbonate and organic carbon and their environmental significance from the Changhsingian (end-Permian), Meishan, South China

High resolution carbon isotope analyses of carbonate and organic carbon from Meishan, South China showed that the variation of δ13Ccarb is marked by three large positive excursions during the Changhsingian (end-Permian). Carbon isotope stratigraphy during this stage shows three cyclic intervals in δ13Ccarb, with two cycles corresponding to the lower (Paleofusulinid minima Zone) and one corresponding to the upper Changhsingian (P. sinensis Zone). The large positive δ13Ccarb excursions indicate episodes of enhanced burial of isotopically light or-ganic carbon, presumably in response to deep-water anoxia episodically extending into shallow water with the rise of sea level. The organic carbon during the Changhsingian is distinguished into two groups, and the δ13Corg of each group parallels (separately) the more detailed profile of δ13Ccarb, strongly showing that the values of fractionation Δ13Ccab-org remain relatively constant, with only two intervals with anomaly. The enhanced fractionation Δ13Ccab-org with large negative δ13Corg excursions apparently indicates significant inputs from sulfide-oxidizing bacteria and green sulfur bacteria, notably at bed 24 just predating mass extinction. Our evidence appears to support that the ex-tended euxinic water is possible for the main pulse of mass extinction at the end-Permian.

Bacterial oxidation activity in heap leaching

Bioleaching of sulfide minerals by bacteria, mainly Thiobacillus ferrooxidans(T.f.) and Thiobacillus thiooxidans, plays an important role in hydrometallurgy because of its economic and environmental attractions. The surveys of production process and the bacterial oxidation activity in the heap bioleaching were investigated. The results show that pH value is high, bacteria biomass and ferric concentration are low, generation time (above 7.13 h) is long in leachate, and less bacteria are adsorbed on the ores. The bacteria in the leachate exposing on the surface and connecting with mineral, have much faster oxidation rate of Fe(Ⅱ) and shorter generation time, compared with those which are in the reservoir for a long time. There is diversity for oxidation activity of Fe(Ⅱ), while there is no diversity for oxidation of sulfur. So it is advisable to add sulfuric acid to degrade pH value to 2.0, add nutrients and shorten recycling time of leachate, so as to enhance bacteria concentration of leachate and the leaching efficiency.

Acidophilic bacterial community reflecting pollution level of sulphide mine impacted by acid mine drainage

To reveal the impact of mining on bacterial ecology around mining area,bacterial community and geochemical characteristics about Dabaoshan Mine(Guangdong Province,China)were studied.By amplified ribosomal DNA restriction analysis and phylogenetic analysis,it is found that mining pollution greatly impacts the bacterial ecology and makes the habitat type of polluted environments close to acid mine drainage(AMD)ecology.The polluted environment is acidified so greatly that neutrophil and alkaliphilic microbes are massively dead and decomposed.It provided organic matters that can make Acidiphilium sp.rapidly grow and become the most bacterial species in this niche.Furthermore,Acidithiobacillus ferrooxidans and Leptospirillum sp.are also present in this niche.The amount of Leptospirillum sp.is far more than that of Acidithiobacillus ferrooxidans,which indicates that the concentration of toxic ions is very high.The conclusions of biogeochemical analysis and microbiological monitor are identical. Moreover,because the growth of Acidithiobacillus ferrooxidans and Leptospirillum sp.depends on ferrous iron or inorganic redox sulfur compounds which can be supplied by continual AMD,their presence indicates that AMD still flows into the site.And the area is closer to the outfalls of AMD,their biomasses would be more.So the distinction of their biomasses among different areas can help us to find the effluent route of AMD.

Influence of sulfur addition/solids content ratio on removal of heavy metals from mine tailings by bioleaching

The effect of sulfur addition/solids content(SA/SC)ratio on heavy metals(e.g.copper,zinc and lead)obtained from mine tailings by indigenous sulfur-oxidizing bacteria was studied,and the changes in the chemical forms of heavy metals after bioleaching were explored.The results show that the solubilization of metals is significantly influenced by SA/SC ratio,and SA/SC ratio of 2.50 is found to be the best for bacterial activity and metal solubilization among six SA/SC ratios tested(such as 1.00,1.33,1.50,1.67,2.00 and 2.50)under the chosen experimental conditions.The pH decreases fast and the maximum solubilizations of copper and zinc are respectively 81.76% and 84.35% while that of lead only reaches 40.36%.After bioleaching,the chemical forms of heavy metals have changed.The metals remained in mine tailings are mainly found in residual fractions,which is harmless to the surrounding environment.

Bioleaching of low-grade copper sulfide ores by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans

The grown conditions of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were investigated,and then experiments were conducted to research the bioleaching behaviors of crude ore of copper sulfide and hand-picked concentrates of chalcopyrite by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans.The experimental results show that the bacteria grow best when the temperature is(30±1) °C and the pH value is 2.0.The bacteria concentration is 2.24×107 mL-1 in this condition.It is found that the copper extraction yield is affected by the inoculum size and the pulp density and the extraction yield increases as the inoculum size grows.The bioleaching rates reach their highest point in sulfide copper and chalcopyrite with a pulp density of 5% and 10%,respectively.Column flotation experiments of low-grade copper sulfide ores show that the bioleaching recovery reaches nearly 45% after 75 days.

An experimental study of pyrite bio-leaching as a way to control spontaneous combustion

Bio-leaching of pyrite by native strains of acidophilic bacteria was examined by laboratory scale tests. Three groups of batch trials in agitated flasks and three continuous column leaching tests were performed. The leaching ability and efficiency of native bacteria was greatly improved by adaptation of the bacteria to the test conditions. These cultivated bacteria were then used for the leaching process. The changes in solution pH, Eh, Fe2~ concentration, and sulfate ion concentration were monitored throughout the tests. A portion of the pyritic sulfur is transformed into soluble sulfate ion. The desulfur- ization ratio of＇42.6g was obtained in a flask shaking test and a ratio of 39.4g was obtained during column leaching. A weight gain test was performed on leached and unleached samples by exposing the samples to humid air for several days. A smaller weight gain of the bio-leached samples indicates that removing sulfur from the sulphide ore helps reduce its oxidation rate and the potential for spontaneous combustion.

Investigation of mortar corrosion by an acidophilic sulfur-oxidizing microorganism A.thiooxidans

The corrosion behavior of the acidophilic sulfur-oxidizing microorganism(ASOM)Acidithiobacillusthiooxidans(A.thiooxidans)on mortar was investigated for changes of medium and mortar,as well as for weight lossand surface morphology of mortar specimens.Weight loss analysis showed that mortar weight was reduced by(15.1±2.2)%after 56 d.Morphological surface analysis of mortar specimens showed weakly structured fibrous substances with2−100μm in size.The pH variations of the mortar surface and medium indicated that biogenic sulfuric acid had beenproduced by A.thiooxidans.The results prove that A.thiooxidans accelerated concrete corrosion and caused concretefailure.

Performance of biotrickling filters for hydrogen sulfide removal under starvation and shock loads conditions

In the industrial operation of biotrickling filters for hydrogen sulfide(H2S) removal,shock loads or starvation was common due to process variations or equipment malfunctions.In this study,effects of starvation and shock loads on the performance of biotrickling filters for H2S removal were investigated.Four experiments were conducted to evaluate the changes of biomass and viable bacteria numbers in the biotrickling filters during a 24-d starvation.Compared to biomass,viable bacteria numbers decreased significantly during the starvation,especially when airflow was maintained in the absence of spray liquid.During the subsequent re-acclimation,all the bioreactors could resume high removal efficiencies within 4 d regardless of the previous starvation conditions.The results show that the re-acclimation time,in the case of biotrickling filters for H2S removal,is mainly controlled by viable H2S oxidizing bacteria numbers.On the other hand,the biotrickling filters can protect against shock loads in inlet fluctuating H2S concentration after resuming normal operation.When the biotrickling filters were supplied with H2S at an input of lower than 1700 mg/m3,their removal efficiencies were nearly 98% regardless of previous H2S input.