Inhibition of acid rock drainage from uranium ore waste using a conventional neutralization and precipitation treatment

Glass columns (length 50 cm, i.d. 4 cm) containing 900 g of uranium ore waste were subjected to a three-step process: (1) acid drainage generation, (2) neutralization and precipitation treatment and, again, (3) acid drainage generation. In the first acid generation step, lasting about one year, different variables (pyrite addition, inoculation and irrigation solution) were tested by measuring effluent pH, redox potential, total iron and sulphate. Conditions of acid generation were satisfactorily reproduced, reaching stable pH values around 2.0 that were determined mainly by pyrite addition and the type of irrigation solution used (distilled water or ferrous sulphate). The neutralization and precipitation treatment consisted of alternating irrigations of a neutralizing solution (CaO saturated plus NaOH) and a precipitating solution (ferric sulphate saturated). This treatment caused accumulation of basic iron sulphate and iron oxide precipitates according to SEM studies. After this treatment, the barrier effect created by the reaction products was checked, using irrigation solutions similar to the first step. The effluents collected showed higher pH and lower redox potential, total iron and sulphate values than those observed before the treatment, evidencing inhibition of acid drainage generation.     

井下原地溶浸技术试验研究

结合东同矿业公司井下原地溶浸的试验研究情况,分析了细菌浸出-萃取-电积工艺过程中存在的问题并提出了解决方法,探讨了该工艺应用研究的发展方向与前景。     

Toxicity Estimation of Phenolic Compounds by Bioluminescent Bacterium

Phenolic compounds are environmentally important due to their extensive use in various industries, presence in wastewaters, and potential toxicity. When phenolic compounds reach the activated sludge processes of publicly owned treatment works, they can cause upsets in the operations of the treatment plants. A continuous toxicity testing system was developed based on the bioluminescent bacterium Shk1. The toxicities of 23 phenolic compounds to Shk1 were studied and the 5 min EC50 values were obtained. Quantitative structure-activity relationship models based on the logarithm of the octanol-water partitioning coefficient [log(Kow)] were established for estimating the toxicity of phenolic compounds and the model validity was verified.     

High-pressure-induced changes in bovine milk: a review

High-pressure (HP) treatment of food products is a novel processing technique during which the product is treated in a vessel of suitable strength at a high pressure, generally in the range 100–1000 MPa. As a result, several constituents and properties of the treated product are altered. HP-induced changes in the constituents and properties of milk are arguably among the most extensive of the range of food products studied to date. HP treatment of milk induces solubilization of minerals associated with the casein micelles, denatures whey proteins and, depending on pressure, can either induce aggregation or disruption of the casein micelles. These HP-induced changes in milk constituents affect the properties of the milk; cheesemaking properties of milk can be enhanced considerably, indicating potential application of HP treatment in this area; furthermore, encouraging results have also been reported for HP treatment of milk prior to yogurt manufacture. HP treatment of milk also affects its microflora; however, considerable variation in baroresistance between bacterial species and strains exists. Further applied research appears warranted to establish the full commercial potential of HP treatment of milk.     

Ozone Contribution in Food Industry in Japan

Ozone has the strongest oxidization effect after fluorine, and this property has been used in sterilization for food and processing plants in Japan. Moreover, there is no fear of toxic residues as with chlorine-based sterilizers and no hazardous trihalomethanes are formed. Based on these advantages, ozone has been used in water and air treatment for food products food materials and food processing plants. Use in the food processing is now increasing in Japan. This paper describes ozone sterilization, introducing sterilization systems and equipment applied to food in Japan.     

Diffusivity of bacteria

The effects of motility and aggregation on the diffusion coefficient for bacteria were studied in an aqueous system. The effects of cell concentrations, capillary tube sizes, and dilution rates on the diffusion coefficient were examined. In general, motile cells can diffuse about 1000 times faster than non-motile cells.Pseudomonas aeruginosa, a motile cell, andKlebsiella pneumoniae, a non-motile cell, were used for this research. Diffusion coefficients were measured by the capillary tube assay developed by Adler [1969]. From this procedure the diffusion coefficient ofPseudomonas aeruginosa was 2.1×10⁻⁵ (standard deviation: 1.0× 10⁻⁵) cm²/s and that ofKlebsiella pneumoniae was 0.9×10⁻⁵ (standard deviation : 0.5 × 10⁻⁵) cm²/s. The diffusion coefficient ofPseudomonas aeruginosa was about 2.3 times higher than that ofKlebsiella pneumoniae. The Stokes-Einstein equation could not be used for estimating the diffusion coefficients forKlebsiella pneumoniae andPseudomonas aeruginosa. The experimental value for the diffusion coefficient ofKlebsiella pneumoniae was about 2000 times higher than that (4.5×10⁻⁹ cm₂/s) obtained from the Stokes-Einstein equation. This discrepancy was due to the aggregation ofKlebsiella pneumoniae.     

Ozone in the Laundry Industry—Practical Experiences in the United Kingdom

Since the early 1990s, the use of ozone in many commercial and industrial laundering applications has been evolving rapidly. Ozone allows washing to be conducted using cold water, thereby saving considerable heat energy and water consumption. Additionally, ozone enhances the wash process, resulting in a significant reduction in detergent dosage and number of rinses, thus saving water. Ozone/cold water cycles are gentler to fabrics, thus extending linen life. Finally, ozone/cold water laundering is beneficial for effluents, resulting in reductions in COD (chemical oxygen demand). Microorganisms are destroyed effectively in ozone-wash waters, and washing and drying cycles are shorter, thus saving labor. In this paper, the authors describe some specific case studies at commercial laundering installations in the UK, whereby the users of ozone have reaped major benefits, including enhanced microorganism kills/inactivation and significant cost savings.     

关于氨厂循环水加氯杀菌规律的探索

根据我公司循环冷却水系统1998年11月至1999年4月期间水中余氯异常的现象,和水中NO 2、NH4 含量、pH值等因素对余氯和菌藻的影响,论述了氨厂循环水加氯杀菌规律,同时强调了循环水系统运行管理的重要性。     

微生物发酵生产2,3-丁二酮的研究

2,3-丁二酮又称双乙酰,是一种黄色至浅绿色具有强烈奶油香味的重要香料。2,3-丁二酮传统上用合成法生产,我们以农副产品为主要原料,利用选育的高产菌株发酵生产,发酵工艺条件温和,产品风味自然、逼真、安全性高,视同天然产品,符合人们崇尚自然的趋势,可广泛用于食品、日化、饲料香精的生产。     

循环冷却水中微生物对黄铜管的腐蚀影响

采用交流阻抗(EIS)测试技术，研究了电厂循环冷却水中微生物对黄铜腐蚀行为影响。结果表明黄铜电极在有菌培养基溶液中浸泡初期，电极表面形成的生物膜抑制了黄铜的腐蚀，随着浸泡时间的延长，生物膜内微生物的代谢活动和代谢产物促进了黄铜的腐蚀。提出了在无菌和有菌培养基溶液中所测得的EIS的等效电路，并计算了相应的等效电路参数。