Treatment of wood ash containing soluble chromate

The “TA Siedlungsabfall” issued in Germany in May 1993 will entail severe problems concerning the disposal of wood ash. One particular problem is associated with the occurrence of soluble chromium compounds in the leachates of wood ash. During combustion of wood, wood residues or waste wood, Cr-III which is generally found in wood is partly oxidized to Cr-VI. Under the conditions of the leaching test DIN 38 414 part 4, which is the compulsory test procedure according to the “TA Siedlungsabfall”, Cr-VI is partly soluble. Thus, the comparatively low limit value for the leachates is exceeded by many wood ash samples. To achieve significant reduction of the soluble Cr-VI content of wood ash, a procedure termed wet ash removal was applied. Investigations were carried out both under industrial conditions and in the laboratory. It is shown that wood ash leachates with Cr-VI concentrations of up to about 2 mg/l can be treated effectively with this procedure.     

基于改进的高斯混合模型脑ＭＲ图像分割

MR图像中常含有偏移场以及噪声现象,传统的高斯混合模型无法得到正确的分类.在高斯混合模型目标函数中加入偏移场估计与噪声去除,完善其分类效果,使分类结果较好地克服偏移场和噪声影响.实验表明,该算法在得到较准确的分类结果的同时还能很好地估计偏移场.     

EM菌预处理黄姜皂素废水中的应用

本文通过对黄姜废水的水质分析,设计并检验了铁碳微电解-Fenton-絮凝-EM处理方案.主要研究的是EM菌对预处理废水的深度降解,并通过逐一对影响处理效果的的各方面因子等进行了比较分析并讨论了其影响特点.实验结果表明,对于有机黄姜皂素废水,本方案的去除率可以普遍到达98％以上.影响因子分析表明,在温度32℃条件下,EM菌处理预处理废水pH为5左右时,EM投加量为水样的0.7％,处理时间为48h时,处理效果最好.     

Factors affecting soluble selenium removal by a selenate-reducing bacterium Bacillus sp. SF-1

High concentrations of soluble selenium, selenate and selenite, have acute and chronic toxicity toward living things. With the aim of developing a biological process for selenium removal, the effects of a variety of parameters on the reduction of soluble selenium by a Bacillus sp. strain SF-1, which is capable of reductively transforming selenate into selenite and, subsequently, into nontoxic insoluble elemental selenium, were studied. The bacterial strain could effectively reduce 20 mM of selenate to selenite and 2 mM of selenite to elemental selenium in the presence of an appropriate carbon source and in the absence of oxygen. The reduction rate of selenate to selenite was much higher than that of selenite to elemental selenium, resulting in the transient accumulation of selenite during selenate reduction. The selenate reduction rate increased with increases in the selenate concentration up to 20 mM, while the rate of selenite reduction decreased sharply at selenite concentrations of more than 2 mM. The elemental selenium transformed from selenate via selenite was found both inside and outside the cells. Bacillus sp. SF-1 was able to utilize a variety of organic acids or sugars as a carbon source in selenate reduction. Although the copresence of sulfate did not inhibit selenate reduction, it was completely inhibited by some other oxyanions, including nitrate. A model sequencing batch system using the bacterial strain was developed and exhibited good performance in the treatment of wastewater containing high concentrations of selenate.     

Strategies to optimize phosphate removal from industrial anaerobic effluents by magnesium ammonium phosphate (MAP) production

BACKGROUND: Owing to more stringent phosphate discharge requirements and the increasing prices of fertilizers, beneficial recovery and reuse of phosphate from industrial anaerobic effluents is becoming an important issue. Phosphate recovery by struvite or magnesium ammonium phosphate (MAP) permits its recycling in the fertilizer industry because struvite is a valuable slow release fertilizer. Two different approaches to MAP crystallization depending on initial levels of phosphate in the wastewaters were tested and compared. RESULTS: For low‐phosphate‐containing anaerobic effluents (<30 mg PO₄^3?‐P L^?1), a novel approach using ureolytic induced MAP formation with MgO addition appeared to be suitable. The residual phosphate concentrations in the effluent ranged from 5 to 7 mg PO₄^3?‐P L^?1 and the separated matter contained residual amounts of Mg(OH)₂. High‐phosphate‐containing anaerobic effluents (100 to 120 mg PO₄^3?‐P L^?1) were treated efficiently using air stripping combined with MgCl₂ and NaOH reagents, yielding residual phosphate levels of 8 to 15 mg PO₄^3?‐P L^?1 and spherical pure MAP crystals of 0.5 to 2 mm. CONCLUSION: Results show that depending on the initial phosphate concentrations in the wastewaters and the ammonium and magnesium levels, the strategy selected for struvite crystallization is a determinative factor in achieving a cost effective technology. Copyright © 2008 Society of Chemical Industry     

Preparation and analysis of high capacity polysulfone capsules

Since the concept of solvent impregnated resins was introduced in the early 1980s, the technique has been applied to a limited amount of applications. The main disadvantage of the resins was that the amount of solvent inside was limited to approximately 1.5 ml/g polymer. A new generation of solvent impregnated resins is introduced. These capsules can contain up to 11.8 ml solvent/g polymer and were prepared using a modified dry impregnation technique. Due to the high solvent loading, the capacity per volume of capsule for extracting products from aqueous phases is therefore dramatically increased.     

The effect of pH on bioremediation potential for the removal of direct violet textile dye by Aspergillus niger

Alkaline and acidic media have been used in the textile dye industry, depending on the fabric nature. The bioremoval of textile direct violet dye by Aspergillus niger fungal strain was studied. The effect of pH on dye bioremoval was investigated at a pH range from 2 to 11. The direct violet dye bioremoval reached maximum with 92.4%, 64.0%, 91.4%, and 62.3 % at pH values of 2, 3, 8, and 9, respectively, at 24 h of incubation. The percentages of removal rate after 72 h incubation were 98.9, 97.3, 94.0, 95.0, 97.0, and 97.3 at pH 2, 3, 6, 7, 8, and 9, respectively. The optimum pH values were 2, 3, 8, and 9 for direct dye removal. At the end of the experiments, the treatment with fungal strain could reduce COD value of synthetic dye solution by 76-91%. Pseudo first and second order kinetic models were applied to evaluate differences in the biosorption rates and uptakes of textile dye. Pre-equilibrium biosorption of direct violet dye onto fungus under different dye concentrations followed a pseudo second order kinetic model with a high degree of correlation coefficients (R² > 0.99), and the calculated values of q_e nearly matched the experimental values of textile dye during the biotreatment process.     

同时测量氢氧CARS光谱确定火焰温度和氢氧浓度的研究

利用YAG激光器和一台染料激光器同时测量了氢／空气预混平面火焰中氢氧CARS光谱。从氢的S（5）和S（6）支统转动线的强度比获得火焰温度，并与由氮的CARS光谱得到的温度进行了实验校验。氢和氧的浓度分别由氢的S（6）支和氧的Q支光谱求得，并利用红／空气预混平面火焰的局部热力学平衡计算对所得浓度进行了校验。温度的校验误差为4％，而氢氧浓度的校验误差分别为14％和12％。     

两步沉淀法回收铜矿山酸性废水铜资源研究

以德兴铜矿酸性废水为对象,研究了化学硫化两步沉淀法回收矿山酸性废水中铜资源.试验结果表明,溶液pH控制在3.45左右,加入一定量的石灰水,Fe3+优先其它离子沉淀得到去除,去除率可达82％以上；然后在上清液中加入一定量的NaHS与其中的Cu2反应生成CuS沉淀,铜回收率可达99％.