The photodegradation of metronidazole in the presence of coexisting pharmaceuticals

The objective of this study was to investigate if coexisting compounds could affect the fate of pharmaceuticals in surface water under solar irradiation. The degradation of metronidazole (MET) in the presence of different coexisting pharmaceuticals was investigated in batch experiments with exposure to sunlight. Tinidazole, which has a similar structure to MET, was employed as an analogue. The results indicated that the presence of an analogue with a similar photosensitive group to MET could inhibit the photodegradation of MET. In addition, the effect of coexisting pharmaceuticals with different absorption spectra on the degradation of MET was investigated. The results showed that the effect depended on the degree of overlapping absorption spectra between MET and the coexisting pharmaceuticals. The relationship between the degree of the influence and the ultraviolet absorption spectra of coexisting pharmaceuticals found in this study could give guidance in assessing the fate of pharmaceuticals in environmental water.     

Optimization of the removal of phenol by soybean seed coats using response surface methodology

Peroxidase from soybean seed coats catalyzes the oxidation and polymerization of aromatic compounds in the presence of H(2)O(2). The present study investigated the optimization of the phenol removal from wastewaters by direct using of soybean seed coats that can be extended to large scale, as a cost-effective option in comparison to pure enzyme. A central composite design was used to evaluate the effect of the following factors on the phenol removal: H(2)O(2) concentration (1-40 mmol/L), polyethylene glycol (PEG) concentration (0-1 g/L) and the amount of soybean seed coats (10-60 g/L). The results showed that PEG concentration had no significant effect on phenol conversion. Additionally, by increasing the amount of soybean seed coats, the extent of phenol conversion was increased and a higher concentration of H(2)O(2) was required to reach the maximum phenol conversion. Under optimum conditions for 1 mmol/L initial phenol, 50 g/L soybean seed coats, 14 mmol/L H(2)O(2) and 0.8 g/L PEG, the phenol conversion after 30 min was 78%. After 2 h, the catalyzed process was capable of achieving 90-92% removal of the total phenol from synthetic wastewater. A cubic model was also developed that was verified by predicting some independent experimental results.     

Regeneration of barium carbonate from barium sulphide in a pilot-scale bubbling column reactor and utilization for acid mine drainage

Batch regeneration of barium carbonate (BaCO(3)) from barium sulphide (BaS) slurries by passing CO(2) gas into a pilot-scale bubbling column reactor under ambient conditions was used to assess the technical feasibility of BaCO(3) recovery in the Alkali Barium Calcium (ABC) desalination process and its use for sulphate removal from high sulphate Acid Mine Drainage (AMD). The effect of key process parameters, such as BaS slurry concentration and CO(2) flow rate on the carbonation, as well as the extent of sulphate removal from AMD using the recovered BaCO(3) were investigated. It was observed that the carbonation reaction rate for BaCO(3) regeneration in a bubbling column reactor significantly increased with increase in carbon dioxide (CO(2)) flow rate whereas the BaS slurry content within the range 5-10% slurry content did not significantly affect the carbonation rate. The CO(2) flow rate also had an impact on the BaCO(3) morphology. The BaCO(3) recovered from the pilot-scale bubbling column reactor demonstrated effective sulphate removal ability during AMD treatment compared with commercial BaCO(3).     

Disruption of Synechocystis PCC 6803 for lipid extraction

In order to extract intracellular lipids from cyanobacterial Synechocystis PCC 6803 for biofuel production, seven cell-disruption methods - autoclaving, bead beating, freeze drying, French press, microwave, pulsed electric fields (PEF), and ultrasound - were tested prior to lipid extraction to make intracellular lipids more accessible by organic solvents. The different methods brought about distinct disruption effects to the cell envelope, plasma membrane, and thylakoid membranes that were related to extraction efficiency. Microwave, PEF, and ultrasound with temperature control had significant enhancement of lipid extraction (9-13% increases). Bead beating, freeze drying, and French press did not provide significant enhancement of lipid extraction. Furthermore, autoclaving, French press, and ultrasound treatments caused significant release of lipid into the medium, which may increase solvent usage and make medium recycling difficult. In order to minimize the cost of cell-disruption and lipid-extraction steps, microwave and PEF (with temperature control) might be best suited for large-scale cell disruption among all techniques investigated.     

用于水质保护的排水管理措施

排水有助于改善路况,降低公共健康风险,实现农作物高产稳产,减少地表径流侵蚀,增加土地价值.农业排水包括人工地下排水和地表排水.农业排水系统正逐渐成为污染物的输送管道,特别是营养物污染.探讨了排水水质保护措施,包括排水系统设计、控制排水、植被缓冲过滤带、侧进控制、反应墙和农业管理等.     

盐的某些神秘功能

除了调节身体的水量之外,盐还有其他许多重要功能。盐是一种强效的天然抗组胺剂,它可以缓解和消除哮喘症。在喝完一杯或两杯水后,把盐放到舌头上,它就和呼吸器一样有效,而且不会产生毒性。盐的这种使用方式,只适用于因干渴而处于危机状态的身体。在通常情况下,你应该把盐放到食物或水中。     

非洲主要河流的潜在作用

讨论了非洲几大水系在满足当地水资源和能源需求方面所起的主要作用。预计在21世纪末,低廉的水力发电或蓄能可以满足非洲大部分的能源需求。对非洲主要大型河流刚果河、赞比西亚河、尼日尔河及尼罗河的水电蕴藏量及其开发利用状况与产生的效益,开发过程中面临的诸多困难及应对措施等作了介绍。     

Women and food aid: a developmental perspective

The unique aspect of food aid projects is that food, rather than money, is used for achieving developmental objectives. As food is usually controlled by women, they benefit most from considering it to be of economic value. Poor women seem to be short of resources--time and money--which can be supplemented by food aid. Through its income-transfer effect, food aid can enable women to work fewer hours/day and thus have more discretionary time. It can also provide, directly or indirectly, the cash necessary for women to use skills they already possess to set themselves up in small businesses. Food aid projects achieve their developmental objectives through: the nutritional content of the distributed commodity; the income transfer effect; cooperatives or associations; specific activities associated with the project; community improvement aspects resulting from the project; and provision of budgetary support to release resources for additional developmental activities. There are a number of ways through which food aid exerts its effect on women from a developmental perspective. Consumption of the food aid commodity provides women with an improved diet. Food aid as an income transfer can enable women to have more discretionary time. Providing women with opportunities for income-generating activities is an important aspect of development. Women's cooperatives or associations funded by food aid commodities can provide women with income. Current food aid projects, if properly planned, can be beneficial to women without the incorporation of specific activities or skills training. One way that food aid helps women gain more time is by freeing them from wage employment. Another way is to use the income transfer for the purchasing of consumer goods that reduce their labor.     

NUMERICAL MODELING OF SUSPENDED SEDIMENT TRANSPORT IN CHANNEL BENDS

1. INTRODUCTION Due to the fact that three-dimensional (3D) numerical models are quite expensive to simulate flow and sediment transport processes, vertically-integrated two-dimensional (2D) models are extensively applied at present, even to the predictio…