Municipal wastewater treatment by moving-bed-biofilm reactor with diatomaceous earth as carriers.

This study was conducted to examine the feasibility of using a moving-bed-biofilm reactor with internal circulation through aeration for the treatment of municipal wastewater. The attached film was a mixed-microorganism consortium, which used composite-refined-diatomaceous earth as novel biomass carriers to form a diatomaceous-earth-moving-bed-biofilm-reactor (DEMBBR) process. The startup of laboratory-scale, continuous-flow reactor was successfully achieved without seeding activated sludge. The DEMBBR process removed chemical oxygen demand, total phosphorus, ammonium-nitrogen, and turbidity at the highest rate of 88.5, 83, 92.3, and 96.7%, respectively, with a hydraulic retention time of only 2.5 hours. The DEMBBR was less affected by interruption and adverse operation conditions than the conventional-activated-sludge reactor. Thus, the DEMBBR could be proposed to be a cost-effective, small-wastewater-treatment-process unit.     

活性炭多维电极法去除水中腐殖酸过程与宏观动力学研究

采用活性炭多维电极法去除水中溶解态腐殖酸。实验结果表明 ,与活性炭单纯吸附法相比 ,活性炭多维电极法可显著提高对溶解态腐殖酸的去除率 ;在连续运行条件下 ,延长水力停留时间、升高槽电压、溶液偏碱性有利于腐殖酸的去除 ;高效液相色谱分析结果表明 ,电极的氧化还原作用可使有机物分子量变小或矿化 ,因而处理系统有可能延长活性炭的使用寿命     

Photocatalysis enhancement by electric field: TiO2 thin film for degradation of dye X-3B

According to the theory of photocatalysis, the efficiency of photocatalysis decreases mostly due to the recombination of photo-generated electron-hole pairs. An electric field across a photocatalyst can promote the separation of photo-generated electrons and holes and prevent them from recombination so as to enhance the efficiency of photocatalysis. And the synergetic decomposition efficiency of photocatalysis and an electric field is greater than that of the simple combine of their single efficiency. The performance of photocatalysis enhanced by electric field (PEEF) and operating conditions such as the direction of the electric field, the voltages between the two electrodes, the material of the electrodes, which may affect the efficiency of PEEF, were investigated in this paper. The results indicate that the system of PEEF abides the established theory of photocatalysis.     

水解-酸化法在味精废水处理中的应用

结合江苏南通天字味精厂的工程实例,介绍了以水解-酸化法为主体的味精废水处理工艺的原理、特点和应用中注意的问题.该工艺运行结果表明:在治理味精废水方面具有较佳的耐冲击性能;出水稳定达标;操作运行管理方便;投资成本和运行费用均较低.从其优势看有良好的应用前景.     

长江、嘉陵江(重庆段)源水有机提取物的致突变活性及其季节变化

为了确定并比较重庆主城区段长江、嘉陵江源水有机提取物的致突变性及其季节变化规律，分别于春、夏、冬季采用GDX－120大孔树脂，对位于城区上游、城区中段、城区下游以长江、嘉陵江源水的5个水厂的进厂水进行了有机物的浓缩提取。提取物的致突变活性采用经典的Ames试验平板掺入法评估，测试菌株为TA98及TA100，同时做加与不加S9的比较。结果显示，嘉陵江及长江源水的有机提取物均有不同程度的致突变活性。嘉陵江源水明显大于长江源水，城区中段源水明显大于上游段及下游段源水。多数断面显示平水期致突变活较为显著并且移码型致突变性大于碱基置换型致密变性。研究结果提示，城市污染源已导致长江、嘉陵江源水具备致突变活性，控制两江沿岸的各种水污染源已成为当务之急。     

Solubilization of substituted indole compounds by beta-cyclodextrin in water

The solubilization of four pairs of substituted indole compounds (SICs) by β-cyclodextrin (β-CD) in water was investigated. The results show that 1,2,3,4-tetrahydrocarbazole and N-methyl-1,2,3,4-tetrahydrocarbazole form 1:1 inclusion complexes with β-CD, while the other six SICs form 1:2 inclusion complexes, respectively. To each pair of SICs with similar structures, the differences between their solubilization in β-CD/water solutions has been explained by the difference of their contact area within the β-CD cavity, the difference of their molecule polarity, or the presence of hydrogen bond between SIC molecule and β-CD molecule.     

System-level responses of lake ecosystems to chemical stresses using exergy and structural exergy as ecological indicators

This paper presents the system-level responses of experimental lake ecosystems to three chemical stresses (acidification, copper and pesticide contamination) using exergy and structural exergy as ecological indicators. The results indicate that the doses or toxicity of the three chemical stressors contributed to changes in both exergy and structural exergy. Remarkable changes in exergy and structural exergy occurred under acidic conditions and in the presence of Dursban, 24D-DMA, permethrin, bifenthrin, Carbaryl, TCP, PCP, trichlorethylene, benzene, and high doses of Cu, oil, and hexazinone. This seemed to indicate that the subject ecosystems were seriously contaminated by these chemical stressors. For low doses of Cu, oil, atrazine, HCBP, and hexazinone, exergy and structural exergy were either unchanged or only slightly changed, suggesting that the lake ecosystems were not significantly impacted by these chemical stressors. Discussion of the relationships between ecosystem-level changes and structural and functional changes in stressed lake ecosystems indicates that the above-mentioned ecosystem-level changes were in accordance with the changes in structure and function. The observed changes in exergy and structural exergy were also consistent with Odum's predictions of shortened food chains, reduced resource use efficiency, poor stability, low information, and high entropy in stressed aquatic ecosystems. The findings lead the authors to conclude that it is feasible for exergy and structural exergy to serve as ecological indicators when characterizing the system-level responses of experimental lake ecosystems to chemical stress. These results for experimental lake ecosystems would be extrapolated to actual lakes.     

Titanium dioxide as photocatalyst on porous nickel: adsorption and the photocatalytic degradation of sulfosalicylic acid

The commonly used photocatalyst, TiO2 (anatase), has been immobilized on porous nickel using 3 wt.% polyvinyl alcohol (PVA) as the binder. The results show that sulfosalicylic acid (SSal) can be degraded on the developed catalytic system. The adsorption characteristics on TiO2-Ni system have been investigated. The observance of photocalytic degradation of SSal under pH values and initial concentrations can be explained by the adsorption behavior of SSal. The parameters of the Langmuir-Hinshelwood expression have been determined by different experimental ways and the results are satisfactory.     

Fractionation of heavy metals in surface sediments of Taihu Lake, East China

The BCR (European Communities Bureau of Reference) three-step sequential extraction procedure was applied to fractionate heavy metals in the sediment of Taihu Lake. For the determination of total metal concentration of the sediments, sample digestion was achieved by using HF/H2O2/HNO3 (2/1/1) acid mixture in a microwave-irradiated closed vessel system. The concentrations of Cd, Ni, Cr, Zn, Cu and Pb in various extracts solutions were analyzed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The results obtained from the BCR three-step sequential extraction indicated relatively high mobility of Zn, Cu, Pb and Ni in the sediments while Cd and Cr were poorly mobile. Enrichment of heavy metals was found in the sediments collected in the northern parts of Taihu Lake. In the sediments collected in the southern and western sides of the Lake, heavy metal concentrations were relatively low. The relationship between total organic carbon (TOC) and heavy metals concentrations in the sediments is discussed.     

Degradation of benzo[a]pyrene in soil with arbuscular mycorrhizal alfalfa

Mycorrhizal and non-mycorrhizal alfalfa (Medicago sativa) was grown in pots containing soil artificially contaminated with various levels of benzo[a]pyrene (B[a]P) (0, 1, 10 and 100 mg kg(-1)). Soil and plants were sampled after 30, 40, 50, 60 and 90 days and compared with unlanted pots. The percentage of mycorrhizal root length colonized by Glomus caledoniun was not significantly affected by the addition of B[a]P up to 10 mg kg(-1) but was significantly lower at 100 mg kg(-1)B[a]P compared with low concentrations (p < 0.05). There was no difference in soil polyphenol oxidase and dehydrogenase activity among the controls and applications of 1 and 10 mg kg(-1) of B[a]P. However, enzyme activities were significantly higher at 100 mg kg(-1) B[a]P compared with the other three treatments, and there was no mycorrhizal effect. Over a period of 90 days the concentration of B[a]P in soil in which alfalfa was grown was significantly lower than in unplanted soil (p < 0.05). Degradation rates of B[a]P added at 1, 10 and 100 mg kg(-1) without G. caledonium were 76, 78 and 53%, and with mycorrhizal inoculation were 86, 87 and 57%. The degradation rate in unplanted soil was significantly lower than in planted soil, and was significantly higher in medium- and low-B[a]P treatments than in the high B[a]P concentration tested. There is a possibility of enhancement phytoremediation of PAHs in rhizosphere soil with arbuscular mycorrhizal fungi.