悬挂链生物接触氧化工艺处理河道污水

采用悬挂链曝气式接触氧化工艺在3个时段内处理城市河道污水,通过采用磷脂法、TTC-脱氢酶活性法和MPN法研究载体表面生物膜特性,来验证装置的水质净化效果。结果表明,进水水质变化幅度较大的时段1内,水质对缺氧区和好氧区内生物膜量及活性有很大冲击,对污染物的去除效果影响不大,COD、NH+4-N、TN和TP的平均去除率分别达到75.9%、80.8%、64.6%和78.3%;进水水质稳定的时段2内,缺氧区和好氧区内生物膜量和活性要高于其他时段,COD、NH+4-N、TN和TP的平均去除率分别达到77.0%、80.6%、69.4%和55.3%;低温运行的时段3内,缺氧区和好氧区内生物膜量和活性都低于其他时段,水质净化效果明显下降,COD、NH+4-N、TN和TP的平均去除率分别为71.1%、68.5%、48.9%和46.6%。     

质子化改性交联壳聚糖的制备及其吸附硫酸根离子的性能

以壳聚糖为原料，甲醛为氨基保护剂，戊二醛为交联剂，采用反相悬浮交联法制备交联壳聚糖，再对其进行质子化改性得到质子化改性交联壳聚糖吸附剂。通过正交实验对该吸附剂的制备条件进行优化，并对其吸附水中硫酸根（SO₄^2-）的吸附等温特性和动力学进行研究，最后对制备和吸附过程进行能谱分析（EDS）并对吸附剂进行了再生实验。实验结果表明，交联反应的优化条件为：反应温度50℃、反应时间6 h、甲醛：戊二醛：壳聚糖为4.5：0.5：3（质量比）；该吸附过程符合Langmuir吸附等温模型，在25℃（298 K）下，吸附容量最大可达133.87 mg/g；吸附过程较好地符合拟二级动力学模型；EDS分析表明了交联反应、质子化改性和吸附反应均已发生；该吸附剂的再生性能良好，可以重复使用。     

Influence of filtration velocity on DON variation in BAF for micropolluted surface water treatment

Biological aerated filters (BAFs) are widely used for the treatment of micropolluted surface water. However, the biological process produces dissolved organic nitrogen (DON), which, as precursors of nitrogenous disinfection by-products, pose potential threats to drinking water safety. Therefore, to control DON in BAF effluent, it is necessary to study the influence of BAF operation parameters on DON production. In this study, the influence of filtration velocity in a BAF on DON production was investigated. Under different filtration velocity (0.5, 2, and 4 m/h) conditions, profiles of DON concentrations along the media layer were measured. The profile at a filtration velocity of 0.5 m/h showed a decreasing trend, and the ones under filtration velocities of 2 and 4 m/h fluctuated in a small range (from 0.1 to 0.4 mg/L). Moreover, the relatively high filtration velocities of 2 and 4 m/h resulted in a lower level of DON concentration. Additionally, 3D excitation-emission matrix fluorescence spectroscopy was used to characterize DON. It is found that the patterns of DON at a relatively high filtration velocity condition (4 m/h) were obviously different from the ones under low filtration velocity conditions (0.5 and 2 m/h).     

Study on NOx removal from simulated flue gas by an electrobiofilm reactor: EDTA-ferrous regeneration and biological kinetics mechanism

Environmental Science and Pollution Research - The regeneration of EDTA-FeII is a key step in electrobiofilm reduction-integrated systems for NOx removal from industrial boiler flue gas. The...     

基于EEMD和EOF的鄱阳湖流域近550 a来旱涝时空变化

利用鄱阳湖流域及周边地区5个站点1467~2016年旱涝灾害史料，结合《中国近五百年旱涝分布图集》数据和现代器测降水资料，基于相关系数权重法集成重建了鄱阳湖流域近550 a旱涝序列。采用集合经验模态分解和经验正交函数等手段分析了鄱阳湖流域近550 a来的旱涝时空变化特征。结果表明：（1）鄱阳湖流域旱涝序列的各IMF分量变化规律符合自然信号的非线性变化的特征，主要的高频变化周期有2~3 a、7~8 a；中低频变化周期有22 a、36 a；低频变化周期有110 a、220 a等。（2）旱涝序列空间场的EOF分解表明，前4个模态的累积方差贡献率为93.68%，收敛效果明显。第一模态为区域整体变化一致；第二、三模态分别代表南北方向和东西方向上旱涝变化不一致；第四模态代表赣南地区的极端降水类型。（3）主要空间模态的时间系数功率谱分析结果表明，旱涝空间场模态的变化周期与旱涝序列EEMD分解的结果基本一致。 关键词： EEMD；EOF；旱涝变化；时空特征；鄱阳湖流域     

Using ecological memory as an indicator to monitor the ecological restoration of four forest plantations in subtropical China

A large area of plantations has been established worldwide and especially in China. Evaluating the restoration status of these plantations is essential for their long-term management. Based on our previous work, we used an ecological memory (EM) approach to evaluate four 26-year-old plantations that represent four common kinds of plantations in subtropical China, i.e., mixed broad-leaved plantation (MBP), mixed coniferous plantation (MCP), eucalyptus plantation (EP), and mixed legume plantation (MLP). Comparing them with the regional climax community, i.e., monsoon evergreen broad-leaved forest (BF), all four plantations accumulated nearly the same pattern of EM during succession. EM was >50 % for soil minerals, light conditions, soil age, soil animals, and soil microbes. EM was about 25 % for soil pollen and 10 % for birds, soil seed bank, and plant species. The total EM value of the four plantations ranged from 50.96 to 52.54, which indicated that all four plantations were in the regional, natural trajectory of succession and between the early and medium successional stages. The results indicated that natural succession processes are unlikely to be accelerated by planting late-stage tree species without sufficient EM. The results also demonstrated that all four plantations were in positive successional trajectories, and the positive succession dynamics were greater in the MLP and MCP. We suggest that the entire natural succession trajectory be used to evaluate the restoration of a site and that the ultimate restoration target be divided into several milestones along the reference trajectory to monitor progress. Forest restoration may be accelerated by starting with a minimum dynamic unit supporting sufficient EM.     

Behavior and mechanism of arsenate adsorption on activated natural siderite: evidences from FTIR and XANES analysis

Activated natural siderite (ANS) was used to investigate its characteristics and mechanisms of As(V) adsorption from aqueous solution. Batch tests were carried out to determine effects of contact time, initial As(V) concentration, temperature, pH, background electrolyte, and coexisting anions on As(V) adsorption. Arsenic(V) adsorption on ANS well-fitted pseudo-second-order kinetics. ANS showed a high-adsorption capacity of 2.19 mg/g estimated from Langmuir isotherm at 25 °C. Thermodynamic studies indicated that As(V) adsorption on ANS was spontaneous, favorable, and endothermic. ANS adsorbed As(V) efficiently in a relatively wide pH range between 2.0 and 10.0, although the removal efficiency was slightly higher in acidic conditions than that in basic conditions. Effects of background electrolyte and coexisting anions were not significant within the concentration ranges observed in high As groundwater. Results of XRD and Fe K-edge XANES analysis suggested ANS acted as an Fe(II)/(III) hybrid system, which was quite effective in adsorbing As from aqueous solution. There was no As redox transformation during adsorption, although Fe(II) oxidation occurred in the system. Two infrared bands at 787 and 872 cm^?1 after As(V) adsorption suggested that As(V) should be predominantly adsorbed on ANS via inner-sphere bidendate binuclear surface complexes.     

Co-composting of livestock manure with rice straw: Characterization and establishment of maturity evaluation system

Composting is considered to be a primary treatment method for livestock manure and rice straw, and high degree of maturity is a prerequisite for safe land application of the composting products. In this study pilot-scale experiments were carried out to characterize the co-composting process of livestock manure with rice straw, as well as to establish a maturity evaluation index system for the composts obtained. Two pilot composting piles with different feedstocks were conducted for 3 months: (1) swine manure and rice straw (SM–RS); and (2) dairy manure and rice straw (DM–RS). During the composting process, parameters including temperature, moisture, pH, total organic carbon (TOC), organic matter (OM), different forms of nitrogen (total, ammonia and nitrate), and humification index (humic acid and fulvic acid) were monitored in addition to germination index (GI), plant growth index (PGI) and Solvita maturity index. OM loss followed the first-order kinetic model in both piles, and a slightly faster OM mineralization was achieved in the SM–RS pile. Also, the SM–RS pile exhibited slightly better performance than the DM–RS according to the evolutions of temperature, OM degradation, GI and PGI. The C/N ratio, GI and PGI could be included in the maturity evaluation index system in which GI > 120% and PGI > 1.00 signal mature co-composts.     

Characteristics of PM<Subscript>2.5</Subscript>, CO<Subscript>2</Subscript> and particle-number concentration in mass transit railway carriages in Hong Kong

Fine particulate matter (PM_2.5) levels, carbon dioxide (CO₂) levels and particle-number concentrations (PNC) were monitored in train carriages on seven routes of the mass transit railway in Hong Kong between March and May 2014, using real-time monitoring instruments. The 8-h average PM_2.5 levels in carriages on the seven routes ranged from 24.1 to 49.8 µg/m³, higher than levels in Finland and similar to those in New York, and in most cases exceeding the standard set by the World Health Organisation (25 µg/m³). The CO₂ concentration ranged from 714 to 1801 ppm on four of the routes, generally exceeding indoor air quality guidelines (1000 ppm over 8 h) and reaching levels as high as those in Beijing. PNC ranged from 1506 to 11,570 particles/cm³, lower than readings in Sydney and higher than readings in Taipei. Correlation analysis indicated that the number of passengers in a given carriage did not affect the PM_2.5 concentration or PNC in the carriage. However, a significant positive correlation (p < 0.001, R ² = 0.834) was observed between passenger numbers and CO₂ levels, with each passenger contributing approximately 7.7–9.8 ppm of CO₂. The real-time measurements of PM_2.5 and PNC varied considerably, rising when carriage doors opened on arrival at a station and when passengers inside the carriage were more active. This suggests that air pollutants outside the train and passenger movements may contribute to PM_2.5 levels and PNC. Assessment of the risk associated with PM_2.5 exposure revealed that children are most severely affected by PM_2.5 pollution, followed in order by juveniles, adults and the elderly. In addition, females were found to be more vulnerable to PM_2.5 pollution than males (p < 0.001), and different subway lines were associated with different levels of risk.     

Research status,challenges and future prospects of renewable synthetic fuel catalysts for CO2 photocatalytic reduction conversion

Environmental Science and Pollution Research - In recent years, with global climate change, the utilization of carbon dioxide as a resource has become an important goal of human society to achieve...