三维电解法深度处理电解锰废水技术研究

实验研究了模拟含锰废水在三维电解槽中的电化学氧化过程.考察了电解时间、电解电压及锰废水初始浓度对锰去除效果的影响,并确定适宜的反应条件.实验表明,在填充活性炭与树脂的条件下,在低电压短时间内,充分提高填充粒子的利用率,达到较好的锰离子去除效果.     

Experience,but not distance,influences the recruitment precision in the stingless bee <Emphasis Type="Italic">Scaptotrigona mexicana</Emphasis>

Recruitment precision, i.e. the proportion of recruits that reach an advertised food source, is a crucial adaptation of social bees to their environment. Studies with honeybees showed that recruitment precision is not a fixed feature, but it may be enhanced by factors like experience and distance. However, little is known regarding the recruitment precision of stingless bees. Hence, in this study, we examined the effects of experience and spatial distance on the precision of the food communication system of the stingless bee Scaptotrigona mexicana. We conducted the experiments by training bees to a three-dimensional artificial patch at several distances from the colony. We recorded the choices of individual recruited foragers, either being newcomers (foragers without experience with the advertised food source) or experienced (foragers that had previously visited the feeder). We found that the average precision of newcomers (95.6 ± 2.61%) was significantly higher than that of experienced bees (80.2 ± 1.12%). While this might seem counter-intuitive on first sight, this “loss” of precision can be explained by the tendency of experienced recruits to explore nearby areas to find new rewarding food sources after they had initially learned the exact location of the food source. Increasing the distance from the colony had no significant effect on the precision of the foraging bees. Thus, our data show that experience, but not the distance of the food source, affected the patch precision of S. mexicana foragers.     

电子受体类型对聚磷污泥胞外聚合物的影响研究

采用3种电子受体(硝氮、亚硝氮、氧),在SBR反应器中分别驯化了具有稳定除磷能力的聚磷污泥。对比研究了不同聚磷污泥胞外聚合物(EPS)的组分与含量,结合三维荧光光谱对EPS中有机物质进行分析。研究表明,以硝氮、亚硝氮为电子受体的聚磷污泥EPS平均浓度较为接近,分别为115.6mg/gVSS、133.5 mg/gVSS,由厌氧段至缺氧段,EPS总浓度有所下降。以氧为电子受体聚磷污泥的EPS平均浓度相对较高,为194.5 mg/gVSS,由厌氧段至好氧段,EPS总浓度略有升高。不同聚磷污泥的EPS组分均以胞外蛋白为主,占EPS总量的53%~65%,多糖与核酸占EPS总量28%~34%、5%~7%。三维荧光光谱显示3种聚磷污泥EPS均具有芳香结构蛋白质、可溶性代谢物的荧光峰,另外,以硝氮为电子受体的聚磷污泥还具有明显的腐殖酸类物质的荧光峰。研究结果表明电子受体对聚磷污泥EPS的组分、浓度、有机质类别有一定的影响。     

Electrochemical remediation of copper (II) from an industrial effluent Part II: three-dimensional foam electrodes

A batch recycle removal of copper ions from an industrial effluent by means of copper foam cathodes was tested. A constant current of 750 A was applied to the cell in order to perform the reduction. Copper depletion was investigated at different solution flow rates and a removal greater than 98% was obtained with a flow rate of 1000 l/h. The influence of initial metal concentration on copper deposition and current efficiency is also discussed.     

Evidence on the causes of the rising levels of CODMn along the middle route of the South-to-North Diversion Project in China: The role of algal dissolved organic matter

As the biggest inter-basin water transfer scheme in the world,the South-to-North Water Diversion Project（SNWD） was designed to alleviate the water crisis in North China.The main channel of the middle route of the SNWD is of great concern in terms of the drinking water quality.In this study,we tested the hypothesis that the dissolved organic matter（DOM） derived from the planktonic algae causes the rising levels of COD_Mn along the middle route by monitoring data on water quality（2015-20...     

Advanced treatment of wet-spun acrylic fiber manufacturing wastewater using three-dimensional electrochemical oxidation

A three-dimensional electrochemical oxidation(3D-EC) reactor with introduction of activated carbon(AC) as particle micro-electrodes was applied for the advanced treatment of secondary wastewater effluent of a wet-spun acrylic fiber manufacturing plant. Under the optimized conditions(current density of 500 A/m~2, circulation rate of 5 mL/min, AC dosage of 50 g, and chloride concentration of 1.0 g/L), the average removal efficiencies of chemical oxygen demand(COD_(cr)), NH3–N, total organic carbon(TOC), and ultraviolet absorption at 254 nm(UV_(254)) of the 3D-EC reactor were 64.5%, 60.8%, 46.4%, and 64.8%, respectively; while the corresponding effluent concentrations of COD_(cr), NH_3–N, TOC, and UV_(254) were 76.6, 20.1, and42.5 mg/L, and 0.08 Abs/cm, respectively. The effluent concentration of COD_(cr) was less than 100 mg/L, which showed that the treated wastewater satisfied the demand of the integrated wastewater discharge standard(GB 8978-1996). The 3D-EC process remarkably improved the treatment efficiencies with synergistic effects for COD_(cr), NH_3–N, TOC, and UV_(254) during the stable stage of 44.5%, 38.8%, 27.2%, and 10.9%, respectively, as compared with the sum of the efficiencies of a two-dimensional electrochemical oxidation(2D-EC) reactor and an AC adsorption process, which was ascribed to the numerous micro-electrodes of AC in the 3D-EC reactor. Gas chromatography mass spectrometry(GC–MS) analysis revealed that electrochemical treatment did not generate more toxic organics, and it was proved that the increase in acute biotoxicity was caused primarily by the production of free chlorine.     

Rookery Bay and Naples Bay circulation simulations: Applications to tides and fresh water inflow regulation

A three-dimensional, baroclinic numerical circulation model is applied to the combined Rookery Bay and Naples Bay estuary complex. We focus on two aspects of the model simulations: the tidal circulation, for which we have observations of sea level and currents at several stations spanning Rookery Bay, and the salinity variations, for which we have observations at one station. After establishing model veracity through quantitative comparisons with observations, we use the model to address salinity changes that could arise due to regulatory fresh water flow rate modifications. Two different sets of experiments are performed. The first considers the salinity changes in Rookery Bay by increasing the fresh water flow rates into Henderson Creek through the addition of either 1.4 m³/s or 2.8 m³/s to the ambient flow rates. The second considers the salinity changes in Naples Bay by decreasing the fresh water flow rates through the subtraction of 9.9 m³/s from the Golden Gate Canals’ ambient flow rates. All of these scenarios result in significant, quantifiable salinity changes within the Rookery Bay and Naples Bay estuary complexes, demonstrating the environmental management utility of using high resolution, three-dimensional, numerical circulation models, as applied herein, for assessing the water properties of complex, multi-connected estuarine systems.     

Trans-boundary air pollution over remote islands in Japan: observed data and estimates from a numerical model

Observations of air pollutants were conducted in remote Japanese islands (Oki Island and Okinawa Island) in early spring to clarify the extent of trans-boundary air pollution from the Asian continent. A three-dimensional Eulerian model calculation, which included parameters on emission, transport and transformation of sulfur oxides, nitrogen oxides and ammonia, was performed to compile sulfate isosurface concentrations over the observational sites. Concentrations of non-sea-salt sulfate (nss-SO₄²⁻) of greater than 10 μg m⁻³ were observed at Oki after the northeastward passage of low-pressure systems in the Sea of Japan. At these times, the weather showed a typical winter pattern and air pollutants over China were transported southeastward to Japan with the northwesterly wind. The model calculation reproduced the observed variations of nss-SO₄²⁻ concentration well, except for one case in which the model calculation could not reproduce the extremely low nss-SO₄²⁻ concentration observed on 8 March. In Hedo (Okinawa Island), we observed long-lasting (3 days) medium concentrations of nss-SO₄²⁻ (approximately 5 μg m⁻³). Although the model reproduced these observed medium concentrations well, in general the observed results were reproduced better for Oki than for Hedo. Under the synoptic weather conditions of early spring, high concentrations of nss-sulfate were sometimes transported to these remote Japanese islands from areas of continental Asia with a strong outflow of air pollutants.     

The impact of natural and anthropogenic hydrocarbons on the tropospheric budget of carbon monoxide

A method to quantify the relative contributions of surface sources and photochemical production of atmospheric carbon monoxide has been implemented in a three-dimensional chemical-transport model. The impact of biogenic and anthropogenic hydrocarbons has been calculated. The oxidation of isoprene contributes to about 10% of the global tropospheric burden of carbon monoxide, with a maximum contribution over southern America and Africa. Oxidation of methane and terpenes contribute to 28 and 2%, respectively, of the tropospheric burden of CO. The oxidation of the other hydrocarbons, which include ethane, propane, ethylene, propylene and the surrogate hydrocarbon representing other hydrocarbons results in 12% of the CO tropospheric burden, among which 69% results from the oxidation of hydrocarbons of biologic origin. The overall global CO yield from the oxidation of isoprene is estimated to be 23% on a carbon basis. Comparisons between model results and the few available observations of isoprene, terpenes and their oxidation products show that there is no evidence that the current global isoprene emissions proposed in the IGAC/GEIA emissions data base are substantially overestimated, as suggested by previous studies.     

活性炭颗粒填充三维电极电化学烟气脱硫的研究

基于三维电极电化学技术较高的反应效率和不产生废弃物等优点,将这一先进的反应器运用到烟气脱硫领域.用活性炭作为工作电极,在通电状况下,将模拟烟气通入反应器发生反应.通过一系列试验,分析了填充床厚度、槽电压、进气流量、通电时间对脱硫率的影响,并且探讨了该反应的反应原理.