Improved dark ambient degradation of organic pollutants by cerium strontium cobalt perovskite

This work investigates the effect of cerium substation into strontium cobalt perovskites(CeSrCoO) for the oxidative degradation of Orange Ⅱ(OII) in dark ambient conditions without the aid of any external stimulants such as light,heating or chemical additives.The OII degradation rate by CeSrCoO reached 65% in the first hour,whilst for the blank sample without cerium(SrCoO) took over 2 hr to reach the same level of OII degradation.Hence,the cerium substitution improved the catalytic activity of the perovskite material,mainly associated with the Ce_(0.1)Sr_(0.9)CoO_3 perovskite phase.Upon contacting CeSrCoO,the-N=Nazo bonds of the OII molecules broke down resulting in electron donation and the formation of by-products.The electrons are injected into the CeSrCoO and resulted in a redox pair of Co~(3+)/Co~(2+),establishing a bridge for the electron transfer between OII and the catalysts.Concomitantly,the electrons also formed reactive species(·OH) responsible for OII degradation as evidenced by radical trapping experiment.Reactive species were formed via the reaction between 02 and donated electrons from OII with the aid of cobalt redox pair.As the prepared materials dispensed with the need for light irradiation and additional oxidants,it opens a window of environmental applications for treating contaminated wastewaters.     

环境温度下SBR实现稳定部分亚硝化研究

采用SBR反应器建立了一套通过特定pH终值调控曝气停止点,以实现稳定部分亚硝化的策略,整个运行过程分为3个阶段,阶段Ⅰ启动亚硝化,阶段Ⅱ在稳定亚硝化的同时探索pH终值的设定规律,阶段Ⅲ采用pH终值设定规律实现稳定部分亚硝化,通过跨越夏、冬季（7~35℃）共148d的运行,考察SBR系统内有机物、氮素的转化规律,并分析不同温度（23、18、13℃）对部分亚硝化反应过程的影响.结果表明,在低DO（0.2~0.4mg/L）和MLSS为4000mg/L的条件下,控制pH终值为（7.73±0.02）,使出水FA在0.5~1.2mg/L,可稳定部分亚硝化期间的出水NO₂^--N/NH₄⁺-N值在1~1.4之间,出水亚硝积累率（NAR）维持在85%以上,有机物去除率在60%以上.比氨氧化速率、比亚硝态氮氧化速率、比COD去除速率均随温度下降而降低,但降低趋势较缓,且反应均能稳定完成.     

Degradation of phenol in an upflow anaerobic sludge blanket(UASB) reactor at ambient temperatureKE

A synthetic wastewater containing phenol as sole substrate was treated in a 2.8 L upflow anaerobic sludge blanket(UASB) reactor at ambient temperature. The operation conditions and phenol removal efficiency were discussed, microbial population in the UASB sludge was identified based on DNA cloning, and pathway of anaerobic phenol degradation was proposed. Phenol in wastewater was degraded in an UASB reactor at loading rate up to 18 gCOD/(L·d), With a 1:1 recycle ratio, at 26(1℃, pH 7.0-7.5. An UASB reactor was able to remove 99% of phenol up to 1226 mg/L in wastewater with 24 h of hydraulic retention time(HRT). For HRT below 24 h, phenol degradation efficiency decreased with HRT, from 95.4% at 16 h to 93.8% at 12 h. It further deteriorated to 88.5% when HRT reached 8 h. When the concentration of influent phenol of the reactor was 1260 mg/L(corresponding COD 3000 mg/L), with the HRT decreasing(from 40 h to 4 h, corresponding COD loading increasing), the biomass yields tended to increase from 0.265 to 3.08 g/(L·d). While at 12 h of HRT, the biomass yield was lower. When HRT was 12 h, the methane yield was 0.308 L/(gCOD removed), which was the highest. Throughout the study, phenol was the sole organic substrate. The effluent contained only residual phenol without any detectable intermediates, such as benzoate, 4-hydrobenzoate or volatile fatty acids(VFAs). Based on DNA cloning analysis, the sludge was composed of five groups of microorganisms. Desulfotomaculum and Clostridium were likely responsible for the conversion of phenol to benzoate, which was further degraded by Syntrophus to acetate and H2/CO2. Methanogens lastly converted acetate and H2/CO2 to methane. The role of epsilon-Proteobacteria was, however, unsure.     

Degradation of phenol in an upflow anaerobic sludge blanket (UASB) reactor at ambient temperature

IntroductionPhenolistherawmaterialforthecommercialproductionofawidevarietyofresins ,includingphenolicresinsasconstructionmaterialsforautomobilesandappliances,expoxyresinsasadhesives ,andpolyamideforvariousapplications.Inaddition ,phenolsareoftenfoundinwas…     

常温处理生活污水微氧高效颗粒污泥反应器内颗粒污泥性能研究

为了分析微氧高效颗粒污泥反应器(EGSB反应器)在环境温度下处理实际生活污水时高效稳定运行的可行性,对15~26℃常温处理实际生活污水微氧EGSB反应器内颗粒污泥活性、沉淀性能、粒径分配、形态等进行研究.结果表明,15~26℃常温处理实际生活污水微氧EGSB反应器稳定运行时颗粒污泥沉速在11~79m·h-1之间,低沉速污泥有少量上浮至三相分离器底部甚至三相分离器上部,但没有出现污泥的流失,污泥浓度达到28g·L-1（以MLSS计）,可获得93.4%、83.8%、74.7%和44.0%的高COD、NH+4-N、TN和TP去除率;污泥产甲烷活性并没有降低,甚至比单纯厌氧时还有所偏高;颗粒污泥的平均粒径增大,主要集中0.63~2.00mm之间,质量分数达到了89%,既能保证反应器内的高污泥浓度,又能保证污染物质向颗粒表面和颗粒内部的高效传质,提高污染物质的转化率.颗粒污泥不同层面上微生物菌群发生了很大变化,外层丝状菌占优势,内层杆菌、丝状菌、球菌混生.微生物菌群排列紧密,细胞间紧密结合,集群协同作用使代谢物质能够以最短距离高效传递,保证了微氧EGSB反应器在常温、低浓度下的高效稳定运行.     

基于周围环境目标值估算的企业边界大气污染物限值分析

从40余项国家大气固定污染源污染物排放标准以及地方恶臭污染物排放标准中筛选出已制定企业边界限值的36种大气污染物,提出适用于限值分析的方法,基于周围环境目标值（AMEG）设置了参考区间,对比分析了我国与美国化学有害因素职业接触限值时间加权平均容许浓度（TWA）的差异。结果表明,36种大气污染物可分为3类：1）出现在国家大气污染物综合排放标准等制定和发布年限较长标准中且限值较为宽松的8种污染物;2）限值未受嗅阈值影响的13种污染物,其中12种污染物的限值与AMEG估算结果的8.4倍较为接近;3）限值受嗅阈值影响的15种污染物,其中部分污染物的限值接近AMEG估算结果,部分限值接近嗅阈值。参与对比分析的255种化学有害因素中,我国和美国的TWA相等的有44种,占比不超过20%,差异在±1倍之内的约占85%,在±5倍以上的约占7%。研究显示,现行大气污染物排放标准中的企业边界限值有效保护了人体健康和生态环境,应对制定和发布年限较长且限值较为宽松的标准,以及限值高于嗅阈值的标准开展研究,分析限值的合理性。在制定企业边界大气污染物限值时,应广泛收集更多来源的职业接触限值数据并分析其适用性。

     

Performance of a completely autotrophic nitrogen removal over nitrite process for treating wastewater with different substrates at ambient temperature

The stability and parameters of a bio-ceramic filter for completely autotrophic nitrogen removal were investigated.The completely autotrophic nitrogen removal over nitrite(CANON) reactor was fed with different concentrations of ammonia(400,300,and 200mg N/L) but constant influent ammonia load.The results showed that the CANON system can achieve good treatment performance at ambient temperature(15-23°C).The average removal rate and removal loading of NH4+-N and TN was 83.90%,1.26kg N/(m3·day),and 70.14%,1.09kg N/(m3·day),respectively.Among the influencing factors like pH,dissolved oxygen and alkalinity,it was indicated that the pH was the key parameter of the performance of the CANON system.Observing the variation of pH would contribute to better control of the CANON system in an intuitive and fast way.Denaturing gradient gel electrophoresis analysis of microorganisms further revealed that there were some significant changes in the community structure of ammonium oxidizing bacteria,which had low diversity in different stages,while the species of anaerobic ammonium oxidizing(anammox) bacteria were fewer and the community composition was relatively stable.These observations showed that anaerobic ammonia oxidation was more stable than the aerobic ammonia oxidation,which could explain that why the CANON system maintained a good removal efficiency under the changing substrate conditions.     

Torpor at high ambient temperature in a neotropical didelphid,the grey short-tailed opossum (Monodelphis domestica)

The grey short-tailed opossum, Monodelphis domestica, has been an established research animal for more than five decades, but relatively, little is known about its thermophysiology. Here we studied core body temperature (T _b) and metabolic rate (MR) of female adult M. domestica housed in the laboratory at an ambient temperature (T _a) of 26 °C. In expanding previous reports, the average recorded core T _b of M. domestica was 34.3 °C. The T _b of an individual M. domestica can drop below 30 °C (minimal T _b: 28.6 °C) accompanied by a reduction in MR of up to 52 % even while having ad libitum access to food. These findings demonstrate for the first time the presence of spontaneous torpor in M. domestica. Metabolic suppression at relatively high T _a and T _b furthermore broadens our perspective on the use of torpor as a metabolic strategy not just restricted to cold climates.     

Co-fermentation of waste activated sludge with food waste for short-chain fatty acids production: effect of pH at ambient temperature

Effect of pH ranging from 4.0 to 11.0 on cofermentation of waste activated sludge (WAS) with food waste for short-chain fatty acids (SCFAs) production at ambient temperature was investigated in this study. Experimental results showed that the addition of food waste significantly improved the performance of WAS fermentation system, which resulted in the increases of SCFAs production and substrate reduction. The SCFAs production at pH 6.0, 7.0, 8.0, and 9.0 and fermentation time of 4 d was respectively 5022.7, 6540.5, 8236.6, and 7911.7 mg COD·L⁻¹, whereas in the blank tests (no pH adjustment, pH 8.0 (blank test 1), no food waste addition, pH 8.0 (blank test 2), and no WAS addition (blank test 3)) it was only 1006.9, 971.1, and 1468.5 mg COD·L⁻¹, respectively. The composition of SCFAs at pH from 6.0 to 9.0 was also different from other conditions and propionic acid was the most prevalent SCFA, which was followed by acetic and n-butyric acids, while acetic acid was the top product under other conditions. At pH 8.0 a higher volatile suspended solids (VSS) reduction of 16.6% for the mixture of WAS and food waste than the sole WAS indicated a synergistic effect existing in fermentation system with WAS and food waste. The influence of pH on the variations of nutrient content was also studied during anaerobic fermentation of the mixture of WAS and food waste at different pH conditions. The release of NH₄⁺-N increased with fermentation time at all pH values investigated except 4.0, 5.0 and in blank test one. The concentrations of soluble phosphorus at acidic pHs and in the blank test one were higher than those obtained at alkaline pHs. Ammonia and phosphorus need to be removed before the SCFAs-enriched fermentation liquid from WAS and food waste was used as the carbon source.     

LaBO3钙钛矿催化剂的VOCs催化燃烧特性

采用共沉淀法制备了LaBO3(B=Cr、Fe、Mn、Co、Ni)钙钛矿催化剂,并用XRD、BET、H2-TPR、O2-TPD等手段对其进行了表征,考察了催化剂对苯、甲苯、乙酸乙酯和丙酮的催化燃烧性能.结果表明,Cr、Fe钙钛矿晶相中存在少量的La2CrO6和La2O3杂晶相,破坏了其活性结构.Mn、Co、Ni则能与La形成完善的钙钛矿晶相,且表现出优良的催化性能,其中LaMnO3为阳离子缺陷结构,存在较丰富的晶格氧,更适合催化燃烧C—H键键能较高和难以活化的有机分子(如苯);LaCoO3、LaNiO3属于阴离子缺陷钙钛矿结构,存在更丰富的表面氧,更适合催化燃烧易在低温下活化的含氧类有机分子(如乙酸乙酯、丙酮).     

诱导结晶反应中介稳区的研究

CaCl₂-Na₂CO₃溶液体系中c(Ca2+)和c(CO₃2-)处于介稳区中,是该体系诱导结晶反应能够进行的前提条件.临界值点是介稳区的边界点,应用电导率法测定CaCl₂-Na₂CO₃溶液体系的临界值点,对影响临界值的温度,pH,反应时间和搅拌强度等因素进行了研究,绘制了不同条件下CaCl₂-Na₂CO₃溶液体系的介稳区.结果表明,降低温度,增加溶液的pH,搅拌强度适中能够降低出现临界值时的电导率,增加介稳区的面积.考虑到试验的可操作性和成本等因素,确定CaCl₂-Na₂CO₃溶液体系诱导结晶反应的最佳条件:温度为25 ℃,pH为9.0,反应时间为10 min,搅拌强度为200 r/min.在最佳反应条件下,c(Ca2+)和c(CO₃2-)满足3.496×10-10［Ca2+］-1.182 6<［ CO₃2-］<4.96×10-9［Ca2+］>/sup>-1时,诱导结晶反应能够在介稳区中进行.      

加压条件下石灰石的脱硫反应研究

对石灰石在加压条件下的脱硫反应进行了实验研究。实验采用加压热重分析（PTGA）法,得出了加压时石灰石脱硫反应转化率数据。当压力为1.15MPa时,转化率在30.5％～45％之间。测定了加压条件下反应温度、SO₂浓度和石灰石品种对CaCO₃转化率的影响并建立了反应数学模型并由模型计算了脱硫反应动力学参数。最后对反应机理进行了分析。     

Variation of concentration of ambient aerosols in Tokyo

The number concentration of aerosol particles dispersed in the urban atmosphere was measured at Kagurazaka in central Tokyo from January 1980 to December 1987.Aitken particle number concentrations were measured with a Pollak condensation nuclei counter and a diffusion battery. The characteristic radius was deduced, using the DeMarcus equation, from the measured concentrations. Mie particle number concentrations ranging from 0.055 to 2.5 μm in radius were measured with two optical particle counters. Slope and intercept of the Junge distribution were calculated for particles > 0.15 μm. The main results are as follows.

• 1.(1) For these 8 yr, there are no long-term trends in the particle number concentrations, characteristic radius, and slope and intercept of the Junge distribution.
• 2.(2) Aitken particle number concentrations show regular seasonal variations, with a maximum during winter and a minimum during summer. They also show regular diurnal variations, with an increase during daytime and a minimum in the early morning. Detailed discussions suggest that these variations are affected by anthropogenic sources and meteorological conditions.
• 3.(3) Mie particle number concentrations show neither a clear seasonal nor diurnal variation. The variations are strongly dependent on meteorological conditions. Our careful analysis shows that wind speed is most important of the meteorological elements. Mie particle number concentrations decrease as wind speed increases, often by as much as two-thirds. This effect was observed for all wind directions.

     

The soiling of materials in the ambient atmosphere

Models describing the rate of soiling of exposed surfaces due to the deposition and accumulation of particulate matter from the atmosphere are reviewed. Samples of white painted wood were exposed for 110 days in the ambient atmosphere. Separate samples were sheltered and unsheltered from rainfall. Reflectance was measured daily. Results are compared with recently published studies in the U.S.A. (samples in the ambient atmosphere) and the U.K. (samples in a road tunnel). Experimental soiling rates were compared with predicted values. Existing models were satisfactory for predicting soiling in a tunnel but underestimated soiling in an ambient situation; a revised formulation is proposed for this situation. Rainfall generally produced a cleaning effect but redistribution of washed-off material could produce enhanced soiling.     

The soiling of materials in the ambient atmosphere

Models describing the rate of soiling of exposed surfaces due to the deposition and accumulation of particulate matter from the atmosphere are reviewed. Samples of white painted wood were exposed for 110 days in the ambient atmosphere. Separate samples were sheltered and unsheltered from rainfall. Reflectance was measured daily. Results are compared with recently published studies in the U.S.A. (samples in the ambient atmosphere) and the U.K. (samples in a road tunnel). Experimental soiling rates were compared with predicted values. Existing models were satisfactory for predicting soiling in a tunnel but underestimated soiling in an ambient situation; a revised formulation is proposed for this situation. Rainfall generally produced a cleaning effect but redistribution of washed-off material could produce enhanced soiling.     

环境空气中异丙醇的测定

建立了顶空气相色谱法测定环境空气中异丙醇的方法。空气中异丙醇经蒸馏水吸附,顶空进样氢火焰离子化检测器检测,时间定性,峰面积定量。本方法前处理简便,分析灵敏度高,不使用有机试剂,满足环境分析要求。     

典型重化工园区产能增加对城市O3浓度影响

重化工园区产能增加将加大园区挥发性有机物(VOCs)排放总量,进而影响本地及周边城市O₃浓度.珠三角实施的“VOCs倍量替代”政策可在城市层面有效抵消重化工园区VOCs排放量上升的不利影响,还可进一步降低城市VOCs排放总量,实现区域O₃浓度下降.以惠州市某大型重化工园区为例,编制2018—2020年重化工园区产能增加以及实施“VOCs倍量替代”政策的污染物排放清单,基于WRF-CMAQ模拟体系,定量分析多种情景下园区在基准年(2017年)7—10月气象条件下对惠州市及周边城市O₃影响程度.研究表明,重化工园区增产而增加VOCs排放4101.96 t,“VOCs倍量替代”综合减排余量7298.97 t;“VOCs倍量替代”政策可有效解决重化工园区增产对O₃浓度的不利影响,其中7月最为显著,主导东南风下风向的深圳市及惠州市大亚湾管委会站点O₃浓度降幅最大,分别为3.9μg·m^-3(下降率2.97%)和7μg·m^-3(下降率4.95%);...     

Measurement of the crystallization humidities of ambient aerosol particles

Atmospheric aerosols were sampled in Riverside, California, Grand Canyon, Arizona, and Mojave Desert, California, with controlled temperature-r.h. nephelometry. Ninety-one per cent of the detectable crystallization humidities for atmospheric aerosols were between 10 and 45% for all three sites. Minimum and maximum crystallization humidity data could be explained by the potential existence of external aerosol particle mixtures. These results were consistent at all three sampling sites despite the differences in aerosol particle population density and dominant air masses.     

Evaluation of ambient air quality in Guangzhou, China

On the basis of the reported air quality index （API） and air pollutant monitoring data provided by the Guangzhou Environment Monitoring Stations over the last twenty-five years, the characteristics of air quality, prominent pollutants, and variation of the average annual concentrations of SOE, NOE, total suspended particulate （TSP）, fine particulates （PM10）, CO and dustfall in Guangzhou City were analyzed. Results showed that TSP was the prominent pollutant in the ambient air environment of Guangzhou City. Of the prominent pollutants, TSP accounted for nearly 62%, SOE 12.3%, and NOx 6.4%, respectively. The average API of Guangzhou over 6 years was higher than that of Beijing, Tianjin, Nanjing, Hangzhou, Suzhou and Shanghai, and lower than that of Shenzhen, Zhuhai and Shantou. Concentrations of air pollutants have shown a downward trend in recent years, but they are generally worse than ambient air quality standards for USA, Hong Kong and EU. SOE and NOx pollution were still serious, impling that waste gas pollution from all kinds of vehicles had become a significant problem for environmental protection in Guangzhou. The possible causes of worsening air quality were also discussed in this paper.