Nitrogen removal performance and bacterial communities in zeolite trickling filter under different influent C/N ratios

Environmental Science and Pollution Research - In this study, the degradation performance of nutrients in zeolite trickling filter (ZTF) with different influent C/N ratios and aeration conditions...     

含纤维素废水生物水解的应用研究

提取植物或动物纤维所产生的高浓有机废水，含短小纤维、木质素、纤维素、半纤维素、蜡质、果胶及其分解产物(糖、脂肪酸、醇等)，较难生物处理，属含纤维素废水。试验研究和生产应用表明，生物水解对含纤维素废水中高分子有机物，可予分解并提高度水可生化性：在常温、PH约9．5时，水解池污泥浓度达6．5～16．0g/L，容积负荷达2．9kgCOD／m^3．d，COD去除率为24—36％，VFA提高3．9—5．1倍，BOD／COD提高12～16％。分析认为：中温、酸性，纤维素、木素含量低时，水解效果应更好。     

不同浸提剂对污染河道底泥中重金属的浸出影响

以某有色金属冶炼企业排放口下游河道底泥为研究对象,分别采用无机酸(盐酸、硫酸、硝酸)和有机酸(醋酸、柠檬酸、苹果酸和丁二酸)研究在不同酸性条件(pH为2~6)下Pb、Cd、Zn、Cu的浸出效果。结果表明,有机酸的浸提能力明显高于无机酸,且4种重金属的浸出浓度均随着pH的升高而迅速降低。对无机酸而言,当pH3时,重金属的浸出浓度趋于稳定;对有机酸而言,在pH为2~5的较大范围内,醋酸表现出较高的浸提能力,而柠檬酸对Pb和Cu没有明显的浸出效果。结合泥质特点,从重金属的络合、沉淀、水解、吸附等反应过程对其浸出特征进行了分析,同时提出醋酸良好的缓冲能力是其浸提效果优于其他有机酸的重要原因。     

乙草胺对土壤微生物的影响研究

研究了乙草胺在6种不同浓度下对土壤微生物种群数量及土壤中细菌、放线菌、真菌生长速率的影响.采用密闭法测定乙草胺对土壤微生物呼吸的影响.结果表明,乙草胺对土壤微生物种群数量及土壤中细菌、放线菌、真菌生长速率均有一定的抑制作用,对土壤微生物呼吸作用具有明显的抑制作用.     

Characterization of aircraft emissions and air quality impacts of an international airport

Beijing Capital International Airport(ZBAA) is the world's second busiest airport. In this study, the emissions of air pollutants from aircraft and other sources at ZBAA in 2015 were estimated using an improved method, which considered the mixing layer height calculated based on aircraft meteorological data relay(AMDAR), instead of using the height(915 m)recommended by ICAO. The yearly emissions of NO_x, CO, VOCs, SO_2, and PM_(2.5) at the airport were 8.76 × 10~3, 4.43 × 10~3, 5.43 × 10~2, 4.80 × 10~2, and 1.49 × 10~2 ton/year, respectively. The spatial–temporal distribution of aircraft emissions was systematically analyzed to understand the emission characteristics of aircraft. The results indicated that NOxwas mainly emitted during the take-off and climb phases, accounting for 20.5% and 55.5% of the total emissions. CO and HC were mainly emitted during the taxi phase, accounting for 91.6%and 92.2% of the total emissions. Because the mixing layer height was high in summer, the emissions of aircraft were at the highest level throughout the year. Based on the detailed emissions inventory, four seasons simulation using WRF-CMAQ model was performed over the domain surrounding the airport. The results indicated that the contribution to PM_(2.5) was relatively high in winter; the average impact was about 1.15 μg/m~3 within a radius of1 km around the airport. Meanwhile, the near surroundings and southwest areas of the airport are the most sensitive to PM_(2.5).     

两种河道底泥重金属污染生态危害评价方法比较研究

河道底泥作为特殊的物质形态,其评价方法与土壤和水环境评价方法均有所差异。随着河道底泥重金属污染问题越来越受到人们的关注,针对河道底泥重金属污染的评价方法也大量涌现。着重介绍了Hakanson生态风险指数法和污染负荷指数法两种操作简单、使用方便的常用方法,重点针对方法本身以及该种方法的优缺点。     

The effect of using a geotextile in a monolithic (evapotranspiration) alternative landfill cover on the resulting water balance

This paper examines the potential effects of a geotextile layer used in a lysimeter pan experiment conducted in a monolithic (evapotranspiration) soil cover trial on its resulting water balance performance. The geotextile was added to the base of the lysimeter to serve as a plant root barrier in order to delineate the root zone depth. Both laboratory data and numerical modelling results indicated that the geotextile creates a capillary barrier under certain conditions and retains more water in the soil above the soil/geotextile interface than occurs without a geotextile. The numerical modelling results also suggested that the water balance of the soil cover could be affected by an increase in plant transpiration taking up this extra water retained above the soil/geotextile interface. This finding has a practical implication on the full-scale monolithic cover design, as the absence of the geotextile in the full-scale cover may affect the associated water balance and hence cover performance. Proper consideration is therefore required to assess the final monolithic cover water balance performance if its design is based on the lysimeter results.     

Geographical distribution and risk assessment of heavy metals: a case study of mine tailings pond

ABSTRACT

In China, a large number of tailings deposited on natural surfaces, the potential risk of tailings attracts people’s attention. In this study, heavy metals distribution, geo-accumulation index, ecological risk index, microbial diversity and community were examined to evaluate the risks of a tailings pond. Results indicated the tailings pH is about 8.17, and the redox potential was lower than zero. Heavy metals could be leached and migrate from the tailings. The tailings pond had more influence on the distribution of Pb, Zn, As, Cu, and S. The influence distance of Pb, Zn, and Cu was less than 10?m, and the influence distance of As and S was less than 50?m. S and As had stronger migration capability than other elements in the soil. The biggest potential ecological risk resulted from Pb, and the distances more than 100?m had low ecological risk. The tailings decreased microbial richness and diversity of the surrounding environment. Oxidising bacteria and reducing bacteria existed in both the tailings and the surrounding soils; however, there were more oxidising and reducing microbes in the tailings than in the surrounding soils. The tailings pond currently has little impact on the environment, but the potential risk still exists.     

两相厌氧在浆粕废水处理工程中的应用

浆粕废水组分较为复杂,废水治理具有一定的技术难度,采用两相厌氧、间歇式活性污泥法和物化处理组合工艺可以取得较好的效果。生产运行表明两相厌氧工艺对CODCr、BOD5的去除效率分别达67%～78%和82%～87%,生物水解使挥发酸提高了23～34倍。根据水质和水量的变化情况,及时调整其操作参数可使水解池维持良好的运行状态。     

On-board measurements of gaseous pollutant emission characteristics under real driving conditions from light-duty diesel vehicles in Chinese cities

A total of 15 light-duty diesel vehicles(LDDVs) were tested with the goal of understanding the emission factors of real-world vehicles by conducting on-board emission measurements. The emission characteristics of hydrocarbons(HC) and nitrogen oxides(NOx) at different speeds, chemical species profiles and ozone formation potential(OFP) of volatile organic compounds(VOCs) emitted from diesel vehicles with different emission standards were analyzed. The results demonstrated that emission reductions of HC and NOxhad been achieved as the control technology became more rigorous from Stage I to Stage IV. It was also found that the HC and NOxemissions and percentage of O2 dropped with the increase of speed, while the percentage of CO2 increased. The abundance of alkanes was significantly higher in diesel vehicle emissions, approximately accounting for 41.1%–45.2%, followed by aromatics and alkenes. The most abundant species were propene,ethane, n-decane, n-undecane, and n-dodecane. The maximum incremental reactivity(MIR)method was adopted to evaluate the contributions of individual VOCs to OFP. The results indicated that the largest contributors to O3 production were alkenes and aromatics, which accounted for 87.7%–91.5%. Propene, ethene, 1,2,4-trimethylbenzene, 1-butene, and1,2,3-trimethylbenzene were the top five VOC species based on their OFP, and accounted for 54.0%-64.8% of the total OFP. The threshold dilution factor was applied to analyze the possibility of VOC stench pollution. The majority of stench components emitted from vehicle exhaust were aromatics, especially p-diethylbenzene, propylbenzene, m-ethyltoluene, and p-ethyltoluene.