垃圾填埋场渗滤液性质研究进展

从宏观、中观和微观三个尺度对目前垃圾填埋场渗滤液的性质、处理方法和研究手段进行了系列介绍与比较。比较结果表明．相对于宏观和微观尺度的渗滤液性质的研究,中观尺度的研究将更有助于指导渗滤液处理工艺的发展方向。     

老港填埋场渗滤液性质随工艺变化研究

经老港填埋场渗滤液处理系统的各处理单元处理后的流出液,用不同孔径的系列膜进行了梯度分离。分离前后的渗滤液进行了TOC、TP、TN、氨氮和可溶性P等参数的测定,并建立了各参数与不同孔径膜的关系。结果表明,此工艺对老港填埋场渗滤液的处理具有一定的功效;随着处理工艺的进行,渗滤液的组成发生了较大的改变,其中细胶体部分的百分含量增加,而可溶性部分降低;渗滤液的绝大部分污染物质集中于可溶性部分,而渗滤液中的P主要与大分子的悬浮物和粗胶体结合。     

Effective interventions on health effects of Chinese rural elderly under heat exposure

● Education and subsidy were effective interventions during short-term heat exposure. ● A new index was defined to evaluate the intervention performance. ● Blood pressure and sleep duration were more heat-sensitive for the elderly. Due to climate change, the heatwave has become a more serious public health threat with aging as an aggravating factor in recent years. There is a pressing need to detect the most effective prevention and response measures. However, the specific health effects of interventions have not been characterized on an individual scale. In this study, an intervention experiment was designed to explore the health effects of heat exposure at the individual level and assess the effects of different interventions based on a comprehensive health sensitivity index (CHSI) in Xinyi, China. Forty-one subjects were recruited randomly, and divided into one control group and three intervention groups. Interventions included education (Educate by lecturing, offering relative materials, and communication), subsidy support (offer subsidy to offset the cost of running air conditioning), and cooling-spray (install a piece of cooling-spray equipment in the yard). Results showed that systolic blood pressure (SBP) and deep sleep duration (DSD) were significantly affected by short-term heat exposure, and the effects could be alleviated by three types of interventions. The estimated CHSI indicated that the effective days of the education group were longer than other groups, while the lower CHSI of the subsidy group showed lower sensitivity than the control group. These findings provide feasible implementation strategies to optimize Heat-health action plans and evaluate the intervention performance.     

炼油厂污水处理场恶臭污染源调查及预测研究

主要对某炼油厂污水处理场恶臭污染源进行调查,确定出了重点污染源与重点污染物。以污水场曝气池为例,使用风洞采样器进行采样,三点比较式臭袋法测定恶臭浓度,确定面源源强。通过恶臭评估软件预测出一次浓度、日均浓度、夏季平均浓度和全年平均浓度,并对预测结果进行了验证。     

EDDS and EDTA-enhanced phytoextraction of metals from artificially contaminated soil and residual effects of chelant compounds

The potential of 18 different plants to be used in the chemically enhanced phytoextraction of Cu, Pb, Zn and Cd was assessed using pot experiments. Chrysanthemum coronarium L. was the species most sensitive to the application of EDTA, and had the highest enhancement of Cu and Pb concentrations in its shoots. Compared with EDTA, EDDS was more effective in enhancing the concentration of Cu in the shoots of Chrysanthemum coronarium L. and Zea mays L. grown on multi-metal contaminated soils. The EDTA-treated soil still had a significant ability to enhance the concentrations of Cu and Pb in the shoots of Zea mays L. six months after the chelant treatment. However, the EDDS-treated soil did not have any effect in enhancing the concentrations of metals in the shoots of Zea mays L. in the second crop test. The results may indicate that EDDS biodegrades more rapidly than EDTA in soil and is better in limiting potential metal leaching.     

Selection of a water-extractable phosphorus test for manures and biosolids as an indicator of runoff loss potential

The correlation of runoff phosphorus (P) with water-extractable phosphorus (WEP) in land-applied manures and biosolids has spurred wide use of WEP as a water quality indicator. Land managers, planners, and researchers need a common WEP protocol to consistently use WEP in nutrient management. Our objectives were to (i) identify a common WEP protocol with sufficient accuracy and precision to be adopted by commercial testing laboratories and (ii) confirm that the common protocol is a reliable index of runoff P. Ten laboratories across North America evaluated alternative protocols with an array of manure and biosolids samples. A single laboratory analyzed all samples and conducted a separate runoff study with the manures and biosolids. Extraction ratio (solution:solids) was the most important factor affecting WEP, with WEP increasing from 10:1 to 100:1 and increasing from 100:1 to 200:1. When WEP was measured by a single laboratory, correlations with runoff P from packed soil boxes amended with manure and biosolids ranged from 0.79 to 0.92 across all protocol combinations (extraction ratio, filtration method, and P determination method). Correlations with P in runoff were slightly lower but significant when WEP was measured by the 10 labs (r=0.56-0.86). Based on laboratory repeatability and water quality evaluation criteria, we recommend the following common protocol: 100:1 extraction ratio; 1-h shaking and centrifuge 10 min at 1500xg (filter with Whatman #1 paper if necessary); and determining P by inductively coupled plasma-atomic emission spectrometry or colorimetric methods.     

Mitigating GHG Emissions in the Humid Tropics: Case Studies from the Alternatives to Slash-and-Burn Program (ASB)

Tropical forest conversion contributes as much as 25% of the net annual CO₂ emissions and up to 10% of the N_2O emissions to the atmosphere. The net effect on global warming potential (GWP) also depends on the net fluxes of greenhouse gases from land-use systems following deforestation. Efforts to mitigate these effects must take into account not only the greenhouse gas fluxes of alternative land-use systems but also the social and economic consequences that influence their widespread adoption. The global alternatives to slash-and-burn program (ASB) investigated the net greenhouse gas emissions and profitability of a range of land-use alternatives in the humid tropics. The analysis showed that many tree-based systems reduced net GWP compared to annual cropping and pasture systems. Some of these systems are also profitable in terms of returns to land and labor. The widespread adoption of these systems, however, can be limited by start-up costs, credit limitations, and number of years to positive cash flow, in addition to the higher labor requirements. Projects that offset carbon emissions through carbon sinks in land use in the tropics might be a means of overcoming these limitations. A synthesis of the findings from this program can provide guidelines for the selection and promotion of land-use practices that minimize net global warming effects of slash-and-burn.     

Numerical simulation of flow hydrodynamics of struvite pellets in a liquid–solid fluidized bed

Phosphorus recovery in the form of struvite has been aroused in recent decades for its dual advantages in eutrophication control and resource protection.The usage of the struvite products is normally determined by the size which is largely depended on the hydrodynamics.In this study,flow behavior of struvite pellets was simulated by means of Eulerian–Eulerian two-fluid model combining with kinetic theory of granular flow in a liquid–solid fluidized bed reactor(FBR).A parametric study including the mesh size,time step,discretization strategy,turbulent model and drag model was first developed,followed by the evaluations of crucial operational conditions,particle characteristics and reactor shapes.The results showed that a cold model with the mesh resolution of 16 × 240,default time step of 0.001 sec and first order discretization scheme was accurate enough to describe the fluidization.The struvite holdup profile using Syamlal–O'Brien drag model was best fitted to the experimental data as compared with other drag models and the empirical Richardson–Zaki equation.Regarding the model evaluation,it showed that liquid velocity and particle size played important roles on both solid holdups and velocities.The reactor diameter only influenced the solid velocity while the static bed height almost took no effect.These results are direct and can be applied to guide the operation and process control of the struvite fluidization.Moreover,the model parameters can also be used as the basic settings in further crystallization simulations.     

Variation and removal efficiency of assimilable organic carbon (AOC) in an advanced water treatment system

This study investigates the microorganism growth indicator and determines the assimilable organic carbon (AOC) content at the Cheng-Ching Lake Advanced Water Treatment Plant (CCLAWTP) in Kaohsiung, Taiwan. Notably, AOC is associated with the biological stability within the water distribution network and has garnered considerable attention in the environmental engineering field in recent years. Water samples were collected from the effluent of each unit in CCLAWTP once monthly during December 2008 to November 2009. Items of water quality related to carbon concentration levels, including AOC, total organic carbon, dissolved organic carbon, UV₂₅₄, and specific ultraviolent absorbance were analyzed. Analytical results demonstrate that the average AOC concentration in raw water was 83.61 ??g/L and reduced in freshwater was controlled at an average of 50 ??g/L after an advanced treatment system of roughly 54% of AOC was removed in compliance with treatment plant standards. If AOC concentrations in freshwater can be reduced, study results can provide a direction for improving water treatment capabilities.