混凝法深度处理印染废水中试研究

采用"高效混凝沉淀-过滤"深度处理工艺处理印染废水二级生化出水,并将混凝沉淀污泥回流.实验结果表明,混凝剂聚合氯化铝加入量为160 mg/L时,COD去除率平均可达34.6%,TP去除率平均达到87.9%,平均出水TP为0.3 mg/L.气相色谱-质谱分析和元素分析结果表明混凝沉淀工艺对有机物和TP的去除效果良好.     

Removal of Cr(VI) from simulative contaminated groundwater by iron metal

The Cr(VI) removal from simulative contaminated groundwater using zero-valent iron (Fe⁰) filings, Fe⁰ powder and nanoscale Fe⁰ in batch experimental mode was studied. Cr(VI) is a primary pollutant of some soils and groundwater. Zero-valent iron, an important natural reductant, could transform Cr(VI) to Cr(III) which is much less toxic and immobile. The Cr(VI) removal percentage was 87% at a metal to solution ratio of 6 g l⁻¹ for commercial iron powder (200 mesh) in 120 min, and 100% Cr(VI) was removed when the metal to solution ratio was 10 g l⁻¹. The results demonstrates that the Cr(VI) removal percentage was affected apparently by pH, the amount of Fe powder and the reaction temperature. The Cr(VI) removal percentage with nanoscale Fe⁰ was much higher than those with Fe⁰ filings or Fe⁰ powder at the same reaction time. Electrochemical analysis of the reaction process led to the conclusion that the Cr(VI) trended to form Cr(III) hydroxide under the reaction conditions. The kinetics analysis showed that Cr(VI) reduction by Fe⁰ could be described as a pseudo-first-order kinetics model.     

A case study predicting environmental impacts of urban transport planning in China

Predicting environmental impacts is essential when performing an environmental assessment on urban transport planning. System dynamics (SD) is usually used to solve complex nonlinear problems. In this study, we utilized system dynamics (SD) to evaluate the environmental impacts associated with urban transport planning in Jilin City, China with respect to the local economy, society, transport, the environment and resources. To accomplish this, we generated simulation models comprising interrelated subsystems designed to utilize changes in the economy, society, road construction, changes in the number of vehicles, the capacity of the road network capacity, nitrogen oxides emission, traffic noise, land used for road construction and fuel consumption associated with traffic to estimate dynamic trends in the environmental impacts associated with Jilin's transport planning. Two simulation scenarios were then analyzed comparatively. The results of this study indicated that implementation of Jilin transport planning would improve the current urban traffic conditions and boost the local economy and development while benefiting the environment in Jilin City. In addition, comparative analysis of the two scenarios provided additional information that can be used to aid in scientific decision-making regarding which aspects of the transport planning to implement in Jilin City. This study demonstrates that our application of the SD method, which is referred to as the Strategic Environmental Assessment (SEA), is feasible for use in urban transport planning.     

Generalized models for prediction of pentachlorophenol dissipation dynamics in soils

Dissipation of pentachlorophenol (PCP) in soil was investigated and the chemical relationships with soil properties were addressed. The results indicate that the dissipation of extractable PCP residues can be described using first-order kinetics equations, with a half-dissipation time (T(1/2)) ranging from 6.5 to 173.3d. The sharply different patterns of PCP dissipation in different soils were closely related to soil properties. Correlations of stepwise regression equations obtained were significant at 0.01 probability level between soil parameters and extractable PCP residues (R(2)=0.974**) as well as T(1/2) values (R(2)=0.882**). Using pH together with organic carbon content (OC) and soil particle size distribution, the dissipation dynamics of PCP in soil could be accurately predicted.     

有毒气体危害区域划分之临界浓度标准研究

通过研究毒物伤害准则进而界定有毒气体危害浓度,对有毒气体泄漏扩散后的危害区域进行分级划分,以采取相应的防护措施,最大限度的即时有效的减轻有毒气体对人员的伤害.最后,以氯为例,对比其在不同伤害准则下危害区域划分临界浓度标准值,数值差别较大,因此在使用时应根据实际情况加以判断,选择最适当的标准来划分危害区域.     

Effect of heavy metals (Cu, Pb, and As) on the ultrastructure of Sargassum pallidum in Daya Bay, China

Concentrations of Cu, Pb, and As were determined in seawater, surface sediment, Sargassum pallidum collected from the Daya Bay, China. The influence of metal contamination on the marine alga was investigated at chemical and ultrastructural level. Mean concentrations of Cu (19.44 mg kg^?1) and Pb (33.99 mg kg^?1) were found to be high in sediment, whereas concentration of As (122.29 mg kg^?1) in S. pallidum was higher than that in water and sediment. The ultrastructure of S. pallidum cells was anomalous and aberrant. Energy-dispersive x-ray spectroscopic analysis revealed that the nanometal particles in the form of comparatively high-electron density substance diffused in the cell structures constituted by Cu, Pb, As, etc. There is a remarkable similarity or correspondence in the anomalous elements between the geochemistry and the botanic cell, and the heavy metals have potential hazardous effect on the ocean ecology system in Daya Bay.     

Robust Regression with Data-Dependent Regularization Parameters and Autoregressive Temporal Correlations

We introduce robust procedures for analyzing water quality data collected over time. One challenging task in analyzing such data is how to achieve robustness in presence of outliers while maintaining high estimation efficiency so that we can draw valid conclusions and provide useful advices in water management. The robust approach requires specification of a loss function such as the Huber, Tukey’s bisquare and the exponential loss function, and an associated tuning parameter determining the extent of robustness needed. High robustness is at the cost of efficiency loss in parameter loss. To this end, we propose a data-driven method which leads to more efficient parameter estimation. This data-dependent approach allows us to choose a regularization (tuning) parameter that depends on the proportion of “outliers” in the data so that estimation efficiency is maximized. We illustrate the proposed methods using a study on ammonium nitrogen concentrations from two sites in the Huaihe River in China, where the interest is in quantifying the trend in the most recent years while accounting for possible temporal correlations and “irregular” observations in earlier years.     

Nutrients Availability Shapes Fungal Community Composition and Diversity in the Rare Earth Mine Tailings of Southern Jiangxi,China

Russian Journal of Ecology - The present study characterized the nutrients availability of three rare earth tailings deserted in different time stages in Southern Jiangxi of China, and revealed the...     

Spatial simulation and LCA evaluation on the plastic waste recycling system in Tianjin

With the rapid economic development in China, the amount of plastic waste (PW) generated has greatly increased and much of the waste is currently not treated. To reduce greenhouse gas (GHG) emissions from recycling of PW, we estimated the PW flow and considered methods to improve the household PW recycling system in Tianjin by adjusting processes during transportation and establishing a PW recycling factory in Zi’ya Industrial Park. The goal of the study was to identify reasonable improvements for the recycling system and clarify the environmental load. Geographic information system (GIS) technology was used to simulate transport processes for comparing GHG emissions from the transport processes between the present case and an improved case. Life cycle assessment (LCA) was used to compare GHG emissions between a projected scenario and a baseline scenario. Estimated GHG emissions during transport processes in the improved case were reduced by about 12,197 t CO₂ eq per year compared to the present case, equivalent to about 65.9 % of the total emissions in the present case. GHG emissions in the projected scenario were about 101,738 t CO₂ eq less per year than the baseline scenario, equivalent to about 75.5 % of the total emissions in the baseline scenario.