Membrane bioreactor with nonwoven fabrics as solid–liquid separation media for wastewater treatment

A nonwoven fabric module was utilized as a solid–liquid separation medium in a membrane bioreactor (MBR) for treating wastewater. The experimental results indicated that nonwoven fabrics had lower filtration resistance than microporous membranes in MBR applications. The optimal aeration intensity was approximately 0.01m³/m² s. The effect of mixed liquor suspended solid concentration on filtration resistance was not significant at an operating flux of under 0.8m³/m² d in the study range. The performance of nonwoven fabrics in a MBR application was further demonstrated in a pilot test. Chemical oxygen demand (COD) and suspended solids (SS) in the effluent were maintained under 60 and 10 mg/L, respectively, whereas influent COD varied from 800 to 1800mg/L. The transmembrane pressure was maintained below 5 kPa at a permeation flux of 0.18m³/m² d. The experimental results demonstrated that nonwoven fabrics maintained stable operation in MBR applications under appropriate operating conditions.     

灰色线性回归组合模型在计算给水管道阻力系数中的应用

为了求解管道阻力系数,将其应用到工程中的水力计算中,运用灰色线性回归组合模型进行求解,得出了计算管道阻力系数的数学模型,并结合工程实例进行验证.实践表明该模型的精度较高,具有一定参考价值.     

基于中位数众数理论的Tennant法改进与应用

在河流生态径流计算中Tennant法应用比较广泛,但其多年平均流量的确定一直是该方法应用的一个难点,以往使用的平均数有时并不能准确反映总体分布的集中趋势,针对这一问题,通过研究实测数据的统计特性,引入中位数及众数理论,对原Tennant法进行改进,有效的去除了极端数据对统计规律的影响,找出了典型流量过程。将其应用在滦河下游生态径流计算中,通过新老方法的比较,认为采用改进后的计算方法得到的结果更加科学合理。该方法具有原理简单、计算过程“透明”等特点,对河流生态环境研究和水资源合理利用具有指导意义。     

Effects of size and autoclavation of fruit and vegetable wastes on biohydrogen production by dark dry anaerobic fermentation under mesophilic condition

Fermentative hydrogen production from fruit and vegetable wastes (FVWs) through Dry Fermentation Technology (DFT) was studied through three independent experiments in order to find out the effect of particle size and autoclaving pretreatment on bio-hydrogen production from FVWs and as follows: (1) autoclaved FVWs with sizes < 5 cm (experiment I); (2) raw FVWs with sizes < 5 cm (experiment II) and (3) autoclaved FVWs with sizes > 5 cm (experiment III). The assay with autoclaved waste yielded a higher percentage of hydrogen in the headspace of the dry fermenter reaching a maximum value of 44% in experiment I. However, the maximum hydrogen production was obtained in experiment III with 14573 NmL at a yield of 23.53 NmL H₂/gVS. Profiling of the microbial communities by denaturing gradient gel electrophoresis (DGGE) indicated that the most prominent species were the genera Clostridium, Bifidobacterium, and Lactobacillus.     

水资源问题安全化

水资源安全已成为人们关注的核心。提出了水资源安全的定义与研究内容,对水资源安全的性态进行了研究。指出水资源安全系统具有利己性、针对性和公共性。明确了水资源安全的目标,介绍了水资源安全评价的理论与方法。建立了水资源安全评价指标体系,对山西各地市的水资源安全状况进行了评价,提出了相应的建议。     

Experimental Study on Slope Runoff,Erosion and Sediment under Different Vegetation Types

The relationships between precipitation, vegetation and erosion are important yet unresolved issues in the field of earth surface processes. Vegetation plays an important role in controlling soil erosion. Through field simulated rainfall experiments, we analyzed the characteristics, regulation of, and correlation among the slope rainfall-infiltration-runoff, erosion and sediment under different vegetation types. The results showed that the forest effectively improved soil structure, had stronger runoff and sediment regulation and was influenced less by rainfall intensity than those under other vegetative conditions. In addition, the efficiency and pattern of the regulation of runoff and sediment varied with vegetation types as did the mechanism of action. The soil and water conservation function of forest was water storage and sediment reduction by plant root systems to reduce erosion power, increase infiltration, decrease runoff and reduce flow speed. The function of grassland was direct sediment interception based on surface vegetation canopy for runoff and sediment regulation. The root contribution to runoff and sediment reduction was relatively greater than the shoot contribution under forest conditions, whereas, the effect of shoots and roots on soil loss was almost equivalent under grassland conditions. The different spatial structures of vegetation affected runoff and sediment regulation in different ways, and plant root systems were crucial for soil and water conservation. The cumulative sediment yield of the slopes increased as a statistically significant power function of cumulative runoff. The coefficient and curve shape of function were dependent on vegetation type, soil properties, rainfall intensity and surface roughness. The process of slope runoff and sediment was divided into development, active and stable stages. These stages correlated with each other to constitute a complete rainfall-runoff and erosion-sediment process, which exhibited their own features at each stage. This study furthers understanding of the relationships between vegetation, soil erosion and precipitation.     

发泡剂对水泥宏观发泡效果的试验研究

在室内水泥和发泡剂按不同配比试验的基础上,测出水泥和发泡剂混合物样品的湿重量和干重量,通过分析得出三种发泡剂占水泥质量的含量由2‰、2.5‰、3‰、3.5‰、4‰、4.5‰、5‰变化时对复合硅酸盐水泥与普通硅酸盐水泥发泡效果的规律。研究结果为在减轻边坡植生用客土的重量选择水泥及水泥和发泡剂最佳配比时提供重要参数。     

改进的集对分析水质综合评价方法

针对标准集对分析存在的同异反评语细化问题,利用原创联系度可展性对其进行改进,并建立了地表水水质评价模型,可以得到评价样本对于各水质评价等级的优劣趋同程度。并与模糊评价相结合应用于山西省地表水质评价,并引入差异系数来优化评价指标体系,利用熵权系数法和超标倍数赋权法求得指标的综合权重。将评价结果与灰色聚类法、综合指标法、模糊神经网络法和投影寻踪法的评价结果进行比较,结果表明：改进后的的集对分析评价结果更贴近实际情况,为水环境分析提供了一种更为科学、合理的评价和决策方法,具有良好的应用前景。     

西安市皂河流域降雨径流估算及其特性分析

在皂河无实测流量资料的情况下,为了分析其径流特性,首先应用径流系数法由降雨资料推求流域径流量,进而对求得的径流序列趋势、周期、持续及突变等特性加以分析.结果表明:年径流序列变化表现为不显著的下降趋势;存在3 a、6 a和17 a的准周期;具有Hurst效应;年径流序列在1976,1985年和2006年发生了突变.     

Carbon mitigation in the electric power sector under cap-and-trade and renewables policies

In Europe, CO₂ emissions from the electric power sector and energy intensive industries are capped under a cap-and-trade system (i.e., the EU ETS). When other indirect measures are taken to impact emissions in a specific sector under the cap (such as a push for renewables in the electric power sector), this has implications on the overall allowance price, and on CO₂ emissions both from this specific sector and the other sectors under the cap. The central contribution of this paper is the derivation of impact curves, which describe these interactions, i.e., the impact on allowance price and the shift of emissions across sectors. From a set of detailed simulations of the electric power system operation, a so-called “emission plane” is obtained, from which impact curves can be derived. Focus is on interactions between CO₂ abatement through fuel switching and measures affecting the residual electricity demand (such as deployment of renewables) in the electric power sector, as well as on interactions with other sectors, both in a short-term framework. A case study for Central-Western Europe is presented. The analysis reveals a substantial impact of renewables on CO₂ emissions, and hence on emissions shifts across sectors and/or on the CO₂ price.