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.     

和田河两支流出山口枯水流量的变化特性分析

利用和田河两支流1957-2010年的逐月实测流量资料,采用滑动平均法、Mann-Kendall秩次相关检验法及小波分析法,分析了和田河出山口枯水流量的变化特征。结果表明:和田河两支流出山口处实测枯水流量在20世纪90年代末之前变化趋势不明显,90年代末之后呈显著增大趋势;但两支流枯水流量均未发生突变现象;两支流枯水流量的周期性均不显著,其中最枯月流量周期性的优势尺度为10¹2 a。分析枯水流量的变化特点,主要与流域气温升高及出山口水库调节有关。     

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.     

Lost carbon emissions: the role of non-manufacturing “other industries” and refining in industrial energy use and carbon emissions in IEA countries

We present a review of trends in energy use and output in branches of industry not often studied in detail: petroleum refining and what we call the other industries — agriculture, mining, and construction. From a sample of IEA countries we analyze eight with the most complete data from the early 1970s to the mid-1990s. We carry out a decomposition analysis of changes in energy use and carbon emissions in the “other industries” sector. We also review briefly the impact of including refining in the evolution of manufacturing energy use, usually studied without refining. Despite many data problems, we present our results as a way of enticing others to study these important “lost” sectors more carefully. We have five basic findings. First, “other industries” tends to be a minor consumer of energy in many countries, but in some, particularly Denmark, the US, and Australia, mining or agriculture can be a major sector too large to be overlooked. Second, refining is an extremely energy intensive industry which despite a relatively low share of value added consumes as much as 20% of final energy use in manufacturing. Third, as a result of a slower decline in the carbon-intensity of these industries vis-à-vis the manufacturing industries, their share of industrial emissions has been rising. Fourth, for other industries variation in per capita output plays a relatively small role in differentiating per capita carbon emissions compared to the impact of subsectoral energy intensities. Finally, including this energy in CO₂ calculations has little impact on overall trends, but does change the magnitude of emissions in most countries significantly. Clearly, these industries provide important opportunities for searching for carbon emissions reductions.     

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.     

Monthly comparative performance of solar stills of various designs

This paper presents design, fabrication details and long term performance of single slope basin-type fifre reinforced plastic (FRP) solar still, double slope basin-type FRP solar still, single slope FRP multiwick solar still, double slope FRP multiwick solar still, single slope FRP multiwick solar distillation plant and double slope FRP multiwick solar distillation plant. On the basis of performance under Delhi Climatic conditions following conclusions were drawn: in winter, the single slope FRP basin-type still gives better yield than the double slope FRP basin-type solar still; in summer the distillate output of the double slope FRP basin-type solar still is greater than that of the single slope FRP basin-type solar still. The same holds good for single and double slope FRP multiwick solar stills and the solar distillation plants     

设计洪水在防洪计算中的误区

在防洪计算中,设计洪水的可靠性直接影响着待建工程的规模大小、安全程度和浪费状况。本文主要阐述了影响设计洪水计算成果的几种误区：一是过多使用人造插补延长资料系列的误区;二是特大洪水插补越多越好的误区;三是面积和河长水文比拟法的选用的误区;四是无连续大洪水发生,设计洪水稳定不变的误区等。并通过对陕西省泾河上的张家山和桃园水文站流量系列进行实例分析,分别验证这四种误区的影响。     

Dual functional application of pomelo peel-derived bio-based carbon with controllable morphologies: An efficient catalyst for triiodide reduction and accelerant for anaerobic digestion

Pomelo peel-derived bio-based carbon with controllable morphologies are successfully prepared by three different methods (microwave pyrolysis, two-step activation, hydrothermal carbonization combining chemical activation). The differences in specific surface area and pore size distribution caused by various morphology features remarkably affect the application potential of as-prepared bio-based carbon. Two-step activation carbonization is proven to be an effective and feasible method to synthesize small-size bio-based carbon with large specific surface area (1377.60 m²/g) and total pore volume (0.72 m³/g) as compared with other methods. The bio-based carbon prepared by two-step activation method as counter electrode catalyst in dye-sensitized solar cell (DSSC) obtains an excellent photovoltaic performance as compared with the Pt-based DSSC (6.94% vs. 6.71%). Furthermore, the as-prepared bio-based carbon is used as accelerant in anaerobic digestion (AD) systems and obtains the enhanced cumulative biogas production (525 mL/g VS) and chemical oxygen demand removal rate (70.95%) as compared with the control check group (296 mL/g VS, 29.55%). This work illustrates three promising methods to prepare bio-based carbon with controllable morphologies and superior surface area for realizing their multifunction resource utilizations in renewable energy fields.     

Hydrogen production from acidogenic food waste fermentation using untreated inoculum: Effect of substrate concentrations

The effect of substrate concentrations (0, 7.5, 15, 22.5, 30, and 37.5 g-VS/L) on hydrogen production from heat-treated and fresh food waste (FW) using untreated inoculums was investigated in this work. The highest hydrogen yield (75.3 mL/g-VS) was obtained with heat-treated FW at 15 g-VS/L. Lower substrate content could not provide enough organic matter for hydrogen fermentation, while higher substrate concentrations shifted the metabolic pathways from hydrogen fermentation to lactic acid fermentation by enriching the lactic acid bacteria (LAB), which lowered the slurry pH and decreased enzyme activity, resulting in a lower chemical oxygen demand (COD), volatile solid (VS), carbohydrate removal rate, and hydrogen yield. Compared with fresh FW, heat-treated FW is preferred for biohydrogen process with acetate as the main organic product. Additionally, at the optimal concentration (15 g-VS/L) using fresh FW, lactic acid is first accumulated and then degraded to produce hydrogen with butyrate as the main metabolite.