空分装置预冷系统冷冻水改造

由于夏季循环水系统水温高,以及溴化锂冷水机组制冷效果差,空冷塔出口温度超标,影响空分装置的稳定运行。利用低温、洁净的低压生产消防水替代进入空冷塔上部的冷冻水,降低了分子筛吸附器入口温度,保证了系统的稳定运行,同时降低了运行成本和检维修费用。

颠簸状态下制冷系统气液分离器性能的影响研究

主要针对混合工质两级喷射制冷系统在船舶出海条件下的运行稳定性进行了分析研究。气液分离器是喷射式制冷系统中一个较为重要的设备部件。内部液体的波动与飞溅,容易使得气液分离器出现出气带液的现象,而高压级喷射器引射的出气带液量对整个系统的工作性能会有一定的影响。本文通过数值模拟与试验研究的方法对系统中的气液分离器进行了研究,结果表明,25cm为内部最大安全液位。当分离器内部液位高于25 cm时,气液分离器的出气带液量会随着内部液面高度的上升而增加。另外,在分离器中增设挡板对内部液体的波动与飞溅有明显的抑制作用。

Electrocatalytic generation of reactive species and implications in microbial inactivation

Controlling microbial proliferation in water systems,including wastewater,recreational water,and drinking water,is essential to societal health.Microbial inactivation through electrochemically generated reactive species(RS)mediated pathways provides an effective route toward this microbial control.Herein we provide an overview of recent progress toward electrocatalytic generation of RS and their application in water disinfection,with a focus on the selective production of RS,the microorganism interactions with RS(including both RS mechanisms of action and innate microorganism responses to RS),and practical implementation of electrochemically generated RS for microbial inactivation.The article is concluded with a perspective where the challenges and opportunities of RS‐based electrochemical disinfection of water are highlighted,along with possible future research directions.

Ecological Footprint Dynamics of Yunnan, China

A fundamental element of sustainable development is that humans live within nature's biological capacity. Quantifying this, however, remains a significant challenge for which there are many emerging tools. The concept of the Ecological Footprint is one such accounting tool for comprehensive assessment of the status of sustainable development, based on integration of resource consumption and land capacity, reflecting the human impact on the environment. A region's development is defined as unsustainable when the Ecological Footprint surpasses the biological capacity. In this paper, the Ecological Footprint concept was applied in assessing the development of Yunnan Province, China in a period between 1988 and 2006. The results showed that the Ecological Footprint per capita in Yunnan rose from 0.854 gha in 1988 to 2.11 gha in 2006. Ecological deficit, defined as when the human demand on the land surpasses the regions biological productive capacity, emerged in 1991 and quickly increased from 0.02 gha in 1991 to 1.05 gha in 2006. The increase in the ecological deficit is primarily a result of the rapid increase in population and consumption level. To achieve sustainable development in Yunnan, production and consumption rates need to be modified.

Kinetics of Treated Domestic Sewage Disinfection through Catalytic Oxidation with H2O2

The inactivation of bacterial cells through catalyzed oxidation using hydrogen peroxide as the primary oxidant agent is dependent on a series of factors, such as the concentration of the catalyst, the rate of hydroxyl radical formation in the controlled decomposition of the oxidant agent, and the concentration and toxicity of hydrogen peroxide. The objective of this study was to develop a mathematical model able to predict the kinetics of the inactivation Escherichia coli and total coliforms cells present in treated domestic sewage through catalytic peroxidation. The catalyst used was iron oxide supported on mineral coal （called CP）, and the effects of the operational conditions, including hydrogen peroxide concentration and dosage of catalyst, were evaluated. The results showed that the disinfection kinetics of the treated domestic sewage is dependent on the concentrations of hydrogen peroxide and catalyst dosage. The kinetic model was shown to be able to predict the behavior of the inactivation kinetics of the bacterium Escherichia coli ATCC-25922 when different concentrations of hydrogen peroxide （75 and 100 mg·L^-1） were used, regardless of the catalyst dosage.

One Year Minergie-A--Switzerlands Big Step towards Net ZEB

The first available label standardizing a zero-balanced type of building is the Swiss Standard Minergie-A. The standard prescribes an annual net zero primary energy balance for heating, domestic hot water and ventilation. Electricity consumption for appliances and lighting is excluded. Additionally, Minergie-A is the first standard worldwide which includes a requirement in regard to embodied energy. Based on an analysis of 39 Minergie-A buildings, this paper shows that a wide range of different energy concepts and embodied energy strategies are possible in the scope of the label. The basis of all Minergie-A buildings is a well-insulated building envelope. However, the step from the Swiss Standard Minergie-A to a Net ZEB （net zero energy building） standard which includes electricity consumption for appliances and lighting is not a very big one. Increasing the size of the photovoltaic system is sufficient in most cases. Anyway, some of the Minergie-A buildings evaluated are also Net ZEBs. In this paper, it is also shown that the net zero balance during the operational phase of Net ZEBs clearly outweighs the increased embodied energy for additional materials in a life cycle energy analysis.

Enhancing Biogas Production from Anaerobically Digested Wheat Straw Through Ammonia Pretreatment

Aqueous ammonia was used to pretreat wheat straw to improve biodegradability and provide nitrogen source for enhancing biogas production. Three doses of ammonia(2%, 4%, and 6%, dry matter) and three moisture contents(30%, 60%, and 80%, dry matter) were applied to pretreat wheat straw for 7 days. The pretreated wheat straws were anaerobically digested at three loading rates(50, 65, and 80 g·L-1) to produce biogas. The results indicated that the wheat straw pretreated with 80% moisture content and 4% ammonia achieved the highest methane yield of 199.7 ml·g-1(based on per unit volatile solids loaded), with shorter digestion time(T80) of 25 days at the loading rate of 65 g·L-1compared to untreated one. The main chemical compositions of wheat straw were also analyzed. The cellulose and hemicellulose contents were decomposed by 2%-20% and 26%-42%, respectively,while the lignin content was hardly removed, cold-water and hot-water extracts were increased by 4%-44%, and12%-52%, respectively, for the ammonia-pretreated wheat straws at different moisture contents. The appropriate C/N ratio and decomposition of original chemical compositions into relatively readily biodegradable substances will improve the biodegradability and biogas yield.

Dynamics of Lumber Production from Buttressed-Stumps of Logging Residues Using a Fuel Powered Horizontal Mobile Bandsaw Machine

Logging residue can be defined as any form of wood, which under the highest stage of technological development could be used in manufacturing but is left in the forest during logging. Lumber production from logging residues of a previous logging activity by a timber firm was undertaken with the objective of determining the suitability of utilizing buttressed-stumps as raw material for the timber industry. A horizontal mobile bandsaw machine was used to process the buttressed-stumps into lumber. The machine was characterized by a thin-kerr sawing technology （kerf-width 1.6 mm） compared to the conventional bandsaw machines of kerr-widths ranging from 3.0-4.5 mm. Lumber value and volume yields, fuel consumption rate, frequency of tool replacement and lumber production rate were assessed. Results indicated that there is the potential to increase timber production from logging residues by utilizing buttressed-stumps. Lumber value and volume yields of eight timber species investigated in this study ranged from 5%-31% and 34%-54% respectively. Fuel consumption rate which increased with increasing wood density, ranged from 5-14.5 liters/m3 of lumber produced. Frequency of saw replacement increased with increasing wood density. The number of saws required to produce one cubic meter of lumber, ranged from 1 to 7. Lumber production rate ranged from 0.10-0.38 m3/hour, increasing with decreasing wood density.

Sustainability Aspects of the Wheat Sector

In the frame of the present study, we examined the wheat sector with respect to economic and social sustainability. Accordingly, two research questions were formulated： （1） Is wheat production sustainable in economic terms？ and （2） Is wheat production sustainable in social terms？ Our view is that the content of sustainability can be defined on a case-by-case basis, and in our case, wheat production provides this content. To answer the research questions, we collected statistical data on the production area, average yield, production volume, selling price, consumption of wheat, and evaluated the tendencies prevalent in the sector. We suppose that in social terms, sustainability means maintaining consumption at least at a constant level, knowing that this sector produces considerable share of the direct and indirect food raw materials. A chief dilemma is that world population is continuously growing, although the size of the cultivated area in the wheat sector has not indicated significant changes over the past few decades. Unless increasing the yields, severe decrease may occur in the per capita production of wheat in the long run. In this case, the current consumption level will not be sustainable in the medium run. In addition, in the long run, it may even have influence on the consumption level of other commodities.

Advances in Energy-Producing Anaerobic Biotechnologies for Municipal Wastewater Treatment

Municipal wastewater treatment has long been known as a high-cost and energy-intensive process that destroys most of the energy-containing molecules by spending energy and that leaves little energy and few nutrients available for reuse, Over the past few years, some wastewater treatment plants have tried to revamp themselves as ＂resource factories,＂ enabled by new technologies and the upgrading of old technologies. In particular, there is an renewed interest in anaerobic biotechnologies, which can convert organic matter into usable energy and preserve nutrients for potential reuse. However, considerable technological and economic limitations still exist. Here, we provide an overview of recent advances in several cutting-edge anaerobic biotechnologies for wastewater treatment, including enhanced side- stream anaerobic sludge digestion, anaerobic membrane bioreactors, and microbial electrochemical systems, and discuss future challenges and opportunities for their applications. This review is intended to provide useful information to guide the future design and optimization of municipal wastewater treatment processes.

The Necessity for Revising Energy Consumption and Ways to Reduce It in Cement Industry

The increasing growth of energy consumption and the limited fossil energy resources, as the main source of energy in Iran and other parts of the world, has persuaded the industrial societies to struggle more for supplying their needed energy at present and in future. More than 26% of energy in Iran is consumed by industry sector, in which cement section is an important subsectors highly depending on energy. Cement section is so dependent on energy, that more 15% of the related energy is consumed in this section, and its present conditions of energy consumption need a serious revision. Production management, changing the ingredients, finding alternative energy strategies, and importing modem technologies can result in reduction of energy consumption in this section. In this study, while investigating energy consumption of various machineries in the form of electricity and heat in a cement factory, the authors have studied the strategies for decreasing energy consumption in every stage of the production process. Recent studies in the field of cement industry are indicative of recent changes in production methods with priority of reducing energy consumption. Among these changes, we can refer to replacing wet method by dry method, or developing pre-heating center and pre-calcinators. In cement industry, nowadays, not only there is an emphasis on controlling the energy consumption for lower production costs, but as production of every 1 kg of cement gives out more than 0.7 kg CO2 and other pollution particles, environmental issues are also seriously considered. Therefore, if we use alternative fuels with less carbon in their structural formula, besides decreasing energy consumption and costs, there will be less pollutions in the environment as well.

Regional Land Use Patterns and Water Consumption in the Jordan Valley Using Geographic Information Systems

Trends in land use and water consumption are crucial components in understanding the changing nature of agricultural production and water use in- the Northern Jordan Valley. The objective of this study is to examine current agricultural land uses in the Jordan Valley and their water consumption patterns as well as to examine the changes in land use and water consumption that occurred between the years 2002 and 2010. Farm level cropping patterns and total annual water use were analysed in order to examine inter-basin land use and water consumption characteristics as well as to estimate the amount of water consumed by each respective crop in total and per unit of land devoted to its production. It was found that citrus production dominated both land and water usage in every basin of the Northern Jordan Valley and that between 2002 and 2010 there were shifts toward increasing citrus production in almost every basin surveyed. It was found that agricultural irrigation water usage decreased overall between 2002 and 2010 by approximately 15 percent and irrigated land usage in the Jordan Valley increased by 5 percent. The role of citrus farming is becoming more important in the Jordan Valley as Jordan＇s agricultural economy shifts away from subsistence farming for staple food crops like wheat and vegetables toward more financially lucrative crops grown for an increasingly international market. This trend is at least partly due to the increasing cost of agricultural irrigation water from Jordan＇s national canal system.

UV disinfection of Staphylococcus aureus in ballast water: Effect of growth phase on the disinfection kinetics and the mechanization at molecular level

This work aimed to study the inactivate kinetics of Staphylococcus aureus （S. aureus） in artificial seawater by ultraviolet radi- ation, establish relationships between model parameters and growth phases, and explain the mechanization of UV disinfection by molecular biological detection. Investigations were carried out for the validation of Chick-Watson, Collins-Selleck, Horn and Biphasic models when S. aureus was in stationary phase （t=14 h）. The results showed that the Biphasic kinetic model＇s R2 turned out to be the highest one （R2=0.9892） and RMSE was less than 0.5 （RMSE =0.2699）. The Biphasic kinetic model was better fit for ultraviolet disinfection than the other three models under the circumstance of this experiment and chosen to fit the ultraviolet disinfection curves for microorganisms at three growth phases. The sensitivity of microorganisms under ultraviolet radiation was in the following order： in exponential phase 〉 in stationary phase 〉 in lag phase by comparing the indexes of the Biphasic model （kl and x）. Besides, agarose gel electrophoresis was used in order to directly assess the damage to DNA of mi- croorganisms that were exposed to the different dose of UV irradiation. The results revealed that DNA damage caused by UV radiation was an important reason for the microorganism inactivation and as the UV dose increased, there was greater damage caused in DNA.

Effect of pipe material and low level disinfectants on biofilm development in a simulated drinking water distribution system

The efficiency of chlorine and chloramines disinfection on biofilm development in a simulated drinking water distribution system was investigated by using heterotrophic bacterial spread plate technique. The experiments were carried out with four annular reactors (ARs) with stainless steel (SS) or copper (Cu) material slides. The results showed that there were fewer bacteria attached to Cu slides without a disinfectant compared with those attached to SS slides. When the water was disinfected with chloramines, the heterotrophic plate counts (HPCs) on the biofilm attached to the Cu slides were significantly lower (by 3.46 log CFU/cm2) than those attached to the SS slides. Likewise, the biofilm HPC numbers on the Cu slides were slightly lower (by 1.19 log CFU/cm2) than those on the SS slides disinfected with chlorine. In a quasi-steady state, the HPC levels on Cu slides can be reduced to 3.0 log CFU/cm2 with chlorine and to about 0.9 log CFU/cm2 with chloramines. The addition of chloramines resulted in a more efficient reduction of biofilm heterotrophic bacteria than did chlorine. We concluded that the chlorine and chloramines levels usually employed in water distribution system were not sufficient to prevent the growth and development of microbial biofilm. The combination of copper pipe slides and chloramines as the disinfectant was the most efficient combination to bring about diminished bacterial levels.