Effects of amine, amine salt and amide on the behaviour of carbon dioxide absorption into calcium hydroxide suspension to precipitate calcium carbonate

The amount of carbon dioxide （CO2） absorption and calcium ion （Ca^2＋） concentration besides the pH of aqueous solution were observed during the COz absorption to precipitate calcium carbonate （CaCO3） from calcium hydroxide （Ca（OH）2）. A reaction rate-limiting effect of an amount of CO2 absorption without any organic additives in the early stage of the precipitation was observed, which was attributed to an interruption effect of bicarbonate ion （HCO3） on the precipitation of CaCO3. The improvement for the reaction rate was achieved not only by amine additives but also by neutral additives such as ε-caprolactam or amine salt. When the hexamethylene diamine was dissolved in the solution, successive change of crystal forms of CaCO3 aragonite to calcite in aqueous suspensions, confirmed by Ca^2＋ concentration change and X-ray diffraction, was concluded that a local environment around the amine group in aqueous solution and an interaction of the diamine with precipitated CaCO3 particles were important factors for these reactions.     

Effect of six kinds of scale inhibitors on calcium carbonate precipitation in high salinity wastewater at high temperatures

Precipitation of calcium carbonate(Ca CO3) scale on heat transfer surfaces is a serious and expensive problem widely occurring in numerous industrial processes. In this study, we compared the scale inhibition effect of six kinds of commercial scale inhibitors and screened out the best one(scale inhibitor SQ-1211) to investigate its scale inhibition performance in highly saline conditions at high temperature through static scale inhibition tests. The influences of scale inhibitor dosage, temperature, heating time and p H on the inhibition efficiency of the optimal scale inhibitor were investigated. The morphologies and crystal structures of the precipitates were characterized by Scanning Electron Microscopy and X-ray Diffraction analysis. Results showed that the scale inhibition efficiency of the optimal scale inhibitor decreased with the increase of the reaction temperature. When the concentration of Ca2+was 1600 mg/L, the scale inhibition rate could reach 90.7% at 80°C at p H 8. The optimal scale inhibitor could effectively retard scaling at high temperature. In the presence of the optimal scale inhibitor, the main crystal structure of Ca CO3 changed from calcite to aragonite.     

From waste prevention to promotion of material efficiency: change of discourse in the waste policy of Finland

This article analyses the process of preparing the proposal for a new Finnish National Waste Plan (NWP 2007–2016). The focus of this study is on the use of the alternative concepts of waste prevention or material efficiency and on the shift in discourse from the former to the latter concept.The strengths and weaknesses of these competing concepts were analysed using criteria such as synergy, semantic aspects, legal context and applicability to monitoring. The discourse presented by different stakeholder groups was analysed. The implications of choosing either of the concepts were illustrated.The author concludes that waste prevention can be promoted just as well, or even better from the perspective of improving material efficiency. The concept must be complemented by policy instruments within the chemical policy sector to cover the aspect of qualitative waste prevention.     

城市如何可持续发展?——评《绿色城市法则:向可持续发展城市转变》

<正>艾伦·B·雅各布斯认为,城市应该是一个给人提供生活空间的美丽而充满魅力的地方,是社会集体成就的最终体现。在这里,人们可以恣意发挥,最大限度地实现自我价值。自由、爱、创意、激情、平静和欢乐等不同元素在这里交织。——(《美好城市:沉思与遐想》)随着个人对城市生活的向往和社会经济发展的需要,世界正在经历大规模的城镇化进程。2008年,城市人口已经占到总人口的50%;根据第六次全国人口普查,中国在2010年的城市化率也达到了49.7%,并以每年近一个百分点的速度飞快增长。城镇化是21世纪的特征,正在重     

从“治”到“化”的规模化养殖场废物处理的循环经济模式

首先讨论了“治”字思维模式下,我国禽畜养殖业规模化养殖场存在污染物既不经济又不环保的严峻现实问题。事实上,规模化禽畜养殖场产生的“废物”,既是严重的污染源,又是一种必须利用的资源。因此,针对规模化养殖场的污染物“治”字思维问题,在立足于粪便及污水的综合利用100%“资源化”的“化”字思维指导下,遵循循环经济原则,建立无废无污开放式闭合循环的生态经济新模式。一方面,养殖业所有流程按循环利用原则,实行生态工艺或无废工艺的改造;另一方面,在一个大的区域里把畜禽养殖业与其它产业,特别是大农业中的种植业以生态经济循环链锁关系配置成首尾相接的“废料—原料”的循环经济新模式,在达到边际成本最低的同时取得边际效益的最大化。     

Adapting importation policy to global commodity markets: implications of rice import allocation in Singapore

Structural changes in the global commodity markets have particularly serious implications to the food security of import-dependent countries. Adapting importation policy to that global change is essential given that many commodities are imported to fulfill domestic demand. Using Singapore as a case study, this paper examines rice (Oryza) import allocation for seeking adaptive measures, which have broad implications to import-dependent countries. Its quarterly trade data (between 1999 and 2008) have been analyzed using an almost ideal demand system (AIDS) model. Our findings in respect to expenditure elasticity reveal that Singapore will continue its importation from its current range of suppliers, and add new import sources, fulfilling its national diversification strategy. New sources that located in different regions will also strengthen Singapore’s regional diversification strategy. Both national and regional diversification strategies enable any country to tap into associative import sources when unfavorable events deplete supply from a normally preferred supplier. In addition, the results in respect to own-price elasticity suggest that Thailand is Singapore’s primary preferred source while other exporters are secondary suppliers. Supported by the outputs of cross-price elasticity, secondary sources are substitutable. Within a diversified import portfolio, their competitive relationship gives an import-dependent country a strategic position to hedge against price manipulation and escalation, and to substitute expensive suppliers with cheaper alternatives. For these reasons, an import diversification policy is recommended both as an adaptive measure in response to the global change in commodity markets and, at the same time, as a mean for sustaining food security in import-dependent countries.     

From waste hot-pot oil as carbon precursor to development of recyclable attapulgite/carbon composites for wastewater treatment

The utilization of waste products as valuable materials was a technical imperative for waste management. In this study, the cost-effective attapulgite/carbon(APT/C) composite was developed for wastewater treatment using waste hot-pot oil as a carbon precursor through a facile one-step calcination process. The APT/C composite prepared at 300°C exhibited the excellent adsorption capacity and rapid equilibrium rate over a broad p H range for the removal of various pollutants. More importantly, the removal ratios of the composites toward Methyl Violet and tetracycline still remained 77.6% and 60.2% of the initial adsorption capacity after ten adsorption–regeneration cycles via a facile thermal regeneration strategy, respectively.Beyond all doubt, this research provided a feasible and economical way for the sustainable utilization of waste hot-pot oil in wastewater treatment, achieving the concept of disposal waste with waste and recycling.     

A promising niche: waste to energy project in the Indian dairy sector

The dairy sector is known to have significant local and global environmental impacts; but it also has proven renewable-energy generation potential. This paper analyzes a specific niche experiment in the Indian dairy industry, wherein cattle waste management is carried out by a multitude of stakeholders. These include the waste collectors, local technology adopters, research institutions, multilateral donor agencies, the Indian government, technology suppliers and operation and maintenance teams who have managed an uninterrupted 1 MWe energy production over the past 4 years. This analysis uses the sociotechnical regime framework to study the interaction of social, technological, economic and policy-related aspects relevant to the niche experiment. The analysis shows a potential to contribute to the development of two complementing regimes—one related to cooperative waste management and the other related to grid-connected renewable-energy-based electricity generation. Key factors for a successful development are not only a long-term financing protection through government subsidies to cover higher capital cost and a preferential tariff related to energy throughput, but also the adaptation of technology, the embedding in the local cooperative structure and the removal of regulatory barriers.     

Effect of Ca:Mg ratio and high ammoniacal nitrogen on characteristics of struvite precipitated from waste activated sludge digester effluent

This study revealed the relationship between the presence of calcium impurities and ammoniacal nitrogen concentration upon crystallization of struvite. The research hypothesis was that the presence of both calcium and high concentrations of ammoniacal nitrogen(328–1000 mg/L) in waste activated sludge may influence the struvite quality and acid stability. Hence, we studied the impact of Ca:Mg ratio upon morphology, particle size, purity and dissolution of struvite, in the presence of varying levels of excess ammoniacal nitrogen. X-ray diffraction revealed that up to 31.4%amorphous material was made which was assigned to hydroxyapatite. Increasing the ammoniacal nitrogen concentration and elevation of the Mg:Ca ratio maximized the presence of struvite. Struvite particle size was also increased by ammoniacal nitrogen as was twinning of the crystals. Tests with dilute solutions of organic acid revealed the sensitivity of struvite dissolution to the physical characteristics of the struvite. Smaller particles(21.2 μm) dissolved at higher rates than larger particles(35.86 μm). However,struvite dissolved rapidly as the p H was further reduced irrespective of the physical characteristics. Therefore, addition of struvite to low p H soils was not viewed as beneficial in terms of controlled nutrient release. Overall, this study revealed that waste activated sludge effluent with high ammoniacal nitrogen was prospective for synthesis of high quality struvite material.     

A strategy for enhancing anaerobic digestion of waste activated sludge: Driving anodic oxidation by adding nitrate into microbial electrolysis cell

Cathodic reduction of CO₂ and anodic oxidation of organic matters are crucial to methane-producing microbial electrolysis cell (MEC) applied in anaerobic digestion of waste activated sludge. However, cathodic CO₂ reduction is usually restrained by slow metabolism rates of H₂-utilizing methanogens and low electron-capturing capacity of CO₂, which consequently slows down the anodic oxidation that participates to sludge disintegration. Herein, a strategy with adding nitrate as electron acceptor to foster electronic transfer between the anode and cathode was proposed to improve anodic oxidation. Results showed that the average efficiency of anodic oxidation in the nitrate-added MEC increased by 55.9%. Accordingly, volatile suspended solid removal efficiency in the nitrate-added MEC was 21.9% higher than that of control MEC. Although the initial cumulative methane production in the nitrate-added MEC was lower than that of control MEC, the cumulative methane production in 24?days was 8.9% higher. Fourier transform infrared spectroscopy analysis indicated that anodic oxidation of MEC with nitrate accelerated the disintegration of sludge flocs and cell walls. Calculation on current signal further revealed that anodic oxidation driven by cathodic nitrate reduction was the main mechanism responsible for the improved sludge digestion.     

农村生活污水治理:从理论、实践到决策

农村生活污水治理是“十四五”农村人居环境整治提升的突出短板。随着农村生活污水治理理论实践的不断深化,生态处理与资源利用已成为其治理的主导方向。发挥好农村生态系统自我修复能力,实现生活污水就地消纳,为打破“照搬城镇模式”固有思维束缚提供了新思路。本文利用生态学基本原理阐释农村生活污水治理的理论内涵,梳理政策演进和实践探索,提出统筹推进一体化治理、完善设施管理制度体系、力戒工作“形式主义”、推动“政产学研”融合、搭建智慧运维管理平台等对策建议,服务农村生活污水治理决策管理,以期为农村人居环境整治提升行动提供学科支撑。     

The Development of Animal Behavior: From Lorenz to Neural Nets

In the study of behavioral development both causal and functional approaches have been used, and they often overlap. The concept of ontogenetic adaptations suggests that each developmental phase involves unique adaptations to the environment of the developing animal. The functional concept of optimal outbreeding has led to further experimental evidence and theoretical models concerning the role of sexual imprinting in the evolutionary process of sexual selection. From a causal perspective it has been proposed that behavioral ontogeny involves the development of various kinds of perceptual, motor, and central mechanisms and the formation of connections among them. This framework has been tested for a number of complex behavior systems such as hunger and dustbathing. Imprinting is often seen as a model system for behavioral development in general. Recent advances in imprinting research have been the result of an interdisciplinary effort involving ethology, neuroscience, and experimental psychology, with a continual interplay between these approaches. The imprinting results are consistent with Lorenz' early intuitive suggestions and are also reflected in the architecture of recent neural net models.     

From large-scale to micromachining: A review of force prediction models

In this paper, a review of work performed in the area of force modelling in metal cutting processes is presented. Past and present trends are described and criticised to compare their relevance with current requirements. Several approaches are reviewed, such as empirical, mechanistic and analytical models. The models’ ability to predict forces, from rough machining to finish machining, is analysed.     

环境中的轮胎磨损颗粒:从路面到海洋

轮胎磨损颗粒是环境中微塑料的主要来源之一,目前全球轮胎磨损颗粒的释放量在590万t·a^-1左右,约占海洋微塑料总量的15%.轮胎磨损颗粒产生于路面,通过雨水径流迁移,进而存在于路面、土壤、沉积物、水体、生物体等环境介质中.当前轮胎磨损颗粒的检测主要通过检测标记物来实现,因此,标记物的选择是关键.同时,轮胎磨损颗粒会通过吸附和浸出污染物产生污染,对人体和生物体都有一定的健康风险.对于环境中轮胎磨损颗粒的控制,最直接的方式就是在迁移路径中截留轮胎磨损颗粒和加速轮胎磨损颗粒的分解;而改进轮胎配方,降低磨损率可从源头减少轮胎磨损颗粒的释放.目前,人们对轮胎磨损颗粒的认识不足,检测方法还需要完善,其环境行为和风险评价也缺乏相关的研究.获得轮胎磨损颗粒从路面到海洋迁移的规律性认识,对于了解其生态风险和潜在污染问题十分重要.基于此,本文归纳总结了轮胎磨损颗粒的产生、检测方法、环境分布、潜在风险和缓解措施等方面的研究成果,分析了轮胎磨损颗粒研究今后应予以关注的方向.     

Integrating high resolution soil data into federal crop insurance policy: Implications for policy and conservation

Well-designed and executed policies are critical for aligning sustainability incentives and enabling future agricultural productivity growth. In the U.S., government-administered crop insurance is the primary direct mechanism through which agriculture is subsidized and represents over $100 billion in liabilities annually. Despite the importance of soil properties in determining crop yield formation and risk, the Government does not consider any soil information in generating premium rates under the Federal Crop Insurance Program. The purpose of this study is to investigate the potential of integrating high-resolution soil data into modeling of field-level insurance rates in large-scale applications. Here, using the actual distribution of soil quality across crop fields in a high production region, models are developed to incorporate soil data into insurance rates and then evaluated to investigate the magnitude of risk differentials across different soil qualities. These soil-conditioned results were then compared to rates that would have been generated by the Government’s current soil-naïve methodology. This study indicates that the degree to which soils vary within a county is highly significant, leading to rating errors of 200% or greater. Implications of ignoring soil information and operational considerations of modifying this cornerstone program are discussed.     

Contributions to eco-design of machine-to-machine product service systems: the example of waste glass collection

Efficient waste management is necessary in order to face up to increasing quantities of waste generated in modern societies. A technical solution using a Machine-to-Machine (M2M) enhanced Product-Service System (PSS) for bring-in waste glass collection is identified. Methodology based on Life Cycle Analysis (LCA) is proposed. The results help understand the mechanisms of M2M PSS. Possible improvements are explored and the study shows how the PSS infrastructure impacts the environment. It examines the influence of major organisational parameters and contributes to eco-design and dimensioning of the M2M PSS. It reveals the interest of mutualisation to reduce environmental impacts and shows the importance of limiting data exchanges. It argues for the use of multi-criteria LCA on the complete system including the telecom infrastructures and employs realistic use scenarios derived from field studies.     

Human Neuroblastoma: From Basic Science to Clinical Debut of Cellular Oncogenes

MYCN  , which identifies a group of patients who have a particularly dire prognosis. Amplified MYCN is used today as a prognostic marker on which therapy design is based to a large extent. An unusual aspect of neuroblastoma is the high rate at which tumors regress spontaneously, even in infants with extensive liver involvement and numerous subcutaneous nodules. Identifying the molecular and cellular basis of spontaneous regression could result in improved therapeutic approaches. Neuroblastoma is a model tumor with many fascinating aspects but has remained a challenge to the pediatric oncologist