生活垃圾焚烧飞灰中重金属浸出影响研究

通过浸出液pH测定、全量测定以及(HJ/T 299-2007)硫酸硝酸法和(HJ/T 300-2007)醋酸缓冲溶液法浸提,对生活垃圾焚烧飞灰中重金属浸出特性进行了实验研究.结果表明浸出pH条件、飞灰中重金属含量以及重金属分布形态是影响浸出浓度的主要因素.相比于硫酸硝酸法,醋酸缓冲溶液法重金属提取效率明显较高,尤其是铜锌镉铬.垃圾焚烧飞灰潜在环境风险较大,在填埋处理及综合利用时应充分考虑其浸出特性.     

Identifying Conservation and Restoration Priorities for Saproxylic and Old-Growth Forest Species: A Case Study in Switzerland

Saproxylic (dead-wood-associated) and old-growth species are among the most threatened species in European forest ecosystems, as they are susceptible to intensive forest management. Identifying areas with particular relevant features of biodiversity is of prime concern when developing species conservation and habitat restoration strategies and in optimizing resource investments. We present an approach to identify regional conservation and restoration priorities even if knowledge on species distribution is weak, such as for saproxylic and old-growth species in Switzerland. Habitat suitability maps were modeled for an expert-based selection of 55 focal species, using an ecological niche factor analyses (ENFA). All the maps were then overlaid, in order to identify potential species’ hotspots for different species groups of the 55 focal species (e.g., birds, fungi, red-listed species). We found that hotspots for various species groups did not correspond. Our results indicate that an approach based on “richness hotspots” may fail to conserve specific species groups. We hence recommend defining a biodiversity conservation strategy prior to implementing conservation/restoration efforts in specific regions. The conservation priority setting of the five biogeographical regions in Switzerland, however, did not differ when different hotspot definitions were applied. This observation emphasizes that the chosen method is robust. Since the ENFA needs only presence data, this species prediction method seems to be useful for any situation where the species distribution is poorly known and/or absence data are lacking. In order to identify priorities for either conservation or restoration efforts, we recommend a method based on presence data only, because absence data may reflect factors unrelated to species presence.     

Valuable utilisation of spray dryer ash and its performance in structural concrete

This paper focuses on the valuable utilisation of spray dryer ash (SDA) and investigates its performance in concrete for structural applications. Based on the challenges associated with the disposal of coal combustion products (including SDA) and the economic costs linked to cement production, this research seeks to provide an environmentally friendly and more cost-effective concrete product by utilising SDA in partial replacement of cement in concrete. With the exception of a relatively high-sulphur content, SDA exhibits very useful properties that are closely related to Class C fly ash and Portland cement.

Experimental tests were carried out to determine the effect of SDA replacement of Portland cement (ranging from 0 to 50% replacement) on the compressive strength, bond strength, freeze-thaw performance and corrosion resistance of concrete. The addition of SDA in non-air entrained concrete provided a general increase in its strength with optimal limits ranging between 25 and 35% replacement. The addition of SDA produced a negligible effect on the freeze-thaw durability of the concrete (air entrained). Results for corrosion performance were not as definitive, but indicate that the use of SDA does not significantly change the likelihood of reinforcing bar corrosion.     

Printed in great Britain Cr(VI) and other metallic mutagens in fly ash and welding fumes†

Particulate samples taken from both the indoor (working) and outdoor (community) environments contain a wide range of metallic trace elements most of which are mutagenic in at least one of the short term tests for genotoxicity currently in use. Because of the demonstrated presence of a short lived biologically active species (Cr(VI)), and the uncertainty with which the results of the screening of metallic compounds in short term tests can be interpreted in terms of human risk, great care must be taken to assure the appropriate collection, storage, and chemical and biological assay of such material. The sensitivity of the results for fly ash and welding fumes to variations in these protocols is demonstrated and discussed.     

The Reuse of Urban and Industrial Waste in Tai-Lin-Pu Reclamation Project,Taiwan

Abstract

This study introduces the principles of KMG's (Kaoshiung Municipal Government) dealing with the non-poisonous urban and industrial waste through reclamation of shore land in reinforcing a sense of coastal protection and land development in Tai-Lin-Pu coastal area, southern Taiwan.

Through a series of experimental studies, we found that substitutes of coarse aggregate with a broad spectrum of integrating slag powder, fly ash, and cementitious material can be obtained with a benefit up to 80% saving of cement. the integrated aggregates from the non-poisonous industrial wastes were subsequently made into armour units and used in the field tests at Tai-Lin-Pu coastal area, where the shorelines are seriously eroded. After being subjected to several severe typhoon advents, the results showed that the waste-made units used as the protection breakwater, together with construction wastes and excavated soil as the filling material, prove to be an effective practice in utilizing recycled urban waste to reclaim erosive shore lands. Moreover, this study also demonstrates that through detailed analysis of the waste characteristics, scrap material could be turned into valuable construction aggregates, and highlights the value of non-poisonous urban and industrial waste as a alternative resource for the shore protection engineering.     

Leaching of trace and major elements from coal ash dumps

Coal ash samples taken from an active, currently filled cassette as well as samples taken from passive cassettes of the power plant in Obrenovac (Yugoslavia) were subjected to sequential leaching, comprising of extraction with distilled water, 1 M KC1 and 0.1 M HC1. Concentrations of trace and major elements found in extracts revealed that lead and cadmium are not present in significant concentrations, while other elements show different behavior: practically all absorbed trace elements and most of the major elements are partially leached during transport, while later, on the dump, only a slow release of most of the examined ion‐exchangeable elements occurs.     

Durability of conventional concretes containing black rice husk ash

In this study, black rice husk ash (BRHA) from a rice mill in Thailand was ground and used as a partial cement replacement. The durability of conventional concretes with high water–binder ratios was investigated including drying shrinkage, autogenous shrinkage, depth of carbonation, and weight loss of concretes exposed to hydrochloric (HCl) and sulfuric (H₂SO₄) acid attacks. Two different replacement percentages of cement by BRHA, 20% and 40%, and three different water–binder ratios (0.6, 0.7 and 0.8) were used. The ratios of paste volume to void content of the compacted aggregate (γ) were 1.2, 1.4, and 1.6. As a result, when increasing the percentage replacement of BRHA, the drying shrinkage and depth of carbonation reaction of concretes increased. However, the BRHA provides a positive effect on the autogenous shrinkage and weight loss of concretes exposed to hydrochloric and sulfuric acid attacks. In addition, the resistance to acid attack was directly varied with the (SiO₂ + Al₂O₃ + Fe₂O₃)/CaO ratio. Results show that ground BRHA can be applied as a pozzolanic material and also improve the durability of concrete.     

醇酸清漆对典型装饰木材燃烧特性和生烟特性的影响

为了探讨醇酸清漆对典型装饰木材火灾危险性的影响,利用热重分析、差热分析、木垛法、隧道法和塑料烟密度仪对装饰木材的燃烧性能、热解特性和生烟特性进行了分析。结果表明,木材及其表面涂覆的醇酸清漆主要热失重发生在200~500℃,其中木材的热解过程为先吸热、后放热的过程,而醇酸清漆为吸热过程。与未涂覆清漆的木材相比,清漆使木材在燃烧过程中质量损失、有焰燃烧时间及火焰传播比值明显增加。同时,醇酸清漆的烯烃结构和苯环结构还导致木材的比光密度、质量光密度增大,烟气危害增大,从而进一步增大了火灾危险性。此外,装饰木材的生烟特性还受火焰条件和辐射功率的影响,高辐射功率和有焰条件下材料的比光密度和质量光密度均较低。     

重庆金佛山降雪中飞灰单颗粒特征及来源解析

大气降雪能够保存大气环境信息,是研究区域环境的良好介质.位于渝黔交接带的金佛山海拔2 251.1 m,冬季降水以降雪的形式出现,周边区域人类活动强烈.关于该区域大气气溶胶中的飞灰单颗粒特征的研究比较缺乏.本研究采集了金佛山5个降雪样品,运用扫描电镜及X能谱分析联用系统(SEM-EDS)对样品中的132个飞灰进行单颗粒形貌、化学组成分析.结果表明,研究区降雪中存在大量球形飞灰,包含光滑颗粒、粗糙颗粒及聚合体颗粒3种形态,分别占统计颗粒的80.31%、14.39%和5.30%;平均粒径1.64μm,平均环度1.09.按主导化学元素分为富硅类、富碳类、富铁类、富铝类及富钛类5种,所占比例分别为34.09%、49.24%、12.88%、2.27%和1.52%.结合气象资料、气团后向运移轨迹和飞灰性质,推测富碳类飞灰可能主要来自于生活排放源和工业活动;富硅类飞灰可能来自于渝西、黔北、湘中、浙赣一带及粤西的火力发电厂等高温燃煤工业;富铁类及富钛类飞灰则可能来源于渝西和黔北、湘中的钢铁厂、轧钢厂等金属冶炼活动.     

Evaluation of beech for production of bio-char,bio-oil and gaseous materials

Evaluation of Oriental beech (Fagus orientalis L.) was investigated with aspect of thermo-chemical conversion to obtain bio-char, bio-oil and gaseous. When the pyrolysis temperature increased, the bio-char yield decreased. A high temperature and smaller particles increase the heating rate resulting in a decreased bio-char yield. The bio-char obtained are carbon rich, with high heating value and relatively pollution-free potential solid biofuel. The liquefaction yield sharply increased with increasing the temperature near critical temperature and after that. In the pyrolysis, increases of liquid yields are considerably sharply for all of the samples with increasing of pyrolysis temperature from 690 K to 720 K. The beechnut oil was converted to biodiesel in supercritical methanol without using the catalyst. Experiments have been carried out in an autoclave at 493, 523 and 593 K, and with molar ratios of 1:6–1:40 of the oil to methanol. The yield of alkyl ester increased with increasing the molar ratio of oil to alcohol.