NOx reburning in oxy-fuel combustion: A comparison between solid and gaseous fuels

In the development of oxy-fuel combustion, reburning of nitrogen oxides, recycled with the flue gases, has been investigated for primary NO_x control. Reduction of between 50 and 80% of the recycled nitrogen oxides has been measured. The present work evaluates the performance of gaseous and solid fuels as agents for reduction of nitrogen oxides by comparing experimental and modelling work performed at Chalmers University of Technology with different fuels. It is shown that the reduction is similar during propane and lignite firing, but that the lignite has slightly higher reduction efficiency. Differences in combustion temperature and heterogeneous effects are possible explanations.     

Treatment-oriented characterization of dry scrubber residue from municipal solid waste incineration

 Dry scrubber residue from municipal solid waste incineration (MSWI) was characterized to identify critical inorganic pollutants and to suggest a conceptual treatment method. The key methods used were thermal analysis, including thermogravimetry (TG) and differential thermal analysis (DTA), pH_stat titration, qualitative X-ray diffraction (XRD), scanning electron microscopy (SEM), chemical equilibrium calculations, and statistics such as error propagation, principal component analysis (PCA), and empirical modeling based on factorial designs. Based on EU directives, the major inorganic pollutants Cd, Cr, Pb, and Zn were found. In addition, the pH was too high. With dry scrubber residue stabilization in mind, the impact of carbonation and hydration was assessed and judged to be encouraging. In particular, chemical equilibrium calculations showed that carbonation has considerable potential to lower the pH and the availability of Pb, Zn, and Cr. The impact of carbonation on the mobility of Cd was found to be small. During carbonation, a metal-trapping calcium aluminosilicate hydrate (C–A–S–H) phase is also formed. Both processes together have the potential to lead to a robust, reliable, and reasonable stabilization method for dry scrubber residue. However, to control these processes, the decisive factors need to be identified and their effects need to be quantified. Ca, Cl, Na, and K might be abundant components which would be mobile even after stabilization. Received: September 11, 2001 / Accepted: December 6, 2001     

Point- and nonpoint-source pesticide contamination in the Zwester Ohm catchment, Germany

Reducing pesticide loads in surface waters implies identifying the pathways responsible for the pollution. The current study documents the pesticide contamination of the river Zwester Ohm, a 4917-ha catchment in Germany with 41% of the land used for crop production. Discharges and concentrations of 19 pesticides were measured continuously at three locations for 15 mo. The load detected at the outlet of the catchment amounted to 9048 g a.i. The losses represent 0.22% of the pesticides applied by the farmers. The contamination showed a seasonal pattern following the pesticide application times. The wastewater treatment plant system (WWTPS) in the catchment (two wastewater treatment plants [WWTP], 14 combined sewer overflows (CSO), four CSO tanks) emits during dry weather periods purified sewage and during storm events sewage mixed with stormwater runoff into the river. The contribution by the WWTPS to the pesticide load was defined as point-source pollution (PSP). The load was dominated by PSP with at least 77% of the total pollution. No significant interdependencies between intrinsic properties of the pesticides, hydrometeorological factors, and the loads occurring in the stream could be found. Therefore, it is not possible to predict PSP for other catchments based on the results from this study. Whereas 65% of the total load entered the river via the WWTP, a portion of 12% was attributed to the CSO. The study points out that the influence of CSO on PSP should be taken into account in future catchment studies in areas with comparable agricultural structure.     

可持续建筑部门的理念与手段

本文概览了伍珀塔尔研究所为建筑部门确立可持续性目标,以及为实现这些目标开创途径所采取的多种方法.资源生产力是覆盖建筑物整个生命周期的考虑(MIPS).为了迈向更大的可持续性,COMPASS理念把单一公司或工业部门的环境、经济和社会各方面因素综合考虑.这些方法中的每一种都有所作为,再根据不同类型的研究,为公司和政策制定者提出建议.多边利益相关者程序可以用来推动建筑部门的全面可持续发展,最终把相关的理念明确地推进到微型和中等级别上.     

Investment in territorial defence depends on rearing environment in brown trout (Salmo trutta)

In many animals, territoriality will arise or cease depending on environmental factors such as intruder rate and resource availability. We investigated the effect of rearing environment on territorial behaviour in ~1.5-month-old brown trout. In the laboratory, wild-caught (reared at a low density) and hatchery-reared (high density) trout were allowed to defend a territory against a size-matched intruder reared in the same or the other environment. Because territorial behaviour should be relaxed at high-rearing densities, we hypothesized that hatchery-reared trout should value their territories less and therefore invest less in defence compared with wild-caught trout. However, in all cases, territory owners were more likely to win the contest and hatchery-reared trout were just as likely as wild-reared to win mixed contests. Furthermore, pairs of hatchery-reared trout initiated contests sooner, fought longer and were more aggressive during the contest compared with pairs of wild trout. When hatchery-reared owners met wild intruders, the contest ended sooner compared with when the roles were reversed. We conclude that territorial behaviour in brown trout is largely innate, but that the hatchery environment has promoted more aggressive individuals. These results suggest that hatchery-reared trout invest more time and energy to obtain the same contest success as wild trout. In conclusion, the lack of experience of territorial defence in a high-density rearing environment seems to reduce the efficiency of territorial behaviour. In turn, this may have negative consequences for the performance of released hatchery fish in the wild.     

Polychlorierte Naphthaline

Measurements show that PCN may occur in industrial waste and residues in the mg/kg range. Investigations were carried out with optimized parameters for GC and MS using two different GC/MS-systems. Chromatograms were obtained for a variety of chlorination degrees using capillary columns of different polarities. It is proposed to quantify PCN using relevant single compounds comparable to the analysis of polychlorinated biphenyls.     

Possibilities for improving nitrogen use from organic materials in agricultural cropping systems

Nitrogen release from organic nutrient sources in soil is influenced by a range of factors such as soil temperature and moisture, and chemical composition of the organic material. Chemical composition can, to a certain degree, be controlled to increase the synchronization of nitrogen (N) release with plant N demand, whereas climatic factors cannot be controlled and so must be taken into account when planning management measures. In this paper, we discuss different ways to affect N release through manipulation of the chemical composition of fresh or pretreated plant materials and animal manures, timing of incorporation, and intentional distribution during application. We conclude by giving an overview of off-farm options that may need to be implemented to achieve improved use of N, especially in agricultural systems with surplus N.     

Trends of air pollution in the Fichtelgebirge Mountains, Bavaria

We analyzed 13 years of hourly measurements of SO₂, NO_x, and O₃, at forest ecosystem research sites in SE Germany. A quasi-continuous data record was obtained by combining data sets from two locations. Before interpreting trends in the combined data set, we analyzed if the change of location introduced a systematic bias. We employed autocorrelation functions, Hurst statistics, complexity analysis, and recurrence quantification and found that the partial data sets exhibited no indication of the presence of any bias. For SO₂, we also compared the data from the forest sites with data obtained in nearby cities and also found no indications for any systematic effects. Applying nonparametric trend statistics we found a significant decrease of the SO₂. Most of the observed decrease is due to the reductions of SO₂ emissions in eastern Germany, but reductions in western Germany and the Czech Republic also played important roles. For O₃, we observed a significant increase, the causes of which are unclear from our data alone. No trend was identified for NO_x.