Dehalogenation potential of municipal waste incineration fly ash

BACKGROUND, AIMS AND SCOPE: It is well known that the fly ash from filters of municipal waste incinerators (MWI-FA) shows dehalogenation properties after heating it to 240-450 degrees C. However, this property is not general, and fly ash samples do not possess dehalogenation ability at all in many cases. Fly ash has a very variable composition, and the state of the fly ash matter therefore plays the decisive role. In the present paper, the function of important components responsible for the dehalogenation activity of MWI-FA is analysed and compared with the model fly ash. METHODS: With the aim of accounting for the dehalogenation activity of MWI-FA, the following studies of hexachlorobenzene (HCB) dechlorination were performed: The role of copper in dehalogenation experiments was evaluated for five types of metallic copper. The gasification of carbon in MWI-FA was studied in the 250-350 degrees C temperature range. Five different kinds of carbon were used, combined with conventional Cu(o) and activated nanosize copper powder. The dechlorination experiments were also carried out with Cu(II) compounds such as CuO, Cu(OH)2, CuCl2 and CuSO4. The results were discussed from the standpoint of thermodynamics of potential reactions. Based on these results, the model of fly ash was proposed, containing silica gel, metallic copper and carbon. The dechlorination ability of MWI-FA and the model fly ash are compared under oxygen-deficient atmosphere. CONCLUSIONS: The results show that, under given experimental conditions, copper acts in the dechlorination as a stoichiometric agent rather than as a catalyst. The increased surface activity of copper enhances its dechlorination activity. It was found further that the presence of copper leads to a decrease in the temperature of carbon gasification. The cyclic valence change from Cu(o) to Cu+ or Cu2+ is a prerequisite for the dehalogenation to take place. RECOMMENDATION AND OUTLOOK: Thermodynamic analysis of the dechlorination effect, as well as the comparison of dechlorination pathways on MWI-FA and model fly ash, can provide a deeper understanding of the studied reaction.     

Household Demand for Waste Recycling Services

Municipalities everywhere are coping with increasing amounts of solid waste and need urgently to formulate efficient and sustainable solutions to the problem. This study examines the use of economic incentives in municipal waste management. Specifically, we address the issue of recycling, if and when this waste management option is—on social welfare grounds—a preferred solution.A number of studies have recently assessed the monetary value of the externalities of alternative solid waste management options. In the present context, these subsidies could be interpreted as the implicit value of the benefits from reducing environmental externalities associated with landfilling as perceived by local government authorities. We surmise that the difference between mean households willingness to pay (WTP) for recycling services, via the purchase of a subsidized waste disposal facility, and the above (proxy) value of externalities reflects the difference between private and public perception regarding the negative externality associated with landfilling. We believe that this information is useful in determining the level of subsidization needed (if at all) to sustain any recycling program.The study is unique in the sense that its conclusions are based on revealed household behavior when faced with increased disposal costs, as well as information on WTP responses in hypothetical but related (and, therefore, familiar) scenarios. The article also explores the influence of the subsidization schemes on recycling rates. It was found that with low levels of effort needed to participate in a curbside recycling program, households participation rates are mainly influenced by economic variables and age, and households are willing to pay a higher price for the recycling scheme. When the required effort level is relatively high, however, households would pay a lower price, and the rate is influenced mainly by their environmental commitment and by economic considerations. We found that in both cases a subsidy would be required in order to achieve an efficient level of recycling. The median price that households are willing to pay for recycling devices is found to be about NIS 370 (New Israeli Shekel, approximately $90).     

A critical review of economic valuation studies of externalities from incineration and landfilling.

The primary objective of this study was to assist waste management researchers, decision-makers and waste managers at national, regional and local levels, in their decision-making processes, with most recent valuations on the environmental and social costs of externalities associated with various pollutants and disamenities related to landfilling and incineration of municipal solid waste. The aim was achieved by mapping, gathering, analysing, comparing and synthesizing various valuation estimates, based on a thorough review of existing literature. This study provides the first comprehensive review and analysis focused on primary and secondary valuation studies, conducted since 1990. The second objective was to assess the appropriateness and reliability of the valuation methods and techniques that were performed in the reviewed studies. The results of the review are summarized in tables, organized by topics and units of measure and in addition a classified list that describes the profile of the reviewed studies is provided. The results are then analysed and compared, and recommended ranges of the values are presented. The study reveals inconsistency in part of the estimates across the reviewed studies and provides reasonable explanations for the variations. Given the nature of uncertainty, and the difficulties associated with transferring values among different places and cases, these values should be considered mostly as an indication for the order of magnitude of the externalities. Nevertheless, these essential estimates of the external costs can beneficially be used with proper adjustment for each individual case to address important policy questions regarding landfilling and incineration of waste.     

Economic cost of mineral supply disruptions: Effects on a small, open economy

The potential impact of short-run disruptions in the minerals market on Israel's small, developed open economy is examined, showing that Israel is potentially capable of a smoother adjustment to external market disturbances. First, the analysis evaluates critical situations within the framework of a normative ‘general equilibrium model’, tracing the impacts of short-run developments in the resources market, and, second, it focuses on specific minerals within a partial equilibrium framework, using economic supply - demand relationships to assess economic damages. The potential damage estimates indicate that significant research and development outlays in the areas of material and process substitution and the capability for a quick build-up of contingent inventories would be justified to prevent the damages which supply disruption might inflict on the economy.