Waste Management & Research: The Journal for a Sustainable Circular Economy

Physical characteristics, chemical composition and leaching behaviour of a waste fly ash from a coal-fired power station are reported. Particle size distribution was studied by the following techniques: sedimentation in a liquid medium; sedimentation in an air flow; and Fraunhofer diffraction of a laser beam. Results obtained by the different methods are in good agreement. Mineralogical content and chemical composition were determined by X-ray diffraction, electronic microprobe and X-ray fluorescence. Acid leaching of the samples was investigated, using the following strong acids in sequence: HCl + HNO₃, H₂F ₂, HClO₄. Analysis of leachates by atomic absorption shows trace metals In, Tl, Ge, Cu, Ga, Pb, Ni, Co, Mn, Cd, Zn, Cr.

In this work fly ashes from a Spanish power plant are characterized according to the type of particles, size distribution and chemical composition by means of physical methods. Three particle size fractions are leached by acids and analysis of trace elements in the leaching liquor is carried out. The concentration of trace metals is somewhat higher in the particles of smallest size.

Cadmium containing stabilizers are used only in certain polyvinylchloride (PVC) products for special weather, light or temperature resistance. The total consumption of cadmium used as a chemical stabilizer in Sweden is expected to be about 1.5 tonnes/year in 1991-1992, while the amount in pigments is approximated to be 6 tonnes/year. It is determined that most of the cadmium that enters into the combustible fraction of municipal solid waste (MSW) comes from plastics and pigments in various products. Acrylonitrile Butadiene Styrene copolymers (ABS) products are the main source of plastics contained cadmium pigments. These products are usually consumer electronics such as television and telephone sets, computer, radios, etc. In practice, it is very difficult for a country like Sweden to act alone and implement regulations for cadmium due to international trade and heavy import/export of products. There is no doubt that the transition period to adopt other alternatives, as requested by the Swedish Cadmium Ordinance, takes time and a flow of cadmium from plastic wastes into landfills and incinerators is expected during the coming years. This is also due to the long lifetime of some plastic products which contain cadmium. Continuous and consistent monitoring of cadmium in landfills and incineration plants is required in order to be able to evaluate the effect of the Ordinance on cadmium.

In the present paper, an operations research study on the planning and design of an improved solid waste collection and transportation system in the city of izmir, Turkey, is discussed. This study is based on a mixed integer programming model, focusing on the optimization of "total solid waste collection and transportation costs" and considering various transfer site, disposal site, fleet size and transportation options. A shadow price analysis on the early solutions of this model suggested some new scenarios. All solutions obtained are discussed. This paper discusses a desk-based study, the results of which have not been verified in field implementation.

The concept of a diversion credit to encourage the use of products or services that have reusable by-products is introduced. A methodology is developed to assist municipal government authorities in determining an equitable level of compensation for business activities having by-product reuse, which results in reduced solid waste generation. The methodology is based on the quantities of solid waste diverted, such that the credit would be proportional to the costs that would have been incurred if by-product materials had been handled within the municipal waste management system. The methodology is applied to a hypothetical consumer products example.

Plastic items in some portions of municipal solid waste (MSW), particularly from households and restaurants, have long been viewed as a disposal problem and a symbol of a "throwaway society". There is no question that the amount of plastics in solid waste is growing. However, this observation alone should not cause an hysteria of public policies for the separate management of the plastics or any other portion of the waste. The amount of plastics, and the contribution of the items discarded, must be viewed holistically in setting a solid waste management policy. This paper questions the basis for some U.S. plastics waste policy proposals by reviewing recent U.S. data on the effect of plastics on waste reduction, and the fate of discarded plastics products. Some alternative future policy directions are also discussed.

A method for data handling and analysis of daily waste collection amount is presented which improves the understanding of the mechanism of waste generation in Japan. Waste amounts were normalized, and moving averages (MAs) were calculated by taking specific daily change caused by residents' behaviour into consideration. The MA curve shows seasonal variation very clearly, and it enables various discussions concerning waste generation. It is argued that the method of data analysis derived could be applied to any municipality regardless of collection frequency.