Rudolf Paul Wilhelm Jozef Struis

Review of fly ash inertisation treatments and recycling

Fly ash (FA) is a by-product of power, and incineration plants operated either on coal and biomass, or on municipal solid waste. FA can be divided into coal fly ash, obtained from power plant burning coal, flue gas desulphurisation FA, that is, the by-product generated by the air pollution control equipment in coal-fired power plants to reduce the release of SO2, biomass FA produced in the plants for thermal conversion of biomass and municipal solid waste incineration (MSWI) FA, that is, the finest residue obtained from the scrubber system in a MSWI plant. Because of the large amount produced in the world, fly ash is now considered the world’s fifth largest material resource. The composition of FA is very variable, depending on its origins; then, also pollutants can be very different. In this frame, it is fundamental to exploit the chemical or physical potentials of FA constituents, thus rendering them second-life functionality. This review paper is addressed to FA typology, composition, treatment, recycling, functional reuse and metal and organic pollutants abatement. Because of the general growing of environmental awareness and increasing energy and material demand, it is expected that increasing recycling rates will reduce the pressure on demand for primary raw materials, help to reuse valuable materials which would otherwise be wasted and reduce energy consumption and greenhouse gas emissions from extraction and processing.

Studying sulfur functional groups in Norway spruce year rings using S L-edge total electron yield spectroscopy.

Profiles of the major sulfur functional groups in mature Norway spruce wood tissue have been established for the first time. The big challenge was the development of a method suitable for sulfur speciation in samples with very low sulfur content (<100 ppm). This became possible by synchrotron X-ray absorption spectroscopy at the sulfur L-edge in total electron yield (TEY) detection mode with thin gold-coated wood slices. Functional groups were identified using sulfur compound spectra as fingerprints. Latewood of single year rings revealed metabolic plausible sulfur forms, particularly inorganic sulfide, organic disulfide, methylthiol, and highly oxidized sulfur. Form-specific profiles with Norway spruces from three different Swiss forest sites revealed high, but hitherto little-noticed, sulfur intensities attributable to natural heartwood formation and a common, but physiologically unexpected maximum around year ring 1986 with trees from the industrialized Swiss Plateau. It is hypothesized whether it may have resulted from the huge reduction in sulfur emissions after 1980 due to Swiss policy. Comparison with total S content profiles from optical emission spectroscopy underlined the more accurate and temporally better resolved TEY data with single wood year rings and it opened novel insights into the wood cell chemistry.

Fly Ash Pollutants, Treatment and Recycling

This chapter reviews fly ash typology, composition, treatment, deposition, recycling, functional re-use, and metals and organic pollutants abatement. Fly ash is a by-product of power and incineration plants operated either on coal and biomass, or municipal solid waste. The growing of environmental awareness and increasing energy and material demand will foster recycling. Recycling will help to reuse valuable materials which would otherwise be wasted, and reduce energy consumption and greenhouse gas emissions from extract ion and processing. Fly ash is world’s fifth largest material resource because of the large amount of ash produced in the world. Fly ash can be classified into several categories: coal fly ash obtained from power plant burning coal; flue gas desulphurisation fly ash, that is the byproduct generated by the air pollution control equipment in coal-fired power plants to prevent (reduce) the release of SO2; biomass fly ash produced in the thermal conversion of biomass; and municipal solid waste incineration (MSWI) fly ash, that is the finest residue obtained from the scrubber system in a municipal solid waste incineration plant.

Advanced Thermal Treatment Processes

Waste incineration is a technology which is more than 100 years old. The technology was first introduced at the end of the 19th century to reduce the volume and mass of MSW in order to save landfill space. In a time when smoking stacks were synonymous with progress, nobody cared about the emissions from incinerators into the air. Only when air pollution became a high priority issue in the early 1980s was it found that MSW incinerators were in fact contributing substantially to the overall emission of air pollutants, notably of HO, dioxins and various heavy metals. Once this drawback to MSW incineration was acknowledged, legislation intervened and forced the environmental technology industry to develop suitable air pollution control (APC) technology, which in turn required that operators of incinerators invest large sums to limit the emission of acid gases, particulates and toxic trace compounds. The era of environmental technology from 1980 to 2000 has in fact brought down the emissions from incineration to levels that have made MSWI a minor contributor to air pollution for all emission categories [48].