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.     

Reconsidering the Dynamic Interaction of Renewable Resources and Population Growth: A Focus on Long-Run Sustainability

Within the framework of a general equilibrium model we study the long-run dynamics of resources and population if the growth rate of resources and population and the share of labor devoted to production are adversely affected by resource scarcity. Our results show that sustainability, i.e. a positive value of resources and population in the long run, essentially depends on the level of per capita resources at which these feedback mechanisms become active. A detailed bifurcation analysis evidences the richness of possible long-run dynamics.     

Governance of seed and food security through participatory plant breeding: Empirical evidence and gender analysis from Syria

This paper presents the findings of a study on the governance of seed conducted in the framework of a participatory plant breeding (PPB) programme, based on a multi‐year inquiry with a panel of ten Syrian households. The study assessed the interactions between governance regimes regulating the rights to access and control genetic resources at international and national level, compared to the actual ability of the respondent women farmers to access and control the seed of varieties they co‐developed with the PPB programme. The paper argues that gender equal access to seed can “optimally” contribute to enhancing household food security in small scale farming. The paper also argues that to support a gender‐equal access to seed in the respondent households legislation needs to explicitly protect the rights of women farmers to access and share the benefits of genetic material and draw from empirical evidence of the actual access to and control of seed at ground level.     

Bisphenol A endocrine disruptor complete degradation using TiO2 photocatalysis with ozone

Bisphenol A is an endocrine disruptor. Complete mineralization of bisphenol A is therefore a primary environmental issue. Here, the combination of ozonation and photocatalysis by TiO₂ is proposed for the degradation and final mineralization of bisphenol A. TiO₂ films deposited onto two sides of an Al lamina show good stability and high surface roughness. We used a specific experimental setup employing two facing ultraviolet lamps and TiO₂ layers, together with an ozone flux. High-performance liquid chromatography–mass spectrometry determinations on bisphenol A solutions sampled at different reaction times and Fourier Transform Infrared analyses of the oxide at the end of the reaction were performed to study the reaction intermediates and the overall degradation mechanism. Our results show that pollutant mineralization achieved with the combined method is far higher, of 55% in the case of 0.3 mM bisphenol A, than those obtained by individual treatments such as photolysis (<3%), ozonation (6%), photocatalysis (6%), and by other combined processes: photolytic ozonation (13%) and catalytic ozonation (15%). This finding is explained by the occurrence of highly synergistic effects.