Issue 2 [July]( Papers presented at 2nd International Conference on Engineering for Waste Valorisation - WasteEng2008, 3-5 June 2008, Patras, Greece )Editorial Decision support systems in solid waste management: A case study at the national and local level in GreeceAbeliotis K., Karaiskou K., Togia A. and Lasaridi K. , Pages:117-126 DOI: https://doi.org/10.30955/gnj.000590Paper Topic: General Issue: Issue 2Get Full Paper AbstractDecision support systems (DSS) are used to aid at solid waste management, a tedious problem with many technical, economic and social constraints. The main DSS available are briefly presented and the development of a novel system, ReFlows, is described. The novelty of the developed DSS consists of the detailed analysis of the collection subsystem and in particular the source separation and collection programs for recyclables materials. ReFlows utilises mathematical equations for material and financial flows, organised in several subroutines, to simulate the various sub-systems of an integrated solid waste management system and may be applied to any geographical scale, from the local to the national. The model, currently developed in MATLAB, is applied on recycling scenarios based on the degree of expansion of the different source collection schemes currently operating in Greece. Results are presented at a national (Greece) and a local level (Municipality of Athens). The main outcome of the study is that full expansion of the existing schemes may not fulfil the recovery goals for packaging waste in Greece. Improved collection schemes are required, based on more pilot programs in order to investigate the optimum recycling strategy. Utilization of metallurgical solid by-products for the development of inorganic polymeric construction materialsGiannopoulou I., Dimas D., Maragkos I. and Panias D., Pages:127-136 DOI: https://doi.org/10.30955/gnj.000589Paper Topic: General Issue: Issue 2Get Full Paper AbstractThis paper deals with the geopolymerization of the red mud generated in the primary aluminium production and the slag generated in the ferronickel production, in order to develop inorganic polymeric materials with advanced mechanical and physical properties. In particular, the effect of the main synthesis parameters of the inorganic polymeric materials on their mechanical strength and water absorption was investigated. Moreover, the structure of the inorganic polymeric materials was studied according to X-ray Diffraction analysis, Fourier Transform Infra Red spectroscopy and Scanning Electronic Microscopy. The inorganic polymeric materials produced by the geopolymerization of the red mud developed compressive strength up to 21 MPa and presented water absorption lower than 3 %, while the geopolymerization of the ferronickel slag resulted in materials with compressive strength higher than 110 MPa and extremely low water absorption (< 1 %). According to these results, the developed materials may be viewed as alternatives in the industrial sectors of construction and building materials. Effect of additives on the compressive strenght of slag-based inorganic polymersZaharaki D. and Komnitsas K., Pages:137-146 DOI: https://doi.org/10.30955/gnj.000585Paper Topic: General Issue: Issue 2Get Full Paper AbstractThe present paper aims to assess the effect of various additives on the compressive strength of inorganic polymers (geopolymers) synthesised using low Ca electric arc ferronickel slag and alkali activating solutions. The main operating parameters include pre-curing (48 hours), temperature (40 to 80 oC), heating time (24 or 48 h) and aging period (7 days). Addition of kaolinite, pozzolan, fly ash, red mud or CaO in the initial mixture has a detrimental effect on the final compressive strength. Addition of pulverised silica sand improves strength slightly, whereas addition of commercial glass results in strength values exceeding 60 MPa. XRD analysis was carried out to identify new formed phases and the degree of amorphicity, while SEM and element mapping analysis were used to identify the morphology of the final products as well as to elucidate to a certain degree the mechanisms involved in inorganic polymer synthesis. Valorisation of fly ashes by geopolymerisationProvis J.L., Duxson P., Harrex R.M., Yong C-Z. and van Deventer J.S.J., Pages:147-154 DOI: https://doi.org/10.30955/gnj.000588Paper Topic: General Issue: Issue 2Get Full Paper AbstractCoal fly ashes and metallurgical slags are currently widely used as supplementary cementitious materials in production of Portland cement-based concretes. However, this application makes very poor use of the intrinsic reactivity of the glassy phases present in the waste materials, and can hardly therefore be considered ‘valorisation’ in the true sense of the word. Addition of these materials to Portland cements can also cause difficulties in early strength development, limiting their use to certain applications. Geopolymerisation, on the other hand, makes full use of the glassy ash and slag materials by using them as the key reactants in synthesis of aluminosilicate gel binders for waste-based concrete production. The activation of the glassy phases by alkaline solutions provides the opportunity to greatly reduce the Portland cement content of a concrete, but requires a sound understanding of the ash chemistry and its effects on workability, water demand and setting time if it is to be implemented successfully on a commercial scale. In this paper, various aspects of fly ash valorisation via geopolymerisation are discussed, including in particular the determination of ash reactivity by a recently-developed technique utilising dilatometric data. The correlations between ash reactivity as measured by dilatometry and geopolymer mechanical strength are discussed in detail, and comparisons with other measures of ash reactivity presented. Some commercial examples of geopolymer concrete in-place are also discussed to highlight these differences in real world usage. High Strength Geopolymers Produced from Coal Combustion Fly AshNugteren H.W., Butselaar-Orthlieb V.C.L and Izquierdo M., Pages:155-161 DOI: https://doi.org/10.30955/gnj.000593Paper Topic: General Issue: Issue 2Get Full Paper AbstractHigh strength geopolymers were produced from coal combustion fly ashes. These matrices reached compressive strength values over 100 MPa, much stronger and denser than obtained by using Portland Cement binders. Size fractions were obtained by size separation techniques and the relationship between strength and particle size was investigated. The differences in compressive strength measured in the geopolymers made from fine fractions, the original fly ash and a coarse fraction of the same ash, were not significantly higher than the variation found for a reference geopolymer material. Therefore, a direct size-strength relationship could not be proven. Moreover, the chemistry and the pH of the fractions also varied, and this might as well has played a role in the strength development. Estimation of future methane production from Hellenic landfillsTsatsarelis T. and Karagiannidis A., Pages:162-171 DOI: https://doi.org/10.30955/gnj.000591Paper Topic: General Issue: Issue 2Get Full Paper AbstractThe main objective of this research was to predict expected methane generation in Hellenic sanitary landfills, in order to evaluate its potential for energy production and to ensure health and safety in and around these sites on the long term. The study was performed for the period 2008 – 2028 with the use of a multi-phase model and included also a sensitivity analysis in order to determine the impact of certain waste parameters. In this context, two ‘extreme’ reference scenarios were formulated and assessed, one anticipating fulfilment of the EU landfill directive (which sets limits to the amount of biodegradable and packaging materials to be deposited in sanitary landfills) whereas a second (do-nothing scenario) assuming no such timely compliance. A method to characterize the influence of air distribution on the composting treatment: monitoring of the thermal fieldsHenon F., Tremier A., Debenest G., Quintard M. and Mertel J-L., Pages:172-180 DOI: https://doi.org/10.30955/gnj.000594Paper Topic: General Issue: Issue 2Get Full Paper AbstractIn a composting process the monitoring of heat flows is a useful tool in terms of phenomenological comprehension and diagnosis of the process. Indeed, the temperature fields are generic markers of the micro-biological phenomena governing a composting process. Moreover, as heat flows are largely influenced by the air flowing through the porous solid waste, the temperature fields also characterize the influence of the air flow distribution on the composting process. However, at the industrial scale, it may be difficult to measure precisely the temperature distribution. In this paper, an in situ experimental data acquisition method of these thermal fields is described. Obtained data were used to reconstruct the evolution of the temperature in the whole composting reactor along the industrial composting process, in order to understand the influence of the air flow distribution. On the basis of these results, a model for the description of the thermal behaviour and the optimization of the aeration system was proposed. Bioremediation of crude oil-bearing soil: Evaluation of rhamnolipid addition as for the toxicity and crude oil biodegradation efficiency Millioli V.S., Servulo E.F.C., Sobral L.G.S. and de Carvaiho D.D., Pages:181-188 DOI: https://doi.org/10.30955/gnj.000592Paper Topic: General Issue: Issue 2Get Full Paper AbstractThis work is aimed at evaluating the potentiality of adding a rhamnolipid biosurfactant in a petroleum-bearing soil. For this purpose, dehydrogenase activity and seed germination (Lactuca sativa) testes were performed before the biodegradation assays with different concentrations of rhamnolipid (1 to 15mg for 1g of soil). The addition of 1 and 15 mg g-1 of rhamnolipid was harmful to the soil environment. The biodegradation assays were carried out at room temperature during 45 days in bioreactors containing 450g of a polluted soil with different rhamnolipid concentrations varying from 1 to 15 mg g-1. The nutrients were corrected through the addition of NH4NO3 and KH2PO4, in a nutritional ratio of C:N:P=100:15:1. The humidity was adjusted to 50% of the liquid retention capacity. Besides these assays, a control test was conducted without adding rhamnolipid. TPH (Total petroleum hydrocarbon) removal and seed germination were evaluated at the end of these experiments. When 4 mg g-1 of rhamnolipid were used a TPH removal of about 60% was observed. The biosurfactant addition improved all treatments, except for the assays with addition of 1 and 15 mg g-1 in which a decrease of the bioremediations rates was observed in the toxicity tests. Treatment and valorisation of stormwater sedimentsPetavy F., Ruban V., Conil P., Viau J-Y. and Auriol J.C., Pages:189-195 DOI: https://doi.org/10.30955/gnj.000584Paper Topic: General Issue: Issue 2Get Full Paper AbstractThe objective of this research is to show how sediment micro-pollution, including heavy metals, hydrocarbons and PAHs, can be reduced by means of a physical treatment based on screening and attrition. The study was carried out on five stormwater sediments, the developed pilot unit allows to isolate pollutants in the fine particles, hence a possible reuse of the coarse, unpolluted fractions. Geotechnical tests carried out on the treated sediments show that most of these fractions are likely to be reused as road embankments, capping layers or pipe embankments. The remediation of stormwater sediments is indeed possible and the development of a mobile unit is actually under study. As sediment treatment is a wide problem, largely exceeding stormwater, ATTRISED process could be used for the remediation of other sediments such as river dredging sediments or sediments from sewer networks. Determination of the optimal conditions for the adsorption of cadmium ions and phenol on chestnut(Castanea sativa) shellVazquez G., Gonzalez-Alvarez J., Freire M.S., Calvo M., Antorrena G., Pages:196-204 DOI: https://doi.org/10.30955/gnj.000587Paper Topic: General Issue: Issue 2Get Full Paper AbstractAdsorption of cadmium ions and phenol from aqueous solutions on chestnut (Castanea sativa) shell was studied. An incomplete 33 factorial design was applied to investigate the influence of the initial cadmium ions (20-60-100 mg l-1) or phenol concentration (0.01-0.255- 0.5 g l-1), temperature (10-25-40ºC for cadmium and 10-35-60ºC for phenol) and pH (5.5-7.0- 8.5 for Cd2+ ions and 2.5-6.0-9.5 for phenol) on the amount of contaminant adsorbed and on the adsorption percentage. Statistical analysis of the results showed the significance of the individual factors and their interactions on both adsorption processes. The best conditions for high cadmium ions and phenol removal within the experimental ranges of the variables studied were the natural pH (around 5.5) and a temperature of 25ºC for cadmium ions and 60ºC for phenol. Under these conditions, adsorption equilibrium was modelled by the Freundlich isotherm for cadmium ions and by the Langmuir isotherm for phenol. Pages1 2 next › last »