1,721,026 research outputs found
Potabilizzazione delle acque: il ruolo del carbone attivo nella rimozione dei metalli pesanti e di altri microinquinanti
No full textThe role of food/microorganism ratio in denitrification reactors: How it affects the sizing and operation of the denitrification process
No full textTwo calculation models of the Specific Denitrification Rate (SDNR) are analyzed to highlight the sensitivity of this parameter to the Food:Microorganisms ratio in the denitrification reactor (F:MDEN). One of these models is empirical while the second was elaborated on a deterministic basis. Both models reveal a linear dependence of SDNR20°C on F:MDEN and in a first approximation they are comparable only in a narrow range of concentration of dissolved oxygen (DO) in denitrification, specifically DO=0.25-0.35 mg L-1 . These values frequently occur in well designed and well operated sewage treatment plants. Outside this range, the role of F:MDEN must necessarily be examined in combination with DO because of the relevant influence of the latter on the efficiency of the denitrification process
Ion exchange equilibria of arsenic in the presence of high sulphate and nitrate concentration
No full textIl recupero e riutilizzo di alluminio da fanghi provenienti dal comparto di trattamento chimico fisico di acque da potabilizzare: vantaggi economici ed ambientali
No full textEffect of a Further Maturation Phase on the Chemical and Environmental Properties of a Bio-stabilised Waste from a Mechanical–Biological Treatment Plant
No full textThis work aimed at investigate the effects of a maturation treatment on the chemical and environmental properties of a bio-stabilised waste (BSW) produced from a Mechanical Biological Treatment (MBT) plant. Whilst several studies assessed the effects of maturation on compost properties, only a few works focused on BSW subjected to prolonged stabilisation processes. To this aim, the BSW produced from a MBT plant was subjected to a further pilot-scale prolonged curing, monitoring volatile solids and carbon content. Furthermore, a detailed characterization was performed on three BSW samples collected at different treatment duration, evaluating the biological stability, the total metal content, the metal speciation and their release in water. The obtained results confirmed that the adoption of a prolonged maturation process could improve the characteristics of the BSW produced in the MBT plant. After 28 days of treatment, the BSW presented a dynamic respiration index (DRI) value proper of a biologically unstable matrix. However, a higher stability degree was observed after at least 118 days (as shown by the DRI, the C/N ratio and the humification indices). The adopted treatment entailed also an improvement of the environmental behaviour of the material due to the decrease in the release of metal and organic carbon, as also shown by the reduction in the mobile fraction of metals observed in the metal speciation analysis. This study also showed that a preliminary assessment of the biological stability of a matrix could be already obtained analysing several parameter such as DOC, volatile solids and carbon content
Humic Substances Extracted from a Bio-stabilized Waste Applying Different Operating Conditions
No full textHumic substances are the major constituents of the organic matter of soils and sediments and were adopted in different industrial applications for their high content of functional groups. Recently, the research interest is focused on the possibility of extract these substances also from organic wastes, such as biowastes. However, an interesting option could be to extract humic substances from other organic stabilized wastes that differently from compost has no further use. Namely, in this study the possibility of extract Humic Acids (HA) from the bio-stabilized waste produced from a Mechanical Biological Treatment plant adopting different maturation durations was evaluated. Furthermore, the effect of the main operating conditions applied during the alkaline extraction of the humic acids was also investigated (i.e. material particle size, liquid-solid ratio, NaOH concentration and extraction time), analysing the elemental composition, the main functional groups content and the optical properties of the extracted HA. The operating conditions that showed to improve the extraction extent were the NaOH concentration and the extraction time. Furthermore, the HA obtained in these specific conditions showed higher functional groups content and aromaticity, in agreement with the characteristics of the commercial HA, allowing to consider these substances for various industrial applications.[GRAPHICS]
Criteri per il corretto recupero e riutilizzo dei rifiuti: il caso della formulazione di cementi di miscela
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