1,720,988 research outputs found
Evaluation of Nitrogen Non-Point Sources in Po River Near Turin
No full textThe non-point hydraulic and nitrogen loads in the stretch of Po river upstream and downstream from the city of Turin have been investigated, on the basis of regular data concerning quality and flow rates in the river in different periods of a reference year. The collected data have been organized in terms of hydraulic and mass balances, taking into account input points, affluents and withdrawals, and the missing terms as concern non-point loads or transfer phenomena with surrounding banks and connected aquifers have been identified.From the nitrogen speciation it was possible to distinguish between different contributions to river load, and to estimate presence of agricultural loads, run-off phenomena from impervious urban areas, aquifer connections. All these information can be useful for a better assessment of the surrounding territory in order to improve river quality for different uses
Full scale tests of short-term municipal solid waste incineration bottom ash weathering before landfill disposal
No full textProblem statement: Natural weathering is the most economic method of treatment in order to reduce the release of heavy metals present in the residue. Approach: The aim of the study was to optimize the minimum weathering times that were useful to reduce the lead release to within the Italian limits for landfill disposal. The mechanism of short-term weathering of MSWI bottom ash had been studied and its effect on the leaching of lead had been evaluated. Two bottom ash heaps had been realized for the experimental assessment: In one case an open-air situation was used, in the other, a heap placed under shelter was not exposed to rain. Results: The weathering course was monitored through the results of a leaching test that was carried out at different ageing times (EN 12457-2:2002). The total carbonates were also measured, at the same time, on the fine fraction of the weathered bottom ash (<1 mm). A fast decrease in lead release was observed in the analysis of the leachates and, at the same time, a decrease in pH and calcium concentration. The pH and leachate lead concentration control mechanisms were investigated and individuated. It had been possible to observe that the lead concentration was fundamentally a function of the pH. The Calcite precipitation that occurred from calcium hydroxide carbonation was the main reason for the decrease above all during the first days of the process, when the maximum quantity of CO2 was fixed by air. The pH value was controlled by Portlandite dissolution only at the beginning, after the pH control seems to be due to aluminum hydroxides. Conclusion: The most significant changes in the bottom ash were found to occur in the first 60 days. It had been possible to verify the limited influence of washing phenomena while it was confirmed that carbonation was the most important process in short-term weathering and that it had an important rule on limiting lead release
Caratterizzazione del rilascio delle scorie in relazione alle diverse condizioni del processo di incenerimento di RSU
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Evoluzione della sostanza organica nel percolato di discariche per rifiuti industriali
No full textWe examine the results of the characterization made on two MSWI bottom ash release test carried out on sample representative of 6 months of plant operation. Beyond the mineralogical, chemical, and particle-size characterization, we investigate in detail the release of heavy metals, both by first level characterization with pH static-test and by II level compliance test. The release was estimated also on the single dimensional class fraction. The behaviour of two ashes is similar and the influence of different total metals quantity is sensible only at the extreme values of pH. The effect of the pH is much obvious for the amphoteric metals (Al, Pb, Zn) whereas the particle size is the only macroscopic factor that influence the release of Cu. The final pH of the leachate is function of the dimensional class considered and the leaching test. We even observe some change in the release with distilled water (test UNI 10802) between the humid ash, as taken just after quenching in water, and the ash let exposed to the air for a time in between some hours to weeks. For the lead there is a strong drop of the final concentration in the leachate. We interpret this effect with carbonation of the bottom as
Fanghi di trattamento di acque reflue industriali
No full textViene analizzato e risolto a livello industriale un caso in cui l'elevato carico inquinante degli effluenti comporta la produzione elevata di fanghi nei processi di trattament
Wool scouring effluent treatment sludge disposal in brick production
No full textThe characteristics of sludges coming from biological and/or chemical treatment of wool scouring wastewater seem to make their utilization as raw material in brick production avoiding the cost of usual landfill disposal. As their low calorific value is in the range of 1500-2500 kJ/kg the heat content can be recovered completely in the kiln.
The particle size distribution of the dirt was measured both in sludge and in raw wool and trials were carried out using blends of sludge and virgin clay in brick production.The satisfactory results justified a scale-up and the system has been in operation since 1984 in Italy as industrial assessment in a brick manufactoring company using sludge coming from a combing mill 70 km away.
The industrial tests showed a further energy saving in brick wiredrawing , by increasing the smoothness of the blend and induced the company to start the continual full-scale use of the sludge at the rate of about 15,000 tons/year
Evaluation of Po River water quality in Torino (Italy): Effects of diffuse and local point loads
No full textThe aim of this paper is to examine the Po River water quality in a small stretch in Piedmont (northern Italy). In this stretch a large pollution load, derived from the wastewater treatment plant of Torino area (more than 2 million inhabitants), is discharged and diluted in the water. In this study this load has been quantified and modeled in order to understand the sources, destinations and effects of the emitted pollutants. The objective was to determine the impact produced by the Torino Wastewater Treatment Plant on the quality of the water, based on various hydrological conditions and the possible intervention on the point and diffuse load
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