812 research outputs found
Fanghi di depurazione: ieri, oggi, domani - l’evoluzione di un percorso
No full textfanghi di depurazione concentrano in meno del 2% del volume delle acque di rifiuto, oltre la metà della sostanza organica in esse contenuta. Poiché contengono anche contaminanti chimici e biologici che possono rappresentare rischi per la salute umana e l’ambiente, sono classificati come rifiuto speciale. Tuttavia, sono anche fonte potenziale di risorse che, direttamente o indirettamente, tramite processi chimico-fisici o
biologici, possono portare a recuperi interessanti di varie materie. La produzione annua globale di fanghi di depurazione nel mondo è stimata in 45 milioni di tonnellate di materia secca. In futuro si possono prevedere quantità maggiori a causa dell’espansione delle reti fognarie e/o del potenziamento degli impianti, parzialmente compensati da nuovi processi innovativi che portano a una minore produzione di fanghi (Ferrentino et al.,
2023). La stima della produzione annua nella UE a 27 è di 8,1 milioni di tonnellate di fanghi umidi (dati Eurostat del 2019 riportati da Egle et al., 2023), corrispondenti a circa 2 milioni di tonnellate di materia secca. La produzione di fanghi di depurazione di acque reflue urbane in Italia è di circa 3 milioni di tonnellate (dato 2021; ISPRA, 2023), di cui circa 48 000 tonnellate sono conferite all’estero.Sewage sludge concentrates more than half of the organic substance in less than 2% of the volume of wastewater. Since sludge also contains chemical and biological contaminants that can pose risks to human health and the environment, it is classified as special waste. However, it is also a potential source of resources that, directly or indirectly, through chemical-physical or biological processes, can lead to interesting recoveries
of various materials. The annual global production of sewage sludge in the world is estimated at 45 million tons of dry matter. In the future, greater quantities can be expected due to the expansion of sewage networks and/or the upgrading of plants, partially compensated by new innovative processes that lead to a lower production of sludge (Ferrentino et al., 2023). The annual production estimate in the EU-27 is 8.1 million tonnes of wet sludge (Eurostat data from 2019 reported by Egle et al., 2023), corresponding to approximately 2 million tonnes of dry matter. The production of sewage sludge from urban wastewater in Italy is approximately 3 million tonnes (2021 data; ISPRA, 2023), of which approximately 48,000 tonnes are sent abroad. Today, several new technological and management options are opening up for the treatment of sludge, which, in addition to diversifying its destinations, promote the recovery of material and energy according to the principles of the circular economy
Modelling NOB activity under different dissolved oxygen, ammonia and nitrite concentrations
No full textBatch tests were conducted on sludge samples drawn from a nitrifying/denitrifying SBR fed on a synthetic wastewater to search for causes of the observed nitrification unbalancing, focusing on the effects of dissolved oxygen and ammoniacal and nitrous nitrogen concentrations on nitrite oxidising bacteria. Ammonium and nitrite oxidation rates were assessed by pH/DO-stat titration, i.e. by measuring the rate of addition of an alkaline solution and of an oxygen-reach solution required to maintain constant, at a selected set-point level, both pH and dissolved oxygen (DO) concentration of the sludge sample. According to experimental results, nitrite oxidising bacteria (NOB) were penalised under DO limitation (DO half saturation constant for ammonia and nitrite oxidation were 0.1 and 0.4 mg l-1, respectively). Several inhibition functions were found to describe the effect of increasing nitrite and ammonia concentrations on NOB allowing to assess the EC50 values for both chemical species
World Climate Research Program Special Workshop on Climatic Effects of ozone depletion in the southern hemisphere: assessing the evidence and identifying gaps in the current knowledge
No full textA World Climate Research Programme (WCRP) Special Workshop titled the “Climatic effects of ozone depletion in the Southern Hemisphere: Assessing the evidence and identifying gaps in the current knowledge” focused on the current understanding of Southern Hemisphere (SH) ozone depletion, in particular high-latitude ozone depletion, with regards to its impacts on hemispheric climate and its role relative to greenhouse gas (GHG)–induced climate changes. The 2010 United Nations Environment Programme (UNEP)/World Meteorological Organization (WMO) Scientific Assessment of Ozone Depletion, and research published since, provided the starting point for discussion. The workshop was supported by WCRP, the National Science Foundation (NSF; United States), the National Aeronautics and Space Administration (NASA; United States), Agencia Nacional de Promoción Científica y Técnica (Argentina), and the Pontificia Universidad Católica Argentina (Argentina).Fil: Canziani, Pablo Osvaldo. Pontificia Universidad Católica Argentina ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Oneill, Alan. National Centre For Earth Observations; Reino UnidoFil: Schofield, R.. University of Melbourne; AustraliaFil: Raphael, M.. University of California at Los Angeles; Estados UnidosFil: Marshall,G. J.. British Antarctic Survey; Reino UnidoFil: Redaelli, G.. Universita degli Studi dell'Aquila; Itali
Energy efficient WWTPs: simulation and validation of a decision support system through modelling
No full textMathematical modelling has been tested as a decision support system to management of a biological WWTP, aimed at optimizing energetic efficiency. A conventional activated sludge plant has been studied and the ASM1 mathematical model has been implemented, calibrated and validated, by using West 2012, DHI software. Optimal operating strategies, under different operating conditions, such as variable influent loading, have been defined. Also, indicators concerning energy efficiency and effluent quality have been defined and quantified
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