Experimental hydrogenotrophic specific activity (SHMA) measurements are a useful tool in characterizing the activity of anaerobic biological sludge. They are a cost-effective tool to monitor the operation of pilot and industrial scale reactors for biogas production and upgrading. The activities carried out in the present master thesis have focused on two objectives: the first one concerns the study of the effect of the variation of operating parameters (initial pressure, mixing and volume of sludge) on the measurement of SHMA, by means of two different experimental devices, together with the on-line measurement of dissolved gas concentrations through the adoption of a membrane mass spectrometer; the analysis involves the use of a high activity sludge from an ex-situ pilot upgrading reactor in CSTR configuration, operating under mesophilic conditions; the second concerns the development of a mathematical model for the simulation of the SHMA test, accompanied by the parametric identification of the KLa of the system and the Ks of the biomass; this involves the adoption of a method of linear fractional transformation (LFT), using as output vectors measured headspace pressure, dissolved hydrogen and methane. In particular, for the first objective we report the materials and methods used, in order to identify the domain of the operating parameters chosen, the set-up of the experimental tests of SHMA and the analysis of dissolved gases, the steps necessary to calculate the value of SHMA from the measurement of the pressure variation in the headspace (based on the kinetics for the conversion H2/CO2 to methane); the comparison between the values of SHMA measured by the two devices is accompanied by the mass balance of COD, carried out to verify the accuracy of the measurements. On the other hand, a good fit of the experimental data was demonstrated for the model (TIC index < 0,3); it was reiterated that the KLa is strongly dependent on the imposed mixing while an average value of Ks equal to 1,42 10−5 molH2/L was estimated, confirming the orders of magnitude reported in literature.
Le misure sperimentali di attività specifica idrogenotrofa (SHMA) rappresentano un utile strumento nel caratterizzare l’attività dei fanghi biologici anaerobici. Esse sono un metodo economico e rapido per monitorare il funzionamento di reattori su scala pilota e su scala industriale per la produzione e l’upgrading del biogas. Le attività svolte nel presente elaborato di tesi magistrale hanno riguardato due obiettivi: il primo attiene allo studio dell’effetto della variazione dei parametri operativi (pressione iniziale, miscelazione e volume di fango) sulla misura dell’SHMA, tramite due differenti apparati sperimentali, unitamente alla misura in linea delle concentrazioni dei gas disciolti attraverso l’adozione di uno spettrometro di massa a membrana; le analisi prevedono l’utilizzo di un fango ad alta attività proveniente da un reattore pilota di upgrading ex-situ in configurazione CSTR, operante in condizioni di mesofilia; il secondo riguarda l’elaborazione di un modello matematico per la simulazione della prova di SHMA, accompagnato dall’identificazione parametrica della KLa del sistema e della Ks della biomassa; ciò prevede l’adozione di un metodo di trasformazione lineare frazionaria (LFT), utilizzando come vettori di uscita misurata la pressione nello spazio di testa, l’idrogeno e il metano disciolti. In particolare per il primo obiettivo si riportano i materiali e i metodi utilizzati, al fine di indentificare il dominio dei parametri operativi scelti, il set-up delle prove sperimentali di SHMA e dell’analisi dei gas disciolti, i passaggi necessari al calcolo del valore di SHMAdalla misura della variazione di pressione nello spazio di testa (sulla base della cinetica per la conversione H2/CO2 in metano); il confronto tra i valori di SHMA misurati dai due apparati viene accompagnato dal bilancio di massa del COD, svolto per verificare l’accuratezza delle misure. Per il modello invece si è dimostrato un buon fit dei dati sperimentali (indice TIC < 0,3); è stato ribadito come la KLa sia molto dipendente dalla miscelazione imposta mentre si è stimato un valore medio di Ks pari a 1,42 10−5 molH2/L, confermando gli ordini di grandezza riportati in letteratura.
Misura dell'attività specifica idrogenotrofa : impatto dei parametri operativi e modellazione del processo
Schiattareggia, Luca
2020/2021
Abstract
Experimental hydrogenotrophic specific activity (SHMA) measurements are a useful tool in characterizing the activity of anaerobic biological sludge. They are a cost-effective tool to monitor the operation of pilot and industrial scale reactors for biogas production and upgrading. The activities carried out in the present master thesis have focused on two objectives: the first one concerns the study of the effect of the variation of operating parameters (initial pressure, mixing and volume of sludge) on the measurement of SHMA, by means of two different experimental devices, together with the on-line measurement of dissolved gas concentrations through the adoption of a membrane mass spectrometer; the analysis involves the use of a high activity sludge from an ex-situ pilot upgrading reactor in CSTR configuration, operating under mesophilic conditions; the second concerns the development of a mathematical model for the simulation of the SHMA test, accompanied by the parametric identification of the KLa of the system and the Ks of the biomass; this involves the adoption of a method of linear fractional transformation (LFT), using as output vectors measured headspace pressure, dissolved hydrogen and methane. In particular, for the first objective we report the materials and methods used, in order to identify the domain of the operating parameters chosen, the set-up of the experimental tests of SHMA and the analysis of dissolved gases, the steps necessary to calculate the value of SHMA from the measurement of the pressure variation in the headspace (based on the kinetics for the conversion H2/CO2 to methane); the comparison between the values of SHMA measured by the two devices is accompanied by the mass balance of COD, carried out to verify the accuracy of the measurements. On the other hand, a good fit of the experimental data was demonstrated for the model (TIC index < 0,3); it was reiterated that the KLa is strongly dependent on the imposed mixing while an average value of Ks equal to 1,42 10−5 molH2/L was estimated, confirming the orders of magnitude reported in literature.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/187119