Articles and publications of Project M.E.TA. results
1) Nitrite and nitrate as electron acceptors for biological sulphide oxidation
G.Munz, A.Mannucci, J. Arreola-Vargas, F. Alatriste-Mondragon, F.Giaccherini, G.Mori
Department of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, 50139 Florence, Italy (E-mail: alberto.mannucci@dicea.unifi.it)
Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San José 2055, 78216 San Luis Potosí, Mexico
Cer2co (Centro Ricerca Reflui Conciari), Consorzio Cuoiodepur, Via Arginale Ovest 56020 San Romano – San Miniato (PISA), Italy
Abstract
Authotrophic denitritation and denitrification with sulphide were investigated at bench scale. The results indicated that the process allows to achieve complete sulphide removal in a wide range of operating conditions (SRT and T). Tested sulphide loads were estimated form the H2S produced in an anaerobic digester treating vegetable tannery primary sludge; nitrogen loads originated from the nitrification of the supernatant. Nitrogen removal efficiencies higher than 80% were reached in all the tested conditions once steady state was reached. Nitrite and thiosulphate tend to accumulate especially in the presence of variable environmental conditions.
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2) Anaerobic digestion of vegetable tannery and municipal sludge
F.Giaccherini, A.Mannucci, G.Munz, G.Mori, F.Alatriste-Mondragon, C.Lubello
Department of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, 50139 Florence, Italy (E-mail: alberto.mannucci@dicea.unifi.it)
Cer2co (Centro Ricerca Reflui Conciari), Consorzio Cuoiodepur, Via Arginale Ovest 56020 San Romano – San Miniato (PISA), Italy
Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San José 2055, 78216 San Luis Potosí, Mexico
Abstract
The possibility of treating vegetable tannery industry primary sludge (VTPS) through anaerobic digestion was investigated. A preliminary test was carried out using municipal anaerobic sludge as inoculum and VTPS as substrate in a continuously fed CSTR (Continuous-flow Stirred-Tank Reactor) under mesophilic conditions but no methane production was observed. As a consequence, different microbial community was used as inoculum. The process efficiency in two reactors (R1 and R2) was compared with the aim of evaluating microbial community adaptation towards the inhibiting character of the matrix. R1 was fed with a mixture of an increasing amount of VTPS and conventional domestic primary sludge (CDPS) and R2 with CDPS only as control. Results showed that it is possible to co-digest VTPS:CDPS up to 30:70 before COD and VSS removals decrease and acetate starts to accumulate. A COD and a VSS removal efficiency of 48.7% and 53.2% were obtained with a CDPS/VTPS ratio of 30/70. Through batch test, a specific methane productivity (SMP) of 0.27 NL CH4 g-1 VSSfed was estimated for R1 with a CDPS/VTPS ratio of 30/70, three times higher than the SMP obtained in batch test with CDPS as single substrate (0.09 NL CH4 g-1 VSSfed).
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3) Stoichiometry of sulphide oxidation with nitrate as electron acceptor
F.Giaccherini, F. Spennati, A.Mannucci, F. Alatriste-Mondragon, G.Mori, G.Munz
Dept of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, 50139 Florence, Italy
IPICYT, Camino a la Presa San José 2055, 78216 San Luis Potosí, Mexico
Cer2co, Consorzio Cuoiodepur, Via Arginale Ovest 56020 San Miniato (PISA), Italy
Introduction
The removal of nitrogen by using sulphide as electron donor is a potentially interesting solution when sulphate and nitrogen are abundant in an effluent (such as for tannery industry), that can be advantageously treated through anaerobic digestionAMPLIARE. This process was already investigated with reference both to liquid (Lu et al., 2009) and gaseous streams (Kleerebezem and Mendez, 2002; Mora et al. 2014); however, when biogas is treated in a biotrickling filter (BTF) at high volumetric load, biomass accumulation may lead to the clogging of the bed (Mannucci et al., 2012). Within the Biosur Life+ project we developed a moving bed biofilm reactor for gaseous effluent treatment, with the aim of allowing biomass removal and solids retention time control; in this context, however, it is still important to quantify the kinetics and the stoichiometry of the processes involved. Most of previous work on the kinetics and stoichiometry of sulphur compounds oxidation, were carried out with thiosulphate as electron donor (inter alia Mora et al., 2014), while very few tests (Munz et al., 2009; Mora et al. 2014) have been carried out with sulphide due to the difficulty of using a strongly volatile and, at the same time inhibiting, substrate (ampliare in riferimento alla sorgente di solfuro, spegando il perchè delle scelte) . This work is aimed at investigating denitrification with sulphide, in the presence of typical S/N ratio that can derive from the anaerobic digestion of primary sludge of tannery wastewater and estimating those parameters that can affect the production of biomass in a BTF, that is mainly, the stoichiometric coefficients of sulphide oxidizing bacteria (SOB) growth and the decay kinetics.
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4) Investigation on anaerobic co-digestion of vegetable tannery sludge and fleshing in laboratory scale experiments.
F. Giaccherini, A. Ricotti, A. Mannucci, G. Mori, F. Alatriste-Mondragon, C. Lubello, G. Munz
Department of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, 50139 Florence, Italy (corresponding author: giulio@dicea.unifi.it)
Cer2co (Centro Ricerca Reflui Conciari), Consorzio Cuoiodepur, Via Arginale Ovest 56020 San Romano – San Miniato (PISA), Italy
Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San José 2055, 78216 San Luis Potosí, Mexico
Abstract
In this work, the efficiency and the technical feasibility of the anaerobic digestion of vegetable tannery industry primary sludge (VTPS) was investigated. Tests were conducted under mesophilic conditions in three laboratory scale (150 L) reactors. The investigation included two different solids retention time (15 and 25 d) and the co-digestion of VTPS plus fleshing. Results showed that an increase of SRT, from 15 to 25 days, not many increases the specific biogas production of 0.06 NL biogas g-1 VSS removed, but the addition of 1:4 (in mass) of fleshing in the feeding increases the VSS reduction of 10% at the end of the period.
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5) Nitrite and nitrate as electron acceptors for biological sulphide oxidation
G.Munz, A.Mannucci, J. Arreola-Vargas, F. Alatriste-Mondragon, F.Giaccherini, G.Mori
Department of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, 50139 Florence, Italy (E-mail: alberto.mannucci@dicea.unifi.it)
Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San José 2055, 78216 San Luis Potosí, Mexico
Cer2co (Centro Ricerca Reflui Conciari), Consorzio Cuoiodepur, Via Arginale Ovest 56020 San Romano – San Miniato (PISA), Italy
Abstract
Authotrophic denitrification with sulphide using nitrate (R1) and nitrite (R2) as electron acceptor were investigated at bench scale. Different SRT (5 and 20 d) have been tested in R1 while R2 was operated at SRT = 13 d. The results indicated that the process allows to achieve complete sulphide removal in all testes conditions. Tested sulphide loads were estimated form the H2S produced in a pilot scale anaerobic digester treating vegetable tannery primary sludge; nitrogen loads originated from the nitrification of the supernatant. Average nitrogen removal efficiencies higher than 80% were observed in all the tested conditions once steady state was reached. A maximum specific nitrate removal rate equal to 0.35 g N-NO3- g SSV-1 d-1 have been reached in R1. Due to sulphide limitation, an incomplete denitrification have been observed and nitrite and thiosulphate tend to accumulate especially in the presence of variable environmental conditions both in R1 and R2. Lower SRT caused higher NO2accumulated/NO3reduced ratios (0.22 and 0.24, with SRT of 5d and 20 d, respectively) using nitrate as electron acceptor in steady state condition. Temperature decrease caused sudden NO2accumulated/NO3reduced ratio increasing in R1 and NO2- removal decreasing in R2.
6) Digestione anaerobica dei fanghi conciari. I risultati del progetto M.E.TA (Matter and Energy from Tannery Sludges)
Marco Viviani m.viviani@depuratoreaquarno.it - Consorzio Aquarno S.p.A.,Santa Croce sull’Arno (PI) Alberto Mannucci, Francesca Giaccherini, Giulio Munz – Università di Firenze,Firenze Maurizia Seggiani – Università di Pisa,Pisa Valerio Talarico – Po.Te.Co. s.c.r.l, Castelfranco di Sotto (PI) Francesca Gambineri – Laboratori Archa s.r.l., Pisa Gualtiero Mori – Consorzio Cuoiodepur S.p.A, San Miniato (PI) Giancarlo Bernini – Consorzio SGS S.p.A., Santa Croce sull’Arno (PI) Daniela Carlotti – Consorzio Conciatori di Ponte a Egola Soc. Coop., San Miniato (PI)
Riassunto
L’efficienza del processo di digestione anaerobica applicato ai fanghi conciari è valutata attraverso test a scala banco e scala pilota. La peculiarità delle matrici selezionate ha richiesto l’applicazione di pretrattamenti mirati e l’utilizzo di inoculi acclimatati per il raggiungimento di rese significative. Test a scala banco hanno permesso di identificare la sequenza ottimale di pretrattamento e le condizioni operative in grado di massimizzare l’efficienza del processo di digestione in termini di metano prodotto. Sono stati inoltre condotti test in continuo di co-digestione di fango conciario e fango civile che hanno permesso di identificare le condizioni limite di trattamento delle matrici selezionate nel corso del progetto.
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