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Castel Guelfo di Bologna, Italy

Salomoni C.,Biotec Sys Srl | Caputo A.,Biotec Sys Srl
Journal of Hazardous Materials

In the present study, the chemical features of municipal wastewater sludges treated in two-phase separate digesters (one for acetogenesis and the other one for methanogenesis), were characterized by using chemical analysis, stable carbon isotope ratios (δ13C), HS-SPME-GC-MS, TG-DTA analysis and DRIFT spectroscopy. The results obtained showed that sludges from acetogenesis and methanogenesis differed from each other, as well as from influent raw sludges. Both processes exhibited a diverse chemical pattern in term of VFA and VOC. Additional variations were observed for δ13C values that changed from acetogenesis to methanogenesis, as a consequence of fermentation processes that led to a greater fractionation of 12C with respect to the 13C isotope. Similarly, the thermal profiles of acetogenesis and methanogenesis sludges greatly differed in terms of heat combustion produced. These changes were also supported by higher lipid content (probably fatty acids) in acetogenesis than in methanogenesis, as also shown by DRIFT spectroscopy. © 2009 Elsevier B.V. All rights reserved. Source

Bonoli M.,Biotec Sys Srl | Salomoni C.,Biotec Sys Srl | Caputo A.,Biotec Sys Srl | Francioso O.,University of Bologna | Palenzona D.,Biotec Sys Srl
Chemical Engineering Transactions

Industrial by-products and wastes can be very challenging substrates for anaerobic digestion, since their composition in terms of nutrient content can be strongly unbalanced. Tannery by-products, for instance, are biomasses of animal origin with high nitrogen content since their composition is dominated by proteins, peptides and amino acids. The use of this biomass as main substrate to feed anaerobic digestion is limited because of the high concentrations of ammonia formed during fermentation. Ammonia is originated from the biological degradation of proteinaceous materials in anaerobic environment. Free ammonia permeation into bacterial cells can cause intracellular pH change, inhibition of specific enzymatic activities and increased energy requirement for cell maintenance. Therefore, high ammonia amount cause severe inhibition or failures of anaerobic digestion, with important consequences for both process stability and productivity. The aim of this study was the development of a multiphase anaerobic digestion process for tannery byproducts, characterized by a C/N ratio below 5, in order to convert them into biogas. The process needed an acclimation phase of anaerobic microorganisms due to high concentrations of ammonia (NH4 +/NH3), above 9,000 mg/L, and the low C/N ratio. Implication for process stability, microbial activity and for the achievement of the target performances are discussed. Copyright © 2014,AIDIC Servizi S.r.l. Source

Salomoni C.,Biotec Sys Srl | Caputo A.,Biotec Sys Srl | Bonoli M.,Biotec Sys Srl
Bioresource Technology

Cost-effective technologies are needed to reach the international greenhouse gas (GHG) reduction targets in many fields, including waste and biomass treatment. This work reports the effects of CO2 capture from a combustion flue gas and its use in a newly-patented, two-phase anaerobic digestion (TPAD) process, to improve energy recovery and to reduce CO2 emissions. A TPAD process, fed with urban wastewater sludge, was successfully established and maintained for several months at pilot scale. The TPAD process with injection of CO2 exhibits efficient biomass degradation (58% VSS reduction), increased VFA production during the acidogenic phase (leading to VFA concentration of 8.4g/L) and high biomethane production (0.350Sm3/kgSSV; 0.363Sm3/m3 react·d). Moreover, CO2 intake in the acid phase has a positive impact on the overall GHG balance associated to biomethane production, and suggests an improved solution for both emission reduction and biomass conversion into biomethane. © 2011 Elsevier Ltd. Source

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