Federico Micolucci

Changes in microbial community during hydrogen and methane production in two-stage thermophilic anaerobic co-digestion process from biowaste.

In this paper, the microbial community in a two-phase thermophilic anaerobic co-digestion process was investigated for its role in hydrogen and methane production, treating waste activated sludge and treating the organic fraction of municipal solid waste. In the acidogenic phase, in which hydrogen is produced, Clostridium sp. clusters represented 76% of total Firmicutes. When feeding the acidogenic effluent into the methanogenic reactors, these acidic conditions negatively influenced methanogenic microorganisms: Methanosaeta sp., (Methanobacteriales, Methanomicrobiales, Methanococcales) decreased by 75%, 50%, 38% and 52%, respectively. At the same time, methanogenic digestion lowered the numbers of Clostridium sp. clusters due to both pH increasing and substrate reduction, and an increase in both Firmicutes genera (non Clostridium) and methanogenic microorganisms, especially Methanosaeta sp. (208%). This was in accordance with the observed decrease in acetic (98%) and butyric (100%) acid contents. To ensure the activity of the acetate-utilizing methanogens (AUM) and the acetogens, high ratios of H2-utilizing methanogens (HUM)/AUM (3.6) were required.

Mesophilic and thermophilic anaerobic digestion of the liquid fraction of pressed biowaste for high energy yields recovery

Deep separate collection of the organic fraction of municipal solid waste generates streams with relatively low content of inert material and high biodegradability. This material can be conveniently treated to recovery both energy and material by means of simplified technologies like screw-press and extruder: in this study, the liquid fraction generated from pressed biowaste from kerbside and door-to-door collection was anaerobically digested in both mesophilic and thermophilic conditions while for the solid fraction composting is suggested. Continuous operation results obtained both in mesophilic and thermophilic conditions indicated that the anaerobic digestion of pressed biowaste was viable at all operating conditions tested, with the greatest specific gas production of 0.92m(3)/kgVSfed at an organic loading rate of 4.7kgVS/m(3)d in thermophilic conditions. Based on calculations the authors found that the expected energy recovery is highly positive. The contents of heavy metals and pathogens of fed substrate and effluent digestates were analyzed, and results showed low levels (below End-of-Waste 2014 criteria limits) for both the parameters thus indicating the good quality of digestate and its possible use for agronomic purposes. Therefore, both energy and material were effectively recovered.

Thermophilic two-phase anaerobic digestion of source-sorted organic fraction of municipal solid waste for bio-hythane production: effect of recirculation sludge on process stability and microbiology over a long-term pilot-scale experience

A two-stage thermophilic anaerobic digestion process for the concurrent production of hydrogen and methane through the treatment of the source-sorted organic fraction of municipal solid waste was carried out over a long-term pilot scale experience. Two continuously stirred tank reactors were operated for about 1 year. The results showed that stable production of bio-hythane without inoculum treatment could be obtained. The pH of the dark fermentation reactor was maintained in the optimal range for hydrogen-producing bacteria activity through sludge recirculation from a methanogenic reactor. An average specific bio-hythane production of 0.65 m(3) per kg of volatile solids fed was achieved when the recirculation flow was controlled through an evaporation unit in order to avoid inhibition problems for both microbial communities. Microbial analysis indicated that dominant bacterial species in the dark fermentation reactor are related to the Lactobacillus family, while the population of the methanogenic reactor was mainly composed of Defluviitoga tunisiensis. The archaeal community of the methanogenic reactor shifted, moving from Methanothermobacter-like to Methanobacteriales and Methanosarcinales, the latter found also in the dark fermentation reactor when a considerable methane production was detected.

Anaerobic Codigestion of Algal Material with Two Different Co-Substrates, Biowaste and Sewage Sludge: Process Yields and Behaviour Comparison.

The problem of algae disposing, especially in coastal and lagoon areas where eutrophication occurs in all its gravity, makes necessary to seek appropriate methods for the treatment of this organic material. The anaerobic digestion for the treatment of this biomass is currently of considerable interest, due the low environmental impact and the energy recovery at the same time. After a pre-screening analysis, it is possible to say that algal biomass completely meets the requirements needed for anaerobic digestion process. In this paper are reported the feasibility results of the anaerobic codigestion treatment of algal biomass. Pilot-scale continuous stirred tank reactors with working volumes of 3 and 1 m3 were used, and full-scale digestion operational conditions were applied. Anaerobic digestion process with algae and organic fraction of municipal solid waste was inhibited by high concentration of hydrogen sulfide. This process was feasible if the algae content in the feeding mixture was equal to 10 % (in terms of solids) and with addition of iron powder; on the other hand the co-treatment of sewage sludge appeared very interesting, in fact the biogas production rate increased from 0.4 to 0.8 m3/m3reactord and methane content reached 71 %.

Ammonia Concentration and Ph Control in Pilot Scale Two-phase Anaerobic Digestion of Food Waste for Hydrogen Production: Focus on Start-up

Ammonia Concentration and pH Control in Pilot Scale TwoPhase Anaerobic Digestion of Food Waste for Hydrogen Production: Focus on Start-up Cristina Cavinato*, Marco Gottardo, Federico Micolucci, David Bolzonella, Paolo Pavan. a University Ca’ Foscari of Venice, Department of Environmental Sciences, Informatics and Statistics, via Torino, Mestre Venezia, Italy. University of Verona, Department of Biotechnology, Strada le Grazie 15, Verona, Italy. cavinato@unive.it.

Bioprocess Network for Solid Waste Management

The anaerobic digestion process is a well-known and still growing technology. It has been implemented in full scale in several waste and wastewater treatment plants.