BACKGROUND: Municipal solid waste is generally disposed of by incineration or landfilling. Higher combustion efficiencies or lower waste amounts to be dumped, respectively, can be obtained through recovery of the waste wet fraction, which could be valorized by means of anaerobic digestion processes with the production of a CH4‐rich biogas. However, such a fraction is typically poorly digestible. The aim of this work was to obtain a methanogenic consortium capable of effective biomethanization of the wet fraction collected from a municipal solid waste. RESULTS: An up‐flow recirculated column bioreactor (0.36 L) was initially filled with cattle manure and then, after a short batch working period, fed with the above mentioned target substrate according to a semicontinuous scheme. More than 90% of the overall COD fed during the whole 5‐months experiment was depleted. The methane production yield gradually increased throughout the process to 0.35 L g−1 of depleted COD. Molecular analysis of the microbial consortium indicated that the archaeal population, which consisted of two acetoclastic Methanosarcina sp. strains, persisted during the whole experiment, whereas several hydrolytic and acidogenic Firmicutes and Bacteroidetes were enriched throughout the process, concomitantly to the increase of the biomethanization potential of the consortium. CONCLUSIONS: An anaerobic consortium capable of efficiently converting the wet fraction of municipal solid waste into methane was obtained through a dedicated enrichment procedure in an up‐flow anaerobic recirculated reactor. This result was mainly ascribed to the acclimation and enrichment of bacterial species. Copyright © 2012 Society of Chemical Industry

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Packed microcosms, consisting of 0.6 L-flask filled with tire chips (TC, a non-cost-recyclable non-biodegradable material) or ceramic cubes, were employed in the wet batch mesophilic anaerobic codigestion of a mechanically sorted organic fraction of a municipal solid waste with cattle manure. Two different waste mixtures were digested within four successive batch experiments, performed by collecting the digested waste and by refilling each microcosm with the same experimental mixture. Methane production yields related to the first experiment were comparable to those of non-packed identically developed microcosms, while they significantly grew during all the following experiences. No CH4-production lag-phase was observed since the second batch experiment. Similar results were obtained for both packing materials: however, the highest methane yields were achieved within bioreactors packed with TC in the presence of a mixture in which the volatile suspended solids (VSS) provided by the municipal waste represented the 55% of the total ones. Under such condition, a methane yield corresponding to the biochemical methane potential (BMP) calculated through a 6-month experiment with non-packed microcosms (176 ml/gVS) was attained in about 1/4 of the time. Importantly, the BMP can significantly grow up as a consequence of the approach described in this study.

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This work was aimed at studying the possibility of biodegrading 4-nonylphenol and low ethoxylated nonylphenol mixtures, which are particularly recalcitrant to microbial degradation, by employing a biofilm reactor packed with a ceramic support (Vukopor® S10). A selected microbial consortium (Consortium A) was used to colonize the support. 4-Nonylphenol and ethoxylated nonylphenol degradation and mineralization capabilities were studied both in batch and continuous mode. The results showed that Vukopor® S10 was able to be colonized by an active biofilm for the degradation of the target pollutants with the reactor operating both in batch and continuous mode. On the other hand, pollutant adsorption on the support was negligible. FISH showed equal proportion of Alphaproteobacteria and Gammaproteobacteria in the Igepal CO-520 degrading reactor. A shift towards high proportion of Gammaproteobacteria was observed by supplying Igepal CO-210. PCR-density gradient gel electrophoresis (DGGE) analyses also evidenced that the biofilm evolved with time by changing the mixture applied and that Proteobacteria were the most represented phylum in the biofilm. Taken together, the data obtained provide a strong indication that the biofilm reactor packed with Vukopor® S10 and inoculated with Consortium A could potentially be used to develop a technology for the decontamination of 4-nonylphenol and low ethoxylated nonylphenol polluted effluents.