The microbial community structure of pig manure slurry (PMS) was determined with comparative analysis of 202 bacterial, 44 archaeal and 33 eukaryotic small subunit (SSU) rDNA partial sequences. Based on a criterion of 97% of sequence similarity, the phylogenetic analyses revealed a total of 108, eight and five phylotypes for the Bacteria, Archaea and Eukarya lineages, respectively. Only 36% of the bacterial phylotypes were closely related (>or=97% similarity) to any previously known sequence in databases. The bacterial groups most often represented in terms of phylotype and clone abundance were the Eubacterium (22% of total sequences), the Clostridium (15% of sequences), the Bacillus-Lactobacillus-Streptococcus subdivision (20% of sequences), theMycoplasma and relatives (10% of sequences) and the Flexibacter-Cytophaga-Bacteroides (20% of sequences). The global microbial community structure and phylotype diversity show a close relationship to the pig gastrointestinal tract ecosystem whereas phylotypes from the Acholeplasma-Anaeroplasma and the Clostridium purinolyticum groups appear to be better represented in manure. Archaeal diversity was dominated by three phylotypes clustering with a group of uncultured microorganisms of unknown activity and only distantly related to the Thermoplasmales and relatives. Other Archaea were methanogenic H2/CO2 utilisers. No known acetoclastic Archaea methanogen was found. Eukaryotic diversity was represented by a pluricellular nematode, two Alveolata, a Blastocystis and an Entamoebidae. Manure slurry physico-chemical characteristics were analysed. Possible inhibitory effects of acetate, sulphide and ammonia concentrations on the microbial anaerobic ecosystem are discussed.

Tequila industries in general produce great volumes of effluents with high pollutant loads, which are discharged (untreated or partially treated) into natural receivers, thus causing severe environmental problems. In this contribution, we propose an integrated system as a first step to comply with the Mexican ecological norms and stabilize the anaerobic treatment of Tequila vinasses with main design criteria: simple and easy operation, reduce operating time and associated costs (maintenance), integrated and compact design, minimal cost of set-up, start-up, monitoring and control. This system is composed of a fully instrumented and automated lab-scale CSTR-type digester, on-line measuring devices of key variables (pH, temperature, flow rates, etc.), which are used along with off-line readings of chemical oxygen demand (COD), biogas composition, alkalinity and volatile fatty acids to guarantee the operational stability of the anaerobic digestion process. The system performance was evaluated for 200 days and the experimental results show that even under the influence of load disturbances, it is possible to reduce the COD concentration to 85% in the start-up phase and up to 95% during the normal operation phase while producing a biogas with a methane composition greater than 65%. It is also shown that in order to maintain an efficient treatment, the buffering capacity (given by the alkalinity ratio, alpha = intermediate alkalinity/total alkalinity) must be closely monitored.

No abstract

No abstract

No abstract

No abstract

In the present study, the capacity of the cyanobacterium Leptolyngbya sp. CChF1 to remove CO from real and synthetic biogas was evaluated. The identification of the cyanobacterium, isolated from the lake Chapala, was carried out by means of morphological and molecular analyses, while its potential for CO removal from biogas streams was evaluated by kinetic experiments and optimized by a central composite design coupled to a response surface methodology. Results demonstrated that Leptolyngbya sp. CChF1 is able to remove CO and grow indistinctly in real or synthetic biogas streams, showing tolerance to high concentrations of CO and CH, 25 and 75%, respectively. The characterization of the biomass composition at the end of the kinetic assays revealed that the main accumulated by-products under both biogas streams were lipids, followed by proteins and carbohydrates. Regarding the optimization experiments, light intensity and temperature were the studied variables, while synthetic biogas was the carbon source. Results showed that light intensity was significant for CO capture efficiency (p = 0.0290), while temperature was significant for biomass production (p = 0.0024). The predicted CO capture efficiency under optimal conditions (27.1 °C and 920 lx) was 93.48%. Overall, the results of the present study suggest that Leptolyngbya sp. CChF1 is a suitable candidate for biogas upgrading.

BACKGROUND Pilot‐scale studies focused on evaluating the robustness of biofilm‐based anaerobic digestion processes for further application at full‐scale are scarce. Therefore, the aim of this work was to evaluate the performance of a 445 L packed bed reactor (PBR) operated at different organic loading rates (OLRs between 4 and 12.5 g COD L‐1 d‐1) for the treatment of tequila vinasses. The reactor performance was correlated with the microbial dynamics to elucidate the specific role of the microbial communities in the degradation pathways that govern the process. RESULTS The PBR was operated for 231 days under different OLRs showing a stable performance. The COD removal and methane yield were maintained throughout the reactor operation at 86–89% and 0.24–0.28 L CH4 g‐1 CODadded, respectively. Meanwhile, the highest volumetric methane production rate of 3.03 L CH4 d‐1 L‐1 was reached at the highest OLR, 12.5 g COD L‐1 d‐1. Regarding microbial dynamics, the Bacteria and Archaea populations were able to adapt to the OLR disturbances, favoring the interactions between syntrophic Bacteria and Methanosaeta at high OLRs. CONCLUSION This work contributes to the scarce information regarding anaerobic treatment of tequila vinasses at pilot‐scale and demonstrates that the PBR is a promising and robust configuration that allows treating higher OLRs than currently reported technologies. © 2017 Society of Chemical Industry