1,721,072 research outputs found
Two step process for volatile fatty acid production from brewery spent grain: Hydrolysis and direct acidogenic fermentation using anaerobic granular sludge
Full text linkBrewery spent grain (BSG) is an industrial waste stream with large potential for biorefining purposes. This work evaluated the production of volatile fatty acids (VFAs) by a two-step process using BSG as renewable feedstock by combining a single direct hydrolysis step (without removing the acid or potential inhibiting compounds) with an acidogenic fermentation step of the carbohydrate rich leachate. For the first step, a thermal diluted acid hydrolysis was carried (20 min at 121 °C), using eighteen different combinations in terms of total solid (TS) of BSG (4, 7 and 10 % w/w) and H2SO4 (0.0, 0.5, 1.0, 1.5, 2.0 and 3.0 % v/v). The 7.0 % TS of BSG and 1.5 % of H2SO4 combination was the most efficient in terms of total carbohydrate recovery (0.44 g of total carbohydrates per gram of TS). For the second step, an acidogenic batch fermentation of the hydrolysate was performed using anaerobic granular sludge at five different pH conditions (uncontrolled pH from an initial pH 7.0, and constant pH controlled at 4.5, 5.0, 6.0 and 8.0). The highest VFAs concentration was obtained at pH 6.0 and reached 16.89 (± 1.33) g COD/L, composed of mainly (99.5–99.8 %) acetate and butyrate
Enhancement of biogas production from lignocellulosic materials by NMMO and Organosolv pretreatments
No full textThis study investigated the effects of two different chemical pretreatments on the
methane yields of three lignocellulosic materials (LMs), namely hazelnut skin and cocoa shells,
generated during the industrial processing of the raw agricultural products, and rice straw,
which is one of the most abundant agricultural wastes worldwide. Initially, the three LMs were
separately pretreated with an organic solvent, called N-Methylmorpholine-N-oxide (NMMO), at
120°C for 3 h. Consequently, batch bio-methane production (BMP) tests were performed under
mesophilic (i.e. 37 ± 2°C) conditions for 40 days. In a similar experimental run, the effects of
organosolv pretreatment on the three LMs were investigated. 50% ethanol was used as organic
solvent and the pretreatment was carried out at 150 and 180°C for 30 min. Both NMMO and
organosolv pretreatments were particularly effective for rice straw, enhancing the
biodegradability of the LM and, consequently, increasing the biogas yields compared to those
of the untreated material
Hydrogen and lactic acid synthesis by the wild-type and a laboratory strain of the hyperthermophilic bacterium Thermotoga neapolitana DSMZ 4359T under capnophilic lactic fermentation conditions
No full textThermotoga neapolitana is a hyperthermophilic eubacterium that produces hydrogen by sugar fermentation. A lab strain of T. neapolitana DSMZ 4359T maintained in a CO2-enriched atmosphere showed a stable increase of lactic acid production under capnophilic lactic fermentation (CLF) conditions. The genotypic comparison between the putative mutant (TN-CMut) and the original strain DSMZ 4359T (WT4359) revealed 88.1 (±2.4)% DNA homology. RiboPrint® and MALDI-TOF mass analyses support a genetic differentiation beyond subspecies level. The phenotypic characterization indicated a high correlation between the two strains, except for the lactic acid production. Under identical operating conditions, the lab mutant produced significantly more lactic acid than the parent strain without impairing the hydrogen yield. The highest divergence between TN-CMut and WT4359 was observed for fermentation of glucose or lactose at 80 °C. Based on these results, we propose that the lab strain is a new subspecies of the genus Thermotoga that is named T. neapolitana subsp. capnolactica with regards to its improved feature to produce lactic acid under capnophilic conditions
A Review of Microalgal Biofilm Technologies: Definition, Applications, Settings and Analysis
No full textBiofilm-based algal cultivation has many advantages over the conventional suspended growth methods and has received increased attention as a potential platform for algal production, wastewater treatment (nutrient removal), and a potential pathway to supply feedstock for microalgae-based biorefinery attempts. However, the attached cultivation by definition and application is a result of a complex interaction between the biotic and abiotic components involved. Therefore, the entire understanding of the biofilm nature is still a research challenge due to the need for real-time analysis of the system. In this review, the state of the art of biofilm definition, its life cycle, the proposed designs of bioreactors, screening of carrier materials, and non-destructive techniques for the study of biofilm formation and performance are summarized. Perspectives for future research needs are also discussed to provide a primary reference for the further development of microalgal biofilm systems
Impacts of sulfur source and temperature on sulfur-driven denitrification by pure and mixed cultures of Thiobacillus
No full textLong-term performance evaluation of an anoxic sulfur oxidizing moving bed biofilm reactor under nitrate limited conditions
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Biological sulfate reduction in different reactor configurations for treatment of construction and demolition debris sand leachate
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