Humberto Escalante

Enhancement of starting up anaerobic digestion of lignocellulosic substrate: fique's bagasse as an example.

In Colombia there are 20,000 ha of fique fields (Furcraea sp., family Agavaceae), that produce around 93,400 tons of fiques bagasse per year. These residuals are disposed into rivers and soil causing pollution. According to physicochemical characteristics, the lignocellulosic residues from fique crops (fiques bagasse) are appropriate carbon source to biogas production. Anaerobic digestion from fiques Bagasse (FB) requires a specialized microbial consortium capable of degrading its high lignocellulosic concentration. In this study, the capacities of seven microbial consortia for biomethane potential (BMP) from FB were evaluated. Inoculum of ruminal liquid achieved high hydrolytic activity (0.068 g COD/g VSS day), whereas pig waste sludge inoculum showed high methanogenic activity (0.146 g COD/g VSS day). Mixtures of these two inoculums (RL+PWS) showed the best yields for biomethane potential (0.3 m(3) CH4/Kg VS ad).

Influence of nutritional and physicochemical variables on PHB production from raw glycerol obtained from a Colombian biodiesel plant by a wild-type Bacillus megaterium strain

Biodegradable polymers are currently viable alternatives to traditional synthetic polymers. For instance, polyhydroxybutyrate (PHB) is intracellularly produced and accumulated by Bacillus species, among others. This study reports several wild-type Bacillus strains with the ability to accumulate PHB using raw glycerol from biodiesel production as the sole carbon source. Out of 15 strains from different sources, B. megaterium B2 was selected as the most promising strain for further statistical optimization of the medium composition. Plackett-Burman and central composite designs were used to establish key variables and optimal culture conditions for PHB production using both 250-mL shake flasks and a 7.5-L bioreactor. Temperature and concentrations of glycerol and Na2HPO4 are the experimental variables with the most significant influence on PHB production by B2. After 14 hours of fermentation in shake flasks with optimized medium, B2 produced 0.43 g/L of PHB with a 34% accumulation in the cells. In contrast, under the same conditions, a maximum PHB concentration of 1.20 g/L in the bioreactor was reached at 11 hours. These values correspond to a 48% and 314% increase in PHB production compared to the initial culture conditions. These results suggest the potential of B2 as a PHB producer using raw glycerol, which is an inexpensive, abundant and readily available carbon source.

Spatial decision support system to evaluate crop residue energy potential by anaerobic digestion.

Implementing anaerobic digestion (AD) in energy production from crop residues requires development of decision tools to assess its feasibility and sustainability. A spatial decision support system (SDSS) was constructed to assist decision makers to select appropriate feedstock according to biomethanation potential, identify the most suitable location for biogas facilities, determine optimum plant capacity and supply chain, and evaluate associated risks and costs. SDSS involves a spatially explicit analysis, fuzzy multi-criteria analysis, and statistical and optimization models. The tool was validated on seven crop residues located in Santander, Colombia. For example, fique bagasse generates about 0.21millionm(3)CH4year(-1) (0.329m(3)CH4kg(-1) volatile solids) with a minimum profitable plant of about 2000tonyear(-1) and an internal rate of return of 10.5%. SDSS can be applied to evaluate other biomass resources, availability periods, and co-digestion potential.

Low cost digester monitoring under realistic conditions: Rural use of biogas and digestate quality

The purpose of this work was to assess the behaviour of anaerobic digestion of cattle manure in a rural digester under realistic conditions, and estimate the quality and properties of the digestate. The data obtained during monitoring indicated that the digester operation was stable without risk of inhibition. It produced an average of 0.85Nm3biogas/d at 65.6% methane, providing an energy savings of 76%. In addition, the digestate contained high nutrient concentrations, which is an important feature of fertilizers. However, this method requires post-treatment due to the presence of pathogens.

Anaerobic digestion of cheese whey: Energetic and nutritional potential for the dairy sector in developing countries

Cheese whey (CW) is the main waste generated in the cheesemaking process and has high organic matter content and acidity. Therefore, CW disposal is a challenge for small to medium enterprises (SMEs) in the dairy industry that do not have any type of treatment plant. Anaerobic digestion (AD) is an attractive process for solving this problem. The aim of this research was to determine the biomethane and struvite precipitation potentials of CW from four dairy SMEs. First, changes in CW properties (organic matter and pH) were evaluated. Second, biomethane and struvite potentials were assessed using cattle slurry as inoculum. The organic matter in CW varied from 40 to 65gVS/kg, 65 to 140g COD/L, and 2 to 10g/L for VFAs depending on the sampling time and type of sample. The pH of the CW samples ranged from 3 to 6.5. In the anaerobic biodegradability analysis, methane yields reached 0.51 to 0.60L CH4/g VSadded, which represented electrical and caloric potentials of 54 and 108kWh/m3 for CW, respectively. Organic matter removal in all experiments was above 83%. Moreover, anaerobic digestates presented NH4+/PO43- molar ratios between 2.6 and 4.0, which are adequate for struvite precipitation with potential production of 8.5-10.4g struvite/L CW. Finally, the use of biogas as energetic supplement and struvite as soil fertilizer, represents economics saves of US

Fuzzy spatial decision tool to rank suitable sites for allocation of bioenergy plants based on crop residue

6.91/m3 CW and US

Efecto de la carga orgánica de la gallinaza de jaula en el potencial de biometanización

5.75/m3 CW in therms of electricity and fertilizer use, respectively. The energetic, agricultural and economic potentials, evidence that AD process is a feasible alternative for cheese whey treatment.