Biological desulfurization of biogas from a field-scale anaerobic digester in Peru was tested using air injection (microaeration) in separate duplicate vessels and chemical desulfurization using duplicate iron filters to compare hydrogen sulfide (H₂S) reduction, feasibility, and cost. Microaeration was tested after biogas retention times of 2 and 4 h after a single injection of ambient air at 2 L/min. The microaeration vessels contained digester sludge to seed sulfur-oxidizing bacteria and facilitate H₂S removal. The average H₂S removal efficiency using iron filters was 32.91%, with a maximum of 70.21%. The average H₂S removal efficiency by iron filters was significantly lower than microaeration after 2 and 4 h retention times (91.5% and 99.8%, respectively). The longer retention time (4 h) resulted in a higher average removal efficiency (99.8%) compared to 2 h (91.5%). The sulfur concentration in the microaeration treatment vessel was 493% higher after 50 days of treatments, indicating that the bacterial community present in the liquid phase of the vessels effectively sequestered the sulfur compounds from the biogas. The H₂S removal cost for microaeration (2 h: $29/m³ H₂S removed; and 4 h: $27/m³ H₂S removed) was an order of magnitude lower than for the iron filter ($382/m³ H₂S removed). In the small-scale anaerobic digestion system in Peru, microaeration was more efficient and cost effective for desulfurizing the biogas than the use of iron filters.

Evaluación de la calidad de biol de segunda generación de estiércol de ovino producido a través de biodigestores

Propuesta de parámetros de diseño de un reactor UASB para el tratamiento de aguas residuales porcinas

Los efluentes del beneficio húmedo del café, comúnmente conocidos como aguas mieles, son generalmente desechados al ambiente sin tratamiento alguno y presentan una alta carga orgánica. Se evaluó la producción de gas metano a través del proceso de digestión anaerobia utilizando como inóculo estiércol fresco de vacuno. Para esto se llevó a cabo el ensayo del Potencial Bioquímico del Metano (PBM) utilizando un equipo manométrico de monitoreo continuo. Se evaluaron dos proporciones sustrato/ inóculo, obteniéndose como resultado un PBM de 481,2 ml CH₄/g SV sustrato (329,0 ml CH₄/g DQO sustrato) para la relación igual a 0,25 g SV sustrato/ g SV inóculo y un PBM de 377,0 ml CH₄/g SV sustrato (257,7 ml CH4/g DQO sustrato) para la relación igual a 0,5. Con este estudio a nivel laboratorio se demostró que, las aguas mieles son un sustrato capaz de degradarse de manera anaerobia para la posterior producción de biogás.

The purpose of this research was to evaluate the capability of lactic acid bacteria (LAB) to remove pathogens present in domestic wastewater, generated in the eco-touristic circuit Lomas de Lucumo (Lima, Peru). The pH decrease was used as an indicator of the elimination of fecal coliform bacteria in the treated water. Experiments included 36 treatments, which consisted of different mixtures of sugar molasses and a lactic acid bacteria inoculum (B-Lac) in proportions of 0, 1, 3, 5, 7 and 10% (v/v) and wastewater in a fixed proportion of 200 ml, under a completely randomized design (CRD) with factorial arrangement 6x6. The pH values on the third day were evaluated using an Analysis of Variance (ANOVA) followed by Tukey´s range test for mean differences (p < 0.05). The different treatments were analyzed in a first stage for 9 days, after which the best three were selected for a second evaluation: T16 (3% molasses and 5% B-Lac), T22 (5% molasses and 5% B-Lac) and T33 (10% molasses and 3% B-Lac); results show that the interaction effect between the two variables is significant. Finally, treatment T16 was selected as the most efficient, reaching a pH of 4.08 in a short time (3 days) that assured the complete removal of fecal coliform bacteria (9.65x10⁵ MPN/100 ml) in the wastewater.

Influencia de la fermentación láctica (abono bokashi) en el pre-compost para la producción de biogás y biol en biodigestores tipo Batch