Co-digestión anaerobia de la fracción orgánica de residuos sólidos urbanos y su lixiviado / Anaerobic co-digestion of the organic fraction of urban solid waste and its leachate

RESUMEN Los residuos sólidos urbanos (RSU), al ser vertidos sin tratamiento apropiado, ocasionan daños severos al medio ambiente influyendo en la calidad de vida de la población; por esta razón actualmente se le presta atención al adecuado manejo de estos residuos. En este trabajo se estudia la reducción de la fracción orgánica (FORSU), de residuos sólidos generados por un grupo poblacional, tomando como referente una de las residencias estudiantiles de la Universidad de Oriente. La generación de FORSU en la residencia es de 0,06 kg/habdía, con un contenido de sólidos totales de 30,9 ± 5,3 %, de los cuáles el 81,7 ± 0,6 % son sólidos volátiles. Se evalúa la digestión anaerobia la FORSU, mediante un sistema de tratamiento en dos etapas. La primera etapa se realiza en un reactor en lote de lecho escurrido, que permitió un tratamiento discontinuo e in situ de la FORSU, en co-digestión anaerobia con un 25 % de estiércol vacuno. En una segunda etapa, se evalúa el tratamiento anaerobio para los lixiviados que se generan en el reactor en lote, empleando un reactor UASB. En el reactor en lote se alcanzó una remoción de sólidos volátiles del 44,1 %, mientras que en el reactor UASB se removió un 81,2 % de DQO. Como resultado la evaluación del sistema de tratamiento, se alcanzó una productividad total de 5,37 LCH4-kgSV -1-d-1.

ABSTRACT Urban solid waste (MSW), when are discharged without proper treatment, causes severe damage to the environment, influencing the population's quality of life. For this reason, attention is currently paid to the proper handling of this waste. This paper studies the reduction of the organic fraction of solid waste (OFMSW), generated by a population group, taking as reference one of the Student Residences of the Universidad de Oriente. The generation of OFMSW in the residence is 0.06 kg/inhabday, with a total solid content of 30.9 ± 5.3%, of which 81.7 ± 0.6% are volatile solids. The anaerobic digestion of OFMSW is evaluated through a two-stage treatment system. The first stage is performed in a drained-bed batch reactor, which allowed discontinuous and in-situ treatment of OFMSW, in anaerobic co-digestion with 25% of cow manure. In a second stage, the anaerobic treatment for the leachates generated in the batch reactor is evaluated, using a UASB reactor. In the batch reactor a removal of volatile solids of 44.1% was achieved, while in the UASB reactor 81.2% of COD was removed. As a result of the evaluation of the treatment system, total productivity of 5.37 L CH4 -kgSV -1-d-1 was achieved.

Micromonospora fluminis sp. nov., isolated from mountain river sediment.

During a bioprospection of bacteria with antimicrobial activity, the actinomycete strain A38T was isolated from a sediment sample of the Carpintero river located in the Gran Piedra Mountains, Santiago de Cuba province (Cuba). This strain was identified as a member of the genus Micromonospora by means of a polyphasic taxonomy study. Strain A38T was an aerobic Gram-positive filamentous bacterium that produced single spores in a well-developed vegetative mycelium. An aerial mycelium was absent. The cell wall contained meso-diaminopimelic acid and the whole-cell sugars were glucose, mannose, ribose and xylose. The major cellular fatty acids were isoC15:0, 10 methyl C17:0, anteiso-C17:0 and iso-C17:0. The predominant menaquinones were MK-10(H4) and MK-10(H6). Phylogenetic analysis of 16S rRNA gene sequences revealed that this strain was closely related to Micromonospora tulbaghiae DSM 45142T (99.5 %), Micromonospora citrea DSM 43903T (99.4 %), Micromonospora marina DSM 45555T (99.4 %), Micromonospora maritima DSM 45782T (99.3 %), Micromonospora sediminicola DSM 45794T (99.3 %), Micromonospora aurantiaca DSM 43813T (99.2 %) and Micromonospora chaiyaphumensis DSM 45246T (99.2 %). The results of OrthoANIu analysis showed the highest similarity to Micromonospora chalcea DSM 43026T (96.4 %). However, the 16S rRNA and gyrB gene sequence-based phylogeny and phenotypic characteristics provided support to distinguish strain A38T as a novel species. On the basis of the results presented here, we propose to classify strain A38T (=LMG 30467T=CECT 30034T) as the type strain of the novel species Micromonospora fluminis sp. nov.

Evaluación del tratamiento anaerobio de las aguas residuales de una comunidad universitaria / Evaluation of the anaerobic treatment of domestic wastewaters of a university campus

En las universidades cubanas más del 65 % de los estudiantes son becarios y se presta especial atención a la gestión de las aguas domésticas generadas en las comunidades y residencias universitarias. Este trabajo presenta la remoción de la materia orgánica en las aguas domésticas de la comunidad universitaria Antonio Maceo de la Universidad de Oriente empleando, a escala de laboratorio, dos sistemas: reactor UASB y laguna anaerobia. Los sistemas anaerobios evaluados, alcanzaron una remoción de la DQO superior al 70 % y una disminución de las bacterias coliformes totales desde 72x10(5) NMP/100 mL hasta 16 NMP/100 mL. La clarificación con alumbre mejora las características estéticas del efluente. Cualquiera de las variantes (UASB o laguna anaerobia) pueden ser aplicadas para la remoción de la materia orgánica en las aguas domésticas de la comunidad universitaria.

At cubans universities over the 65 % of students are grant holders and special attention lends itself to the steps of domestic waters generated in communities and university permanences. This work presents the removal of the organic matter in the university community's domestic waters Antonio Maceo of the Universidad de Oriente utilizing, to scale of laboratory two systems: UASB reactor and anaerobic lagoon. The anaerobic systemsevaluated attained a superior COD removal to the 70 % and decrease of bacteria's total coliformes from 72x105 NMP/100 mL to 16 NMP/100 mL. The clarification with alum improves the esthetic characteristics of the outflow. Anyone of variants (UASB or anaerobic lagoon) can be applied for the removal of the organic matter in the university community's domestic waters.

Effect of organic loading rate on the performance of two-stage anaerobic digestion of the organic fraction of municipal solid waste (OFMSW).

Two-stage anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) was carried out: hydrolysis and acidogenesis in a continuous anaerobic hydrolytic leach bed (AHLB) reactor loaded at different rates (Bv = 3.8-7 gVSSL⁻¹d⁻¹) and methanogenesis of leachates, diluted with municipal wastewater in an upflow anaerobic sludge blanket (UASB) reactor at organic loading rates of 6.6-13 gCODLr⁻¹d⁻¹. In the AHLB reactor, 51-76% and 58-71% volatile solids and chemical oxygen demand (COD) removal efficiencies were obtained. During the hydrolysis and acidogenesis phases, the effluents were at pH 4.93, the leachate had a volatile fatty acids concentration of 35 g/L and the biogas was composed only of CO2. The average methane production in the UASB in the load of 4.4 gVS L⁻¹ d⁻¹ in the AHLB was 3.32 LCH4Lr⁻¹d⁻¹ (yCH4 = 80%), with COD removal efficiency of 95% and methane yield 279 LCH4KgVS⁻¹OFMSW degraded.

Evaluación de dos métodos de conservación para Kluyveromyces marxianus CCEBI 2011 en la Colección de Cultivos del CEBI / Evaluation of two conservation methods for Kluyveromyces marxianus CCEBI 2011 at the CEBI Culture Collection

La elección de un método de conservación debe permitir mantener, entre otros parámetros, la viabilidad, pureza y estabilidad de las propiedades de una cepa. Kluyveromyces marxianus CCEBI 2011 es una levadura con atractivas potencialidades biotecnológicas, conservada en la Colección de Cultivos del CEBI mediante dos métodos: transferencia periódica y agua destilada estéril (método de Castellani). En este trabajo, para determinar la eficacia y calidad de los dos métodos utilizados para la conservación de K. marxianus CCEBI 2011, se evaluaron parámetros como viabilidad, pureza e identidad y propiedades biotecnológicas. Por ambos métodos se obtuvo una elevada pureza y una viabilidad de 5,31x1010 células/mL y 6,8x1010 células/mL por el método de Castellani y transferencia periódica, respectivamente. En este último se alcanzaron los mayores valores de tolerancia a etanol (11%), producción de etanol (6,08 ± 0,11 g/L) y actividad pectinolítica (15,29 ± 1,71 U/mL). En los dos métodos se corroboró la clasificación taxonómica de esta cepa como K. marxianus, según el análisis de las regiones ITS1-gen 5,8S ARNr-ITS2. Se demostró que los métodos de conservación empleados son efectivos, y que han mantenido con calidad las potencialidades biotecnológicas de este microorganismo por más de 10 años.

The election of a conservation method should allow maintaining, among other parameters, the viability, purity and stability of the properties of a strain. Kluyveromyces marxianus CCEBI 2011 is a yeast with attractive biotechnological potentialities, conserved at the CEBI Culture Collection by two methods: periodic transfer and sterile distilled water (Castellani method). In this study for determining the efficacy and quality of the two methods being used for the conservation of K. marxianus, we evaluated parameters such as viability, purity, identity and biotechnological properties. For both methods we obtained a high purity and a viability of 5.31x1010 cells/mL and 6.8x1010 cells/ mL, for the Castellani method and the periodic transfer method respectively. In this last method we obtained the highest values for ethanol tolerance (11%), ethanol production (6.08 ± 0.11 g/L) and pectonolitic activity (15.29 ± 1.71 U/mL). For the two methods the taxonomic classification of this strain as K. marxianus was corroborated according to the analysis of the ITSI-gen 5.8S ARNr-ITS2 regions. It was shown that the conservation methods being used are effective and that they have maintained the quality of the biotechnological potentialities of this microorganism during more than 10 years.

Decolourisation of mushroom farm wastewater by Pleurotus ostreatus.

Mushroom production on coffee pulp as substrate generates an intense black residual liquid, which requires suitable treatment. In the present study, Pleurotus ostreatus growth in wastewater from mushroom farm was evaluated as a potential biological treatment process for decolourisation as well as to obtain biomass (liquid inoculum). Culture medium components affecting mycelial growth were determined, evaluating colour removal. Laccase activity was monitored during the process. P. ostreatus was able to grow in non diluted WCP. Highest biomass yield was obtained when glucose (10 g/l) was added. The addition of this carbon source was necessary for efficient decolourisation. Agitation of the culture improved biodegradation of WCP as well as fungal biomass production. Laccase and manganese-independent peroxidase activities were detected during fungal treatment of the WCP by P. ostreatus CCEBI 3024. The laccase enzyme showed good correlation with colour loss. Both wastewater colour and pollution load (as chemical oxygen demand) decreased more than 50% after 10 days of culture. Phenols were reduced by 92%.