Persistence of pathogens in liquid pig manure processed in manure tanks and biodigesters

ABSTRACT Objective. To evaluate the persistence of virus, bacteria, mold, yeast and parasites in liquid pig manure, processed in biodigesters and manure tanks in the central-western part of Colombia. Materials and methods. A directed observational study analyzed descriptively was carried out in three pig farms located where the manure tanks were assembled and its biodigesters were used. A sampling of liquid pig manure was taken to assess the presence of 26 pathogens at the beginning of the study and another one at the end of the process in manure tanks and biodigesters. For the manure tank, a 250 liters tank was filled with fresh pig manure and was analyzed after three days of storage. The biodigesters were of continuous flow and its effluents were analyzed, according to the specific hydraulic retention times. The diagnostic techniques were those recommended specifically for each microorganism and were carried out in certified labs by the Colombian Animal Health authority. Results. Of the 26 pathogens that were investigated, 15 appeared in the fresh pig manure used in pig manure tanks and 12 in the one used in biodigestors. In manure tanks, Porcine Circovirus type 2 (PCV2), mold, yeast, Salmonella spp., Balantidium coli and Strongylids did not persist. In biodigesters, PCV2, yeast, Strongylids, B. coli and Strongyloides spp., did not persist. Conclusions. In both manure tanks and biodigesters, a variation could be seen in pathogen persistency, indicating that they act as transformation systems of pig manure for the removal of the latter, as long as the storage times are increased if the efficiency wants to be improved. RESUMEN Objetivo. Evaluar la persistencia de virus, bacterias, mohos, levaduras, y parásitos en porcinaza líquida, procesada en biodigestores y tanques estercoleros en el centro–occidente de Colombia. Materiales y Métodos. Se realizó un estudio de observación dirigida analizada descriptivamente en tres explotaciones porcinas, donde se montaron tanques estercoleros y se aprovecharon sus biodigestores. Se realizó un muestreo de porcinaza fresca para analizar la presencia de 26 patógenos al comienzo del estudio y otro al final del proceso de estercoleros y biodigestores; los muestreos se repitieron en dos momentos en las tres granjas. Para el estercolero, se llenó un tanque de 250 litros con porcinaza fresca y se analizó después de tres días de almacenamiento. Los biodigestores fueron de flujo continuo, y se analizaron sus efluentes, según los tiempos de retención hidráulica específicos. Las técnicas diagnósticas fueron las recomendadas específicamente para cada microorganismo y se ejecutaron en laboratorios certificados por la autoridad sanitaria colombiana. Resultados. De los 26 patógenos investigados se detectaron 15 en la porcinaza fresca usada en estercoleros y 12 en la utilizada en biodigestores. En tanques estercoleros Circovirus Porcino tipo 2 (PCV2), mohos, levaduras, Salmonella spp., Balantidium coli y estrongilidos no persistieron. En biodigestores PCV2, levaduras, estrongilidos, B. coli y Strongyloides spp., no persistieron. Conclusiones. Tanto en estercoleros como biodigestores se observó variación en la persistencia de agentes patógenos, indicando que funcionan como sistemas de transformación de la porcinaza para la remoción de éstos, siempre y cuando se aumenten los tiempos de almacenamiento si se quiere mejorar su eficiencia