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

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.