Differences in microbial communities and pathogen survival between a covered and uncovered anaerobic lagoon

Authors: Ducey, Thomas; RASHASH, DIANA - North Carolina Cooperative Extension; Szogi, Ariel

Submitted to: Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2019
Publication Date: 8/6/2019
Citation: Ducey, T.F., Rashash, D., Szogi, A.A. 2019. Differences in microbial communities and pathogen survival between a covered and uncovered anaerobic lagoon. Environments. 6(10):109. https://doi.org/10.3390/environments6100109.
DOI: https://doi.org/10.3390/environments6100109

Interpretive Summary: For swine production operations, waste is traditionally stored in large earth basins called lagoons. These lagoons rely on anaerobic (i.e., no oxygen) conditions to treat and store the wastewater prior to land application. In order to reduce odors, operators can outfit these lagoons with synthetic covers. While these covers are often employed, there has been very little research into how these lagoons affect the physical, chemical, and biological characteristics. To address this issue, we studied two swine production systems, one of which employed a cover, and the other which utilized a traditional, open lagoon. Results indicated that pathogen indicators were influenced by the use of a cover. Sequencing of the microbial communities also indicated that the use of a cover also influenced microbial populations, with changes in pH, total nitrogen, suspended solids, as well as the ions chloride, sodium, and potassium, serving as major environmental variables driving differences amongst the microbial communities. Overall these results demonstrate that permeable synthetic covers play a role in changing the lagoon microclimate that results in changes to the lagoons physicochemical and biological characteristics.

Technical Abstract: Anaerobic lagoons are a critical component of confined swine feeding operations. These structures can be modified, using a synthetic cover, to enhance their ability to capture the emission of ammonia and other malodorous compounds. Very little has been done on assessing the potential of these covers to alter lagoon biological properties. Alterations in the physicochemical makeup can impact the biological properties, most notably the pathogenic populations. To this aim we performed a seasonal study of two commercial swine operations, one with a conventional open lagoon, the other which employed a permeable, synthetic cover. Results indicated that lagoon fecal coliforms, and Escherichia coli were significantly influenced by sampling location (lagoon vs house) and lagoon type (open vs covered), while Enterococcus sp. were influenced by sampling location only. Comparisons against environmental variables revealed that fecal coliforms (r2 = 0.40), E. coli (r2 = 0.58), and Enterococcus sp. (r2 = 0.25) all significantly responded to changes in pH. Deep 16S sequencing of lagoon and house bacterial and archaeal communities demonstrated grouping by both sampling location and lagoon type, with several environmental variables correlating to microbial community differences. Overall these results demonstrate that permeable synthetic covers play a role in changing the lagoon microclimate, impacting lagoon physicochemical and biological properties