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Title: Bacterial community dynamics in surface flow constructed wetlands for the treatment of swine waste

Author
item Ibekwe, Abasiofiok - Mark
item MA, JINCAI - Jilin University
item MURINDA, SHELTON - California Polytechnic State University
item REDDY, G. - North Carolina Agricultural And Technical State University

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/26/2015
Publication Date: 12/2/2015
Citation: Ibekwe, A.M., Ma, J., Murinda, S., Reddy, G.B. 2015. Bacterial community dynamics in surface flow constructed wetlands for the treatment of swine waste. Science of the Total Environment. 544:68-76. doi: 10.1016/j.scitotenv.2015.11.139.

Interpretive Summary: Constructed wetlands are sometimes used for the treatment of wastewaters from a variety of sources. It is a cost effective method for waste decontamination from different sources. Therefore, this system was used in a pilot study to determine the effectiveness of waste decontamination from swine waste water. Traditionally, in the swine production system wastes are flushed into an anaerobic lagoon and then later sprayed on agricultural fields. This may have some unintended consequences like polluting surface waters, contaminating wells, creating noxious odors, and discharging ammonia into the air. In this study, we compared the composition of microbial communities in time and space in a marsh-pond-marsh (MPM) surface flow constructed wetland used for the treatment of swine waste using a new DNA sequencing technology. Our results showed that the wetland system is very rich in bacterial composition, and this may be the major reason why most wetlands are very efficient in waste decomposition. This information will be of interest to swine farmers, government and non-government organizations, as well as other livestock producers in both developed and developing countries.

Technical Abstract: Constructed wetlands are generally used for the removal of waste from contaminated water. In the swine production system, wastes are traditionally flushed into an anaerobic lagoon which is then sprayed on agricultural fields. However, continuous spraying of lagoon wastewater on fields can lead to high N and P accumulations in soil or may contaminate surface or ground water with pathogens. Using a 454/GS-FLX pyrosequencing, we assessed bacterial composition within a surface flow constructed wetland over a 12-month period to determine temporal and spatial dynamics of bacterial communities within the wetland. The results were analyzed using UniFrac, coupled with principal coordinate analysis (PCoA) to compare diversity, abundance, community structure, and specific functional groups of bacteria in the manure influent, lagoon, storage tank, wetland cells, storage pond, and the final effluent. PCoA analysis showed that bacterial composition from manure influent and lagoon water were significantly different (P = 0.0001), both on the spatial and temporal scales from the storage pond and the final effluent. Canonical correspondence analysis (CCA) of wetland microbial community showed that bacterial populations were significantly shaped by NH4 (P = 0.035), PO4 (P = 0.010), COD (P = 0.0165), TS (P = 0.030), and DS (P =0.030), with 54 % of the variations explained by NH4+PO4 according to a partial CCA – based variation partitioning analysis. From all the sampling points, bacteria were numerically dominated by phyla—the Proteobacteria (34.64%), Bacteroidetes (22.04%), Firmicutes (9.86%), Cyanobacteria (6.22%), and Actinobacteria (2.69%) accounting for the majority of taxa detected. Our results showed that the wetland system is very rich in bacterial composition (> 27 phyla), and this may be the major reason why most wetlands are very efficient in waste decomposition.