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Title: COMPARISON OF BACTERIAL POPULATIONS AND CHEMICAL COMPOSITION OF DAIRY WASTEWATER HELD IN CIRCULATED AND STAGNANT LAGOONS

Author
item McGarvey, Jeffery - Jeff
item Miller, William - Bill
item SANCHEZ, SUSAN - UNIVERSITY OF GEORGIA
item Silva, Christopher - Chris
item Whitehand, Linda

Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2005
Publication Date: 3/19/2005
Citation: Mcgarvey, J.A., Miller, W.G., Sanchez, S., Silva, C.J., Whitehand, L.C. 2005 Comparison of bacterial populations and chemical composition of dairy wastewater held in circulated and stagnant lagoons [abstract]. Journal of Applied Microbiology. 99(10):867-877.

Interpretive Summary: Dairy wastewaters are commonly treated in two ways, stagnation and circulation. Little is known about how these processes effect the types of bacteria that live in these wastewaters or what types of chemicals are present. Using chemical and microbiological techniques we determine the type of bacteria and chemicals present in these systems.

Technical Abstract: High intensity dairy farms produce large amounts of liquid waste that is stored in waste water holding lagoons. The use of circulators to treat waste water is becoming common, and vendors claim that these systems reduce odors, pathogen levels, and alter the chemistry of the waste water such that it is superior to that of stagnant systems for use as a fertilizer for crop plants and in hydraulic flush waste removal applications; however, no scientific studies have been conducted to validate these claims. We characterized 11 chemical and 6 physical parameters of circulated and stagnant waste water over the course of one year to determine the effect of circulation. We also characterized the bacteriological community structure of circulated and stagnant waste waters using culture-based and non-culture-based methods. We observed no significant difference in any of the chemical or physical parameters tested; however, we did observe differences in the bacteriological community structure. Specifically, we observed a 5.4-fold increase in the phylum Chloroflexi (green sulfur bacteria) and a 5.3-fold increase in the phylum Spirochaetes in the stagnant system. We also observed a 4.6-fold increase in the class g-Proteobacteria in the circulated system, which was predominantly due to a > 6-fold increase in the family Chromatiaceae (purple sulfur bacteria), some of which are known to degrade volatile organic acids (VOAs). These findings suggest that although circulation does not effect any of the chemical or physical parameters that we tested, it does alter the microbial community structure and may effect VOA emission.