BACTERIAL AND CHEMICAL COMPOSITION OF DAIRY WASTEWATER

Authors: McGarvey, Jeffery - Jeff; Miller, William - Bill; SANCHEZ, SUSAN - UNIV. OF GEORGIA; Silva, Christopher - Chris

Submitted to: American Society for Microbiology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/5/2005
Publication Date: 6/5/2005
Citation: Mcgarvey, J.A., Miller, W.G., Sanchez, S., Silva, C.J. 2005. Bacterial and chemical composition of dairy wastewater [abstract]. American Society for Microbiology General Meeting, 6/5-6/9/05, Atlanta, GA. P. 008.

Interpretive Summary: Dairy farms generate large amounts of liquid waste that is held in lagoons. Some farms are starting to use circulators to mix the waste waters and believe that this is helpful in many ways. We compared circulated and stagnant dairy wastewater lagoons for gross microbiological, 11 chemical and 6 physical parameters and found no difference. We did see differences in the types of bacteria present, most notably a family of bacteria called the Chromatiaceae or purple sulfur bacteria are more numerous in the circulated lagoons, some of which are known to degrade volatile organic chemicals. We also noted increases in bacteria phyla Cloroflexi and Spirochaetes in the stagnant lagoons. Thus circulation did not effect any of the gross microbiological, chemical or physical parameters but did alter the bacterial community structure.

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 ''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.