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United States Department of Agriculture

Agricultural Research Service

Research Project: Assessing Atmospheric Emissions from Concentrated Animal Feeding Operations in the Pacific Northwest

Location: Northwest Irrigation and Soils Research

Title: Effect of sprinkler pressure and spray plate on culturable microorganism concentrations during simulated irrigation of dairy wastewater

Authors
item Dungan, Robert
item Bjorneberg, David
item Leytem, April

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 19, 2011
Publication Date: November 1, 2011
Citation: Dungan, R.S., Bjorneberg, D.L., Leytem, A.B. 2011. Effect of sprinkler pressure and spray plate on culturable microorganism concentrations during simulated irrigation of dairy wastewater. Transactions of the ASABE. 54(5):1669-1673.

Interpretive Summary: A simulated spray irrigation study of dairy wastewater was conducted to assess the impact of pressure and sprinkler type upon post-sprinkler culturable microorganism concentrations. Three different sprinklers types were used at three different operating pressures to give a range of water drop sizes. In most cases the pre- and post-sprinkler concentrations were determined to be statistically similar, suggesting that culturable viability was not affected when wastewater flowed through these sprinklers. When an impact was found to occur, there was usually an increase in the post-sprinkler microorganism concentration suggesting that microbial aggregates were being disrupted. It is important to understand sprinkler impacts on microorganisms, as it may influence the number of viable organisms that become aerosolized during pressured irrigation events. Once aerosolized, the microorganisms can be transported offsite and are also a potential health risk.

Technical Abstract: In this study we conducted simulated spray irrigation events of dairy wastewater to assess the impact of pressure and sprinkler type upon post-sprinkler culturable microorganism concentrations. Dairy wastewater was sampled before and after it was pumped through sprinklers typically used on center pivot irrigation systems. Three different sprinklers types were used at three different operating pressures to give a range of water drop sizes. The microorganisms quantified in this study were total coliforms, Escherichia coli, Clostridium perfringens, heterotrophic bacteria, and coliphage. In most cases the pre- and post-sprinkler concentrations were determined to be statistically similar, suggesting that culturable viability was not affected when wastewater flowed through these sprinklers. When an impact was found to occur, there was usually an increase in the post-sprinkler microorganism concentration. While this increase can be attributed to the disruption of microbial aggregates during the spraying process, there was no apparent relationship with pressure setting or spray plate. Understanding impacts at the sprinkler-level should be considered an integral part of the dispersion modeling process, as it may influence the number of viable microorganisms that become aerosolized during pressurized irrigation events.

Last Modified: 4/24/2014
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