Pig and piglet.

2016-17 Rapid Ag: Mechanism Study of Manure Foaming in the Swine Pit Storage

April 1, 2016

Principle Leader

Bo Hu


Department of Bioproducts & Biosystems Engineering

Funding Awarded

  • 2016 Fiscal Year: $81,794
  • 2017 Fiscal Year: $84,779

The Problem

Foaming in swine manure pits has become a serious issue in Minnesota, Iowa and Illinois since 2008-2009 as it reduces manure storage capacity and, more importantly, has led to explosions by the methane gas trapped in the foam. Decreasing the incidence of foaming is critical to pork producers in the Midwest from both safety and economic perspectives.


A survey done by Hu's UMN research group in 2010 showed that 25% of barns in MN had this issue, and it caused widespread panic reactions among farmers, insurance and general public. Since then, multiple theoretical research methodologies and industrial applications have been tested both in the lab and in the field. The reported foaming cases have dropped significantly in the year 2013-14, when multiple defoamer or anti-foamer products, for instance, monensin, are widely added in the manure pit or some farmers added bacillus strains to feed (U.S. Patent 8557234) in order to eliminate or prevent foaming. This was also coincident with the transformation of ethanol industry here that oil is extracted from the dominant feeding material, DDGS. Foaming seems to re-emerge in the year of 2015, even though not as serious or widespread as it was five years ago, and it has already caused multiple explosions, even death of two workers in a southern MN Hog farm in the middle of this year. It is still a mystery about the reasons that foaming generates and ceases. Reducing foam with anti-foam products or limiting foam formation with manure and feed additives have been implemented with varying results. Unfortunately, the success of these treatments is unpredictable and is always an additional cost for pork producers. To prevent the next bloom of foaming which may happen in swine manure pits, it is worthwhile to have an investigation on the foaming inducer, understand the mechanisms of manure foaming and develop some specific mitigation or prevention strategies.


  1. Study the differences between foaming and non-foaming manure based on our newly developed sampling protocols on all layers of pit storage.
  2. Simulate the manure storage in the lab to verify the currently proved approaches to induce or eliminate foaming, and therefore, to reveal the fundamental mechanisms of the manure foaming.
  3. Provide foundations to develop permanent approaches to control or eliminate the foaming.
Bo Hu.

Bo Hu works to unravel the cause of, and develop solutions for, foaming manure in swine manure pits in his lab on the Saint Paul campus.