2002 Annual Report
Research
Potential Leachate and Porosity Change of Biofilter Media After Heavy
Rainfall
Jun Zhu, Assistant Professor, Southern
Research and Outreach Center, Waseca, MN
Curtis Miller, Assistant Scientist, Southern Research and Outreach Center,
Waseca, MN
Zhijian Zhang, Post-Doctoral Associate, South Research and Outreach Center,
Waseca, MN
Funding Source
Minnesota Corn Growers Association
Objective
The objectives of the project include: 1) determine if there are potential
leaching problems from the biofilter bed media. If yes, determine the
chemical and biological nature of the leachates and 2) determine the time
needed for the biofilter media to recover to normal operating moisture
level after being washed by various rainfall amounts.
Project Description
The biofilter of the swine gestation facility at the Southern Research
and Outreach Center at Waseca was used in the experiment. Collection pens
(3’x3’) were placed underneath the biofilter media. Artificial
rainfall of 3”, 6”, and 9” within a 24-hour period was
employed to examine the possible leachate through the biofilter media.
The leachate collected was analyzed for nitrogen (total, ammonium, and
nitrate), phosphorus, pH, and total solids.
Results
According to the data collected so far, no leachate was collected under the 3” precipitation condition, indicating that no concerns about nutrient leaching would be necessary for rainfall of less than 3” in a 24-hour period. In addition, the media moisture content was not noticeably affected by the treatment so it might be concluded that 3” rainfall in a 24-hour period would not impart much impact on biofilter performance. Data on the other two treatments, i.e., 6” and 9” rainfall are not available as of this date.