Wetlands
for treatment of milking center wastewater
Jeff Lefever
Wayne NRCS
How
well do they work? Results on monitoring wetland for
treatment of milking center wastewater
Dr. Tom Zimmerman
ATI/OSU
Treatment
wetlands are an option for treating milkhouse wastewater for dairies with fewer
than 100 cows. The stems of wetland
plans filter suspended solids and provide a substrate for the microorganisms
that can reduce biological oxygen demand (BOD), nitrogen, phosphorus, trace
metals and pathogens. Prior to
construction of a wetland, the topography, soil characteristics, hydrologic
activity, farm enterprise, aesthetics and cultural resources of the site must be
evaluated. Pretreatment of
milkhouse wastewater via a settling basin, lagoon, or dilution may increase the
effectiveness of the wetland to meet target levels of 1,500 milligrams/liter
(mg/l) total solids and 100 mg/l ammonia. The
size required for a treatment wetland may be determined by the evaluating the
BOD produced by the animal and uptake by plants or by maintaining a hydraulic
residence time of at least 12 days.
Surface
flow treatment wetlands were constructed on three small dairy farms (~60 head)
in Wayne County to evaluate the effectiveness of treating milkhouse wastewater.
Wastewater drained to a holding pond on one farm before entering the
wetland while the other two drained directly to the wetland.