U of M study recommends four milk house wastewater systems

By Kevin Janni, University of Minnesota Extension

ST. PAUL, Minn. (1/28/2008) —Wastewater from milk houses can’t be discharged into the waters of the state, according to Minnesota regulations. This means dairy farmers using solid waste manure handling systems must have a separate system to handle this wastewater.

Milk house wastewater has high concentrations of organic material, fats and nutrients; so standard septic systems are not a viable option. Milk house wastewater includes wash water from cleaning bulk tanks, milk pipelines, milking units and the milk house floor. It includes residual milk left in the system, cleaning chemicals, water softener recharge water and small amounts of bedding, feed, grit and dirt.

Before a University of Minnesota research project was completed, the only real options available were short- or long-term storage with land application.

The U of M study involved installing and monitoring wastewater treatment systems on 16 dairy farms in four Minnesota counties. The four systems studied were:

• Bark beds—large soil infiltration areas covered by wood or bark shreds.
• Aerobic treatment units followed by a subsoil infiltration area.
• Recirculating media filters followed by a subsoil infiltration area.
• Daily surface irrigation to pasture or cropland.

All four systems studied were effective at treating milk house wastewater. The systems studied were not designed to treat waste milk. System costs ranged from $6,700 to $25,000.

For dairy producers, choosing the right system is a matter of water usage, farm layout, site geography, soil types, depth to ground water or bed rock and proximity to surface waters. Producer preference and management are important factors when selecting a system.

Almost half of the project funding came from EPA grants administered through the Minnesota Pollution Control Agency. Matching and in-kind funds came from other state and local agencies and the cooperating dairy producers.

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URL: http:// www.extension.umn.edu/extensionnews/2008/milkhousewastewater.html  This page was updated Jan. 28, 2008 .
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