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Extension > Agriculture > Manure Management and Environmental Quality > Wastewater systems > Milk house wastewater treatment demonstration project overview

Milk house wastewater treatment demonstration project overview

K. A. Janni, S. H. Christopherson and D. R. Schmidt

Full version (361 K PDF)


Minnesota regulations (Minnesota Rules Chapter 7020) restrict milk house wastewater discharges into waters of the state, whether through overland flow or through subsurface tile lines. Subsequently, dairy producers using solid manure handling systems must have a separate system to handle this wastewater. Because milk house wastewater has high concentrations of organic material, fats, and nutrients, standard septic systems are not a viable option. Prior to this project, the only real options available were short or long term storage with land application.

The objective of this project was to develop and test alternative milk house waste handling systems. For this project, 16 milk house wastewater treatment systems were installed and monitored in four counties in Minnesota. Experience and monitoring results from these sites was used to develop design and management guidelines for these alternative systems. Information from the projects was distributed through tours, presentations, fact sheets, a design guide and refereed publications. Many materials are available on the project website.

Recirculating Media Filter

Recirculating Media Filter [click to enlarge]

Which wastewater treatment options were studied?

Four wastewater treatment systems were studied. They were:

Finished bark system

Finished bark system.

Other options available to dairy producers but not studied include chemical flocculation with the treated effluent discharged into a soil infiltration area (drainfield), constructed wetlands and vegetative filter areas using a dosing system. Commercial chemical flocculation systems are available and have been installed in Wisconsin, Minnesota, Canada and elsewhere with success. Constructed wetlands have been used in Wisconsin with limited success. Dosing systems have been used in other states for feedlot runoff treatment but not for milk house wastewater treatment.

Aerobic Treatment

Aerobic Treatment

Summer Irrigation on corn field

Summer Irrigation on corn field

What types of farms were these treatment systems tested on?

Fourteen farms had stall barns with pipeline milking systems. Two farms had parlors with parlor wastewater mixed in with the milk house wastewater. Milking herd sizes ranged from 40 to 130 cows.

What was included in the wastewater?

Milk house wastewater includes wash water from cleaning bulk tanks, milk pipelines, milking units, miscellaneous equipment, and the milk house floor. Milk house wastewater commonly includes residual milk (i.e. milk that remains in the pipeline, receiver, and bulk tank after emptying), cleaning chemicals (i.e. detergents, sanitizers and acid rinses), water softener recharge water, and small amounts of manure, bedding, feed, grit and dirt.

Wastewater from milking systems which combine parlor wastewater with milk house wastewater has more manure and larger volumes of wastewater. Toilet wastes were not included. A separate treatment system is needed for toilet wastewater due to pathogen concerns and subsequent regulations.

Who funded the project?

Two US EPA 319 grants administered through the Minnesota Pollution Control Agency provided almost half of the funding for the project. Significant matching and in-kind funds were obtained from other state and local agencies and the cooperating dairy producers.

What were the results of the project?

Which system is best for me?

All of the systems studied, can be effective when designed and managed appropriately. 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 wasters. Producer preference and management are important factors when selecting a system.

Where can I get additional Information

For additional information visit or contact your local Extension office.

Publication 1205

Funding for this project was provided to the Bioproducts and Biosystems Engineering Department through two US EPA 319 grants administered by the Minnesota Pollution Control Agency. Additional significant matching funding was provided by other state and local agencies and the cooperating dairy producers. The purpose of the project was to design, install and monitor sixteen milk house wastewater treatment systems in four counties in Minnesota. The results were used to develop design and management guidelines. Additional information.

This fact sheet was updated September 2007.

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