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Milk House Wastewater Design Guide

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

Introduction

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

The Minnesota Pollution Control Agency currently does not regulate the design, construction or inspection of milk house wastewater treatment systems under Chapter 7080 or specifically under the feedlot rules Chapter 7020. However, milk house wastewater can be a significant pollution hazard that cannot be discharged into the waters of the state. The University of Minnesota has conducted a significant amount of research on alternative treatment and disposal systems for milk house wastewater. This design guide will aid in milk house wastewater treatment system selection, design and siting. Three systems are discussed in this guide. All three systems include a primary septic tank prior to the treatment systems discussed, which are:

• Bark Beds: A large soil infiltration area covered by wood or bark shreds;
• Aerobic Treatment Units (ATUs) or Recirculating Media Filtration (RMF) followed by subsoil infiltration area;
• Frequent (typically daily) irrigation to pasture or cropland.

Milking equipment cleaning.

Bulk tank cleaning.

Other feasible milk house wastewater handling options NOT covered in this design guide include temporary storage with land application, chemical flocculation, and dosing systems to a vegetative treatment area.

Storage and land application options are acceptable methods of milk house wastewater disposal provided that the effluent is applied to cropland in accordance with Chapter 7020. Chemical flocculation and dosing systems are still in the experimental phase of development and can be installed on a case by case basis.

Note also that this design guide DOES NOT address the handling, treatment and disposal of effluent from milking parlors using Bark Beds or Aerobic treatment. The cleaning of milking parlors, flat parlors, step up parlors, herringbone, parallel, swing, rotary parlors, etc., generate significantly amounts of wastewater (per cow) with high concentrations of solids and nutrients. Irrigation systems have been designed and constructed to handle this wastewater but more data on these systems are needed. Methods to handle this stronger waste are currently under development.

This design guide also DOES NOT address the treatment and disposal of colostrum from fresh cows and waste milk from treated cows or other large milk discharges (i.e. bulk tank failures). This waste milk should be disposed of with the manure handling system or separately from any treatment option discussed in this publication.

If human waste is added to the milk house waste, the dispersal system must be designed according to MN Chapter 7080 rules that deal with household septic systems. The systems presented here are not designed to meet MN Chapter 7080 rules for household septic systems.

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