Evaluation and Demonstration of Treatment Options for Dairy Parlor and Milk House Wastewater

Four different types of milk house wastewater treatment systems were installed on working dairy farms varying in size from 50-130 cows. The treatment systems demonstrated include two types of aerobic treatment units; two bark beds and spray irrigation. All of the systems include a primary treatment septic tank. In addition to system performance, design, management and economic aspects are being evaluated. Water flow data was collected on eleven farms for one year with a range of a flow rates from 360 to 1670 liters/day (L/d) (95 - 441 gallons per day (gpd)) or from 11.0 – 24.2 L/d/cow (2.9 – 6.4 gpd/cow). Preliminary influent data has shown an average BOD5 of 2220 mg/L, COD of 3360 mg/L, TSS of 1030 mg/L and FOG (Fats, Oils and Grease) of 650 mg/L. The aerobic treatment units preliminary removal efficiencies for BOD5, COD, TSS, and FOG ranged from 44-94%, 32-94%, 61-82%, and 71-98%, respectively. The bark bed systems have worked without a problem although water samples from within the beds have not yielded sufficient quantities for analysis. The irrigation system did experience some freezing and odor issues but continued to operate through the winter. The average equipment and installation cost was nearly $10,000 with a range of $6,200 - $14,400. Challenges have arisen with higher than expected organic loading, colder than normal temperatures with little snow cover.