EFFECTIVENESS OF LIQUIDSOLID SEPARATION FOR TREATMENT OF FLUSHED DAIRY MANURE: A CASE STUDY

Abstract

Sunny Day Farm was the home of the highest producing registered Jersey herd in the world at the time this studywas conducted. The cows are housed in a freestall barn and manure is removed from the barn using a flush system. The manuretreatment system on this farm includes the following components in series: an inclined stationary screen separator, atwochambered settling basin, and a lagoon. Samples were taken to quantify the performance of the existing manure treatmentsystem. The inclined stationary screen separator removed 60.9% of the total solids, 62.8% of the volatile solids, 49.2% ofthe TKN, 52.2% of the organicN, and 53.1% of the total P. The complete onfarm manure treatment system removed 93.0%of the TS, 95.6% of the VS, 74.0% of the TKN, 91.1% of the organicN, and 86.1% of the total P. In addition, settlingexperiments were carried out with flushed manure (unscreened) and effluent from the mechanical separator (screened) todetermine how well settling of dairy manure could be enhanced with a polymer (PAM) and aluminum sulfate. Addition of250 to 400 mg PAM/L to screened and unscreened dairy manure significantly increased the removal of total and volatile solids,organicN, total P, Cu, and Zn. The optimum amount of PAM to add was 300 mg/L for screened and unscreened manure.Settling of flushed dairy manure for 60 min following an application of 300 mg PAM/L removed 76.1% of the TS, 80.3% ofthe VS, 80.8% of the COD, 45.7% of the TKN, 72.3% of the organicN, and 61.8% of the total P. The largest amount of TKNand total P was removed by a twostage separation process that combined the stationary inclined screen separator followedby gravity settling with a polymer or aluminum sulfate. Enhancing the gravity stage with 300 mg PAM/L removed 71.1% ofthe TKN and 86.0% of the P. Application of 3,194 mg alum/L removed 71.1% of the TKN and 99.6% of the total P.