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United States Department of Agriculture

Agricultural Research Service

Title: Effectiveness of Liquid-Solid Separation for Treatment of Slushed Dairy Manure: a Case Study

Authors
item Chastain, J - CLEMSON UNIV.
item Vanotti, Matias
item Wingfield, M - CLEMSON UNIV.

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 5, 2000
Publication Date: N/A

Interpretive Summary: Interest has greatly increased in removing solids and nutrients from dairy manure. Depending on the magnitude of this removal process, it may be possible to develop new treatment systems that rely less on the use of treatment lagoons. Compared with liquid forms, the transport of nutrients off the farm in solid forms is more easy and much less expensive. In addition, the nutrient load on the farm is reduced which may be critical to manage new land application guidelines based on phosphorus (P) requirements. In this study we evaluated the use of the polymer polyacrylamide (PAM) in either one or two stage process combinations to enhance the separation by screens and gravity settling. The farm in the study is home of the highest producing Jersey herd in the world. It uses a freestall barn, a flushing system, and a treatment series consisting of an inclined stationary screen separator, a settling basin, and an anaerobic lagoon. Addition of PAM to dairy manure (containing 42000 ppm solids) significantly increased the removal of solids, organic-N, total P, and heavy metals copper (Cu) and zinc (Zn). Metals are also an environmental concern when applied in excessive amounts to land. The system worked best using a two-stage separation process that combined the stationary inclined screen separator followed by polymer application (300 mg/L) and gravity settling. It removed 92.4% of the total solids,93.5% of the oxygen demand (COD), 71.1% of the total nitrogen, 86.0% of the total phosphorus and 92% of the Zn and Cu. These high removal efficiencies were obtained without the use of a lagoon, indicating that enhanced separation technology can be useful for development of alternative systems.

Technical Abstract: Sunny Day Farm is the home of the highest producing registered Jersey herd in the world. The cows are housed in a freestall barn and manure is removed from the barn using a flush system. The manure treatment system on this farm includes the following components in series: an inclined stationary screen separator, a two-chambered settling basin, and a lagoon. Samples were taken to quantify the performance of the existing manure treatment system. The inclined stationary screen separator removed 60.9% of the total solids, 62.8% of the volatile solids, 49.2% of the TKN, 52.2% of the organic-N, and 53.1% of the total P. The complete on-farm manure treatment system including the lagoon removed 93.0% of the TS, 95.6% of the VS, 74.0% of the TKN, 91.1% of the organic-N, and 86.1% of the total P. In addition, settling experiments were carried out with flushed manure (unscreened) and effluent from the mechanical separator (screened) to determine how well settling of dairy manure could be enhanced with polymers (PAM). Addition of PAM to screened and unscreened dairy manure significantly increased the removal of total and volatile solids, organic-N, total P, Cu and Zn. Settling of flushed dairy manure for 60 min following an application of 300 mg PAM/L removed 76.1% of the TS, 80.3% of the VS, 80.8% of the COD, 45.7% of the TKN, 72.3% of the organic-N, and 61.8% of the total P. Higher efficiencies were obtained by a two-stage separation process that combined the stationary inclined screen separator followed by gravity settling with 300 mg PAM/L polymer. It removed 92.4% of the TS, 71.1% of the TKN and 86.0% of the P. This indicates that polymer treatment can replace use of treatment lagoons.

Last Modified: 9/22/2014
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