title: Centrifuge separation effect on bacterial indicator reduction in dairy manure.
abstract: Centrifugation is a commonly applied separation method for manure processing on large farms to separate solids and nutrients. Pathogen reduction is also an important consideration for managing manure. Appropriate treatment reduces risks from pathogen exposure when manure is used as soil amendments or the processed liquid stream is recycled to flush the barn. This study investigated the effects of centrifugation and polymer addition on bacterial indicator removal from the liquid fraction of manure slurries. Farm samples were taken from a manure centrifuge processing system. There were negligible changes of quantified pathogen indicator concentrations in the low-solids centrate compared to the influent slurry. To study if possible improvements could be made to the system, lab scale experiments were performed investigating a range of g-forces and flocculating polymer addition. The results demonstrated that polymer addition had a negligible effect on the indicator bacteria levels when centrifuged at high g forces. However, the higher g force centrifugation was capable of reducing bacterial indicator levels up to two-log10in the liquid stream of the manure, although at speeds higher than typical centrifuge operations currently used for manure processing applications. This study suggests manure centrifuge equipment could be redesigned to provide pathogen reduction to meet emerging issues, such as zoonotic pathogen control.
authors.affiliation: Dep. of Biological Systems Engineering, Univ. of Wisconsin-Madison, 460 Henry Mall, Madison, WI 53706, United States.
authors.forename: Zong
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Dep. of Civil & Environmental Engineering, Univ. of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53705, United States.
authors.forename: Zachary S
authors.initials: ZS
authors.lastname: Carroll
authors.affiliation: Dep. of Civil & Environmental Engineering, Univ. of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53705, United States; Wisconsin State Laboratory of Hygiene and Dep. of Soil Science, Univ. of Wisconsin-Madison, 1525 Observatory Drive, Madison, WI 53706, United States.
authors.forename: Sharon C
authors.initials: SC
authors.lastname: Long
authors.affiliation: Soil Net LLC, 560 Enterprise Drive, Belleville, WI 53508, United States.
authors.forename: Aicardo
authors.initials: A
authors.lastname: Roa-Espinosa
authors.affiliation: Dep. of Biological Systems Engineering, Univ. of Wisconsin-Madison, 460 Henry Mall, Madison, WI 53706, United States. Electronic address: trunge@wisc.edu.
authors.forename: Troy
authors.initials: T
authors.lastname: Runge
mesh_terms: D005427:Flocculation; D008372:Manure / Q000382:microbiology*; D059027:Recycling; D012987:Soil
chemical_list: D008372:Manure; D012987:Soil
keywords: Centrifuge speed; Dairy manure; Liquid/solid separation; Pathogen indicator reduction; Polyacrylamide