NRCS Solid-Liquid Separation Document – It is Finally Here!!

NRCS has a new technical document entitled “Solid-Liquid Separation Alternatives for Manure Handling and Treatment.”  It was created through efforts from Dr. John Chastain, Clemson University with funding provided by USDA-NRCS.

Screw press solid-liquid separator
Screw press solid-liquid separator (Source: USDA-NRCS)

This document brings together both the theory behind solid-liquid separation and the practical application of many different separation technologies.  Several farm scale demonstration projects are also summarized in the report. Solid-liquid separation can serve to achieve many livestock operational objectives such as nutrient partitioning, improved pumping characteristics, solids removal from storage facilities and reduced organic loadings.  The use of separation technologies is essential for many operations and has become an integral part of the efficient performance of these livestock facilities. Some of the purposes and uses of this document include assisting in solid-liquid separation technology selection, evaluating separation performance, and quantifying the impact of solid-liquid separation on manure management.  This presentation provides an overview of this document including methods of solid-liquid separation, influence of manure characteristics and handling methods, fundamentals of solid-liquid separation, performance of various solid-liquid separation technologies, unique separation technologies and applications and design considerations.

What Did We Do?

Use of coagulant and flocculant to enhance solid-liquid separation
Use of coagulant and flocculant to enhance solid-liquid separation (Source: USDA-NRCS)

Extensive effort through literature searches and testing went into compiling performance and design information on various types of solid-liquid separation technologies.  Separation theory was incorporated into the document to provide an understanding of separation principles and background information to assist in technology selection for improved system performance.  To improve usability of the document, it was divided into the following chapters: Methods of Solid-Liquid Separation, Manure Characteristics and Handling Methods, Fundamentals of Solid-Liquid Separation, Measures of Solid-Liquid Separation Performance, High-Rate Solid-Liquid Separation, Unique Applications of Solid-Liquid Separation Technology, and Design Considerations.  Several examples were provided throughout to assist in the design process of the various technologies. The document also includes information on the uses and benefits of coagulants and flocculants and separation methods associated with sand laden manure. Numerous system diagrams assist in illustrating the vast array of solid-liquid separation technologies that can be implemented in an animal manure treatment system.

What Have We Learned?

Sand settling land
Sand settling land (Source: USDA-NRCS)

This work brings together fundamental information about solid-liquid separation, benefits and limitations of many separation technologies, performance measurement techniques along with design considerations into one document.  Even though there are significant differences in performance and costs between the various separation technologies, the approach selected is largely dependent on critical elements such as landowner objectives, facility size, performance goals, operation and maintenance and other factors.  This document will help designers and operators choose the separation technology or technologies that will best meet the goals established for the operation.

Future Plans

This document will be published as chapter 4 of the USDA-NRCS National Engineering Handbook, Part 637 Environmental Engineering.


Jeffrey P. Porter, P.E.

Animal Manure and Nutrient Management Team Leader

USDA-Natural Resources Conservation Service

Additional information

Once published, a copy of the document can be found at


A special thank you goes out to the Piedmont-South Atlantic Coast Cooperative Ecosystems Studies Unit (CESU).  This Cooperative and Joint Venture Agreement allowed for this work to be completed.

Additional support was provided by the Confined Animal Manure Managers Program, Clemson Extension, Clemson University, Clemson, SC.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.