solid-liquid separation – Livestock and Poultry Environmental Learning Community

April 30, 2019October 22, 2019

Characterization of Nutrients and GHG Emissions from Separated Dairy Manure

This study has the objectives of characterizing dairy manure pre and post solid-liquid separation (SLS), estimating and comparing processing efficiencies between different technologies, and relating emissions to manure characteristics by using modeling tools.

What did we do?

Manure samples from nine dairy farms in southern and eastern Wisconsin were collected every two weeks. All nine farms separated manure into liquid and solid streams and seven farms used anaerobic digesters (ADs) prior to solids separation (Table 1). For all farms, manure was sampled pre-processing (untreated manure) and after any individual processing step in order to isolate the performance of each treatment unit at each farm (Figure 1). All manure samples were analyzed for total solids (TS), volatile solids (VS), total nitrogen (TN), ammonia (NH₃), total phosphorus (TP), total potassium (TK) and chemical oxygen demand (COD). Separation efficiency was estimated by solving a system of two equations of separation mass balance (Equations 1 and 2) based on the concentrations of each constituent.

Where:

- - - X (kg) is the constituent under evaluation (e.g. TS, NH₃, etc.)
    - [ ] indicates percent concentration in the solid (solid, out), liquid (liquid, out) fractions after separation, and total before separation (total, in)
    - Manure (kg) is the manure mass in the solid (solid, out), liquid (liquid, out) fractions after separation, and total before separation (total, in)

What have we learned?

Both screw press and centrifuge technologies achieve higher separation efficiencies for TS and VS than for TN, NH₃, TP, and TK, meaning that more TS and VS stay with the solids fraction. Moreover, NH₃ stays almost entirely in the liquid fraction. Results indicate that centrifugation might achieve higher TP separation efficiencies than screw pressing. Greenhouse gas (GHG) emissions, were affected by the management practices used to handle the liquid and solid fractions. Methane emissions from liquid storage are reduced as a percentage of the VS stays with the solids fraction. However, nitrous oxide emissions from the separated solids might increase if separated solids are stored and not quickly land applied or transported outside of the farm for posterior use.

Future Plans

Analysis for anaerobic digestion efficiency and pathogen inactivation will be incorporated in this study to conduct a complete assessment of manure characteristics after AD and SLS and their impact on different environmental indicators.

Table 1. Summary of each farm’s manure management process.
Farm ID	AD	SLS	Feedstock
1	Mixed plug flow	Screw press	Dairy manure
2	No	ABRU	Dairy manure
3	Complete Mix	Screw press with blower	Dairy manure
4	Mixed plug flow	Screw press	Dairy manure
5	Mixed plug flow	Screw press	Paunch manure, food waste
6	Mixed plug flow	Screw press	Dairy manure
7	Mixed plug flow	Screw press	Dairy manure
8	Complete Mix	Centrifuge	Dairy manure, ethanol byproduct, FOG
9	No	ABRU	Dairy manure
AD: anaerobic digestion, SLS: solid-liquid separation, ABRU: aerobic bedding recovery unit , FOG: fat, oil, and grease

Figure 1. Scheme of the manure processing technologies and sampling locations.

Authors

Aguirre-Villegas Horacio Andres. Assistant Scientist. Department of Biological Systems Engineering, University of Wisconsin-Madison. aguirreville@wisc.edu

Sharara Mahmoud. Assistant Professor. Department of Biological and Agricultural Engineering. NC State University

Larson Rebecca. Associate Professor. Department of Biological Systems Engineering, University of Wisconsin-Madison

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.

April 4, 2019October 22, 2019

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 (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 (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?

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.

Author

Jeffrey P. Porter, P.E.

Animal Manure and Nutrient Management Team Leader

USDA-Natural Resources Conservation Service

jeffrey.porter@gnb.usda.gov

Additional information

Once published, a copy of the document can be found at https://directives.sc.egov.usda.gov/.

Acknowledgements

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.

March 5, 2019March 28, 2019

Overview of Solid-Liquid Separation Alternatives for Manure Handling and Treatment Document

Waste to Worth home | More proceedings….

Is Solid-Liquid Manure Separation Worthwhile?

* Presentation slides are available at the bottom of the page.

Solid-liquid separation of animal manures and other agricultural products can be an integral part of a livestock operation ranging from improved facility performance to enhanced nutrient management. A document entitled “Solid-Liquid Separation Alternatives for Manure Handling and Treatment” is being created through work by Clemson University and funding from USDA-Natural Resources Conservation Service. The purpose of this document is to assist in solid-liquid separation technology selection, evaluation of separation performance, and quantifying the impact of solid-liquid separation on manure management. This presentation will provide an outline 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, separation enhancement methods, and design considerations. An overview of various farm scale separation technologies is also presented in the solid-liquid separation document.

What Did We Do?

Geobag used with metal salt and polymer to separate solids and nutrient partitioning of swine manure

In this document we have provided a detailed compilation of empirical, theoretical, and practical information related to the performance and design of solid-liquid separation systems for animal manure treatment. The information is divided into the following chapters: Methods of Solid-Liquid Separation, 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. Within these chapters detailed information is provided on: the influence of entrainment on the performance of mechanical separators, design of gravity settling using discrete particle settling and hindered settling theory, efficacy of combining separator methods in a single machine, benefits of using coagulants and flocculants, benefits of solid-liquid separation, and a summary of the solid-liquid separation methods that have been used with sand-laden dairy manure. The publication also provides twenty-one detailed examples such as: design of settling basins based on hindered settling velocities, calculation of the performance of a variety separator options using field data, calculation of dimensions for sand lanes, determination of chemical need to enhance mechanical solid-liquid separation, and sizing of storages for separated solids. Numerous system design diagrams are also provided to demonstrate the wide variety of ways that solid-liquid separation can be implemented into an animal manure treatment system.

What Have We Learned?

Sand settling lane for flush dairy operation

Future Plans

This document will be published as a USDA-NRCS technical note or as part of the National Engineering Handbook, Part 651 Agricultural Waste Management Field Handbook.

Authors

Jeffrey P. Porter, P.E. Environmental Engineer Manure Management Team USDA-Natural Resources Conservation Service; e-mail – Jeffrey.Porter@gnb.usda.gov

Dr. John P. Chastain, Professor and Extension Agricultural Engineer School of Agricultural, Forestry, and Environmental Sciences Clemson University; email – jchstn@clemson.edu

Additional Information

Screw presses used on a dairy farm following anaerobic digestion

John Perkins Chastain, PhD Homepage

East National Technology Support Center Directory

NRCS on Livestock

Solid Separation Technologies for Animal Manure Webinar

Acknowledgements

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 take place.

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. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

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