MANURE MANAGEMENT
P1H-62
pork industry handbook
PURDUE UNIVERSITY • COOPERATIVE EXTENSION SERVICE • WEST LAFAYETTE, INDIANA
Lagoon Management
Authors
Lawson M. Safley, Jr., North Carolina State University
Charles D. Fulhage, University of Missouri
Raymond L. Huhnke, Oklahoma State University
Don D. Jones, Purdue University
Reviewers
Glenn A. Church, II, Iowa State University
Albert J. Heber, Purdue University
James A. Moore, Oregon State University
Ronald E. Hermanson, Washington State University
Introduction
A lagoon is a basin, typically earthen, used to treat and store manure from pork production facilities. A lagoon appears similar to an earthen liquid manure storage; however, it serves the added function of dilution and treatment. The difference is in the length of storage, in the amount of dilution added, and in the fact that a lagoon is never completely emptied. Lagoons are used extensively in the United States. They rely on bacteria to stabilize organic material. Most lagoons used in the swine industry are either anaerobic (bacteria existing in the absence of oxygen) or facultative (combination of anaerobic and aerobic bacteria) treatment units. However, in lagoons considered to be facultative, free oxygen is rarely found below the top few inches of liquid. Aerobic lagoons (bacteria requiring oxygen) also can be used to treat swine manure. However, some means of mechanically supplying the oxygen is typically required.

The lagoon can be used in a variety of manure treatment systems. Properly designed and managed lagoons have a number of attractive features:
•	stabilization and reduction of organic matter
•	reduction in concentration for some nutrients
•	adaptability to a wide range of climatic and topographical situations
•	compatibility with liquid manure handling and or collection systems
•	reasonable capital and operating costs
•	reasonable management requirements
•	infrequent sludge removal
•	somewhat tolerant of shock loading.
Lagoons are especially compatible with hydraulic flush manure removal and pit recharge systems. Many pork production systems recycle lagoon effluent as the flush or pit recharge liquid.
Before selecting or finding a location for a lagoon, the entire manure management system (manure collection and transport, lagoon, land application equipment, crops and land to receive lagoon nutrients) should be planned and evaluated. If any of the elements do not support the complete design, either an alternative site or an alternative manure management system should be considered.

Lagoon Design
Lagoon Design Standards
Lagoons treat manure biologically with several types of bacteria working together to decompose organic material. The rate of bacterial decomposition is governed by lagoon temperature. The long-term rate of manure addition to a lagoon should not exceed the rate at which stabilization can occur. The rate that lagoons can reasonably treat manure is termed loading rate. Loading rate can be defined as the amount of manure that will be added per volume of lagoon per day.

Lagoons must be designed to meet a predetermined loading rate criteria. The loading rate for anaerobic lagoons can be expressed as 1) pounds of volatile solids per cubic foot of lagoon volume per day, 2) pounds of chemical oxygen demand (COD) per cubic foot of lagoon volume per day or 3) pounds of live animal weight per cubic foot of lagoon. Anaerobic lagoon loading rates vary throughout the United States as a function of mean annual air temperature. As temperature increases, loading rates can increase because the bacteria are more active and can treat larger quantities of manure. This defines the minimum design volume for an anaerobic lagoon. A final anaerobic lagoon design must include this volume plus additional volume to store manure, accumulated sludge, precipitation and lot runoff for desired amounts of time.