STEADY-STATE MESOPHILIC DESIGN EQUATIONS FOR METHANE PRODUCTION FROM LIVESTOCK WASTES

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ABSTRACT Methane production from animal waste has received considerable research attention in the previous ten years. This attention was due mainly to the energy shortage experienced during the mid and late 1970s which caused severe hardship in animal agriculture, particularly in the swine and poultry production industries. Research on the commercial potential of methane production from animal wastes began with emphasis on beef feedlot and caged layer wastes, with swine and dairy waste studies following later. The research proceeded from initial investigations of feasibility through stages involving reactor hardware and finally into development of mathematical prediction models requiring computers. As the data base was developed using the early studies, the mathematical models were made more accurate and validated with a larger data base. The state-of-the-art of system design today is such that a computer is required to obtain accurate predictions of methane production. Computers are often not convenient for field use or for use in classrooms, and the need for simple design equations that can be used with hand-held calculators for quick and accurate estimation is great. This manuscript describes the development of a set of simple, fast, and accurate methane production equations for the major animal species of swine, beef, dairy, and poultry. The latest, most comprehensive validated computer model of methanogenesis of animal waste was used to provide a data base for the development of these simple predictive equations. The equations provide prediction confidence of 97% or greater based on correlation of predicted data verses the data obtained using the computer model.