In this study the effects of temperature, fermentation type and hydraulic retention time were investigated to optimize biogas yield and minimize production costs under lab scale for batch anaerobic digestion of goat manure. The growth and activity of anaerobic microorganisms is influenced by some parameters like temperature, moisture content, pHvalue and volatile fatty acids (VFA), which were measured before the study. The methane values were between (61.89 -69.35%). A cost equation was

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... ed to calculate the total biogas cost LE/liter at different conditions. The minimum biogas production cost was 4.09 LE/liter at the highest cumulative production of 128.74 liter at temperature of 60 °C for dry fermentation.