NOVELTY - System comprises a drum screen (10) for separating pig liquid fertilizer into solid and filtrate, a settling tank (30) for separating filtrate obtained from the drum screen into supernatant and precipitated solution, an anaerobic digestion tank for producing liquid fertilizer by anaerobic fermentation, an aerobic liquid fertilizer tank for producing liquid fertilizer by aerobic fermentation, and a sealed cylindrical fermentation tank for producing compost by fermenting through supplying solid contents separated from the drum screen.    USE - The system is useful for producing high-quality liquid fertilizer (claimed).    ADVANTAGE - The system increases hydrolysis efficiency, and prevents excessive temperature rise of the aerobic liquid fertilizer tank.    DETAILED DESCRIPTION - System comprises a drum screen (10) for separating pig liquid fertilizer into solid and filtrate, a settling tank (30) for separating filtrate obtained from the drum screen into supernatant and precipitated solution, an anaerobic digestion tank for producing liquid fertilizer by anaerobic fermentation through supplying the precipitated solution separated from the sedimentation tank, an aerobic liquid fertilizer tank for producing liquid fertilizer by aerobic fermentation through supplying the supernatant separated from the sedimentation tank, and a sealed cylindrical fermentation tank for producing compost by fermenting through supplying the solid contents separated from the drum screen. The low-concentration liquid fertilizer of the aerobic liquid fertilizer tank contains large amount of organic matter. The aerobic liquid fertilizer tank comprises a mixing tank for optionally mixing the compost obtained from the sealed cylindrical fermentation tank, aerobic liquid fertilizer obtained from the aerobic liquid fertilizer tank and anaerobic liquid fertilizer obtained from the anaerobic digestion tank. The filtrate of the drum screen is separated into supernatant and precipitated solution which is spent in a precipitate separating tank (20). The precipitated solution is subjected to secondary solid-liquid separation to obtain the filtrate and solid content which are introduced into a high speed centrifuge (25). The solid content is introduced into the sealed cylindrical fermentation tank. The filtrate is introduced into the settling tank.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the system (Drawing includes non-English language text).    Drum screen (10)    Precipitate separating tank (20)    Centrifuge (25)    Settling tank (30)    Hydrolysis tank (40)