Changes in characteristics of composting factors according to the presence or absence of air in pig manure compost and correlation between each factor

The composting process of pig manure requires manure separation from the slurry and maturity under aerobic conditions. Thus, we investigated the anoxic manure characteristics and the correlation between each composting factor. First, a decanter solidliquid manure separator was used, and the separated manure was transported to the laboratory in an impervious bag. We mixed manure and sawdust (bulking agent) in a 6:4(V/V) ratio to adjust the moisture content to 70%. About 140 liters of mixed composting materials were treated in cylindrical composting reactors with a bottom diffuser. Three composting reactors were installed inside a laboratory to reduce the ambient temperature, where the room temperature was 25C continuously. Supplied air volume to the composting reactor was 100LPM/ 1 m 3 of compost. The composting test reactors had a connected air supply system, but the control reactor had none. pH and EC of the raw manure were 8.42 and 2,341/, and the pH and EC of sawdust were 5.01 and 149/, respectively. Mixed material showed pH and EC of 8.48 and 2,060 s/cm, respectively. After two days of composting, the pH of the compost pile in test reactors and control increased to 9.08, 9.08, 9.13, and 8.57, respectively, and were stable for 20 days. The change in NH 4 -N had a similar tendency with pH and had a 0.84 correlation coefficient, but for EC and Salt, the correlation was 0.98. between VS/TS and NH 4 -N was 0.83. However, VS/TS had a negative correlation of -0.64 with ripeness, -0.57 with T-N, and -0.79 with T-P.