Composting Methods for Pig Sludge and the Stabilized Investigation of Crop Cultivation
2009
Oh, T.S., Kongju National University, Yesan, Republic of Korea | Kim, C.H., Kongju National University, Yesan, Republic of Korea
This study was carried out development a new composting system to lower copper and zinc concentration in pig sludge compost and conduct an inquiry into the possibility of crop cultivation. The concentrations of nitrogen, phosphorus and pH averaged 4.4%, 6.3% and 7.57, respectively, which were higher concentrations than in commercial organic fertilizers, and the concentrations of copper and zinc averaged 805 and 1,704 mg/kg, respectively, which were beyond the heavy metal concentration limit in byproduct compost. Hydrated citric acid Ⅰ lowered the concentrations of copper and zinc by 58% and 97%, respectively and hydrated oxalic acid Ⅱ lowered the concentrations of copper and zinc by 48% and 56%, respectively in pig sludge compost. Lower concentrations of copper and zinc in pig sludge resulted from the enhanced hydrated-citric acid concentration in organic acid solution mixed with distilled water. The concentrations of copper and zinc were 330, and 41 mg/kg in the pig sludge treated with 100% hydrated citric acid. Agitation composting system stabilized the compost earlier than the stationary composting system, in which the stabilization condition was confirmed by higher temperature by 4℃ at highest temperature and 7 days earlier cooling down after highest temperature. The levels of germination index (G.I) 80 were obtained 15 and 20 days after composting in agitation and stationary composting system, respectively. The concentrations of copper and zinc were 2.4 and 4.26 mg/kg respectively in soils amended with pig sludge compost after removing process of heavy metals by citric acid, but 8.0 and 22.37 mg/kg, respectively in soils amended with Pig Sludge. The concentrations of heavy metals was highest in corn cultivated in soils amended with pig sludge. The copper and zinc concentrations in corn leaves were 75.2 and 50.56 mg/kg respectively, which were 4 and 2 fold higher than the corn cultivated in soils amended with pig sludge compost after heavy metal removing process by hydrated citric acid.
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