Abstract:In order to investigate the effect of mineral-based additives on organic matter degradation during composting of pig manure under aerobic condition, pig manure was mixed with corn stalk powder and the mixture was composted for 90 days after amending with mineral-based additives such as flyash, weathered brown coal, and bentonite at 2.5% addition amounts. And the organic matter degradation characteristics were evaluated by chemical analysis and FTIR methods. The results showed that the additives had no remarkable influence on composts temperature evolution. During the thermophilic phase, temperatures above 55℃ were rapidly established and continued over a week with the maximum temperatures up to 70℃ in all the composts. TOC and WSC decreased as composting progress, whereas the TOC decrease was enhanced in order of flyash, bentonite and weathered brown coal. Mineral additives improved the composts humification. Germination index of Ardisiasquamulosa presl- seeds showed a significant negative correlation with WSC, and presented significant positive correlations with PHA and DP. The organic matter of the pig manure-additive mixture was characterized by a high polymerisation degree of the humic-like substances, with a relative high proportion of humic acids in relation to fulvic acids. The FTIR analysis showed that the contents of the compounds with —OH,—CH3 and —CH2 groups decreased with time, while the contents of the compounds with —CO, —C—O—C,—COO and aromatic groups increased with time, and the organic matter degradation process could be last for 60 days during composting. The GI values increased with composting time, while the developments were significant inhibited during the initial stage when mineral-based additives were added. After 90 days composting GI values were over 0.5 indicating the maturity composts for all treatments.
