Application of Gel Chromatography to Monitor the Decomposition Process of Sewage Sludge in Soil

Abstract

The decomposition process of sewage sludge applied into soil was followed by gel chromatography of the water extract from the soil-sludge mixture. The extract was loaded to the column packed with Sephadex G-15 and eluted by 0.1M NH4OH and continuously detected by UV absorption at 280 run. The seedling tests of komatsuna (Brassica campestris L. var. rapiferafroug) were carried out on the same soil-sludge mixture. The transition of the gel chromatographic patterns; I, II, and III, which were characterized by special peaks in each chromatogram, was observed during the sludge decomposition in soil. It was estimated that pattern III corresponded to the stable stage, in which the decomposition of easily decomposable components in the sludge was almost complete, as no more change was detected in the gel chromatogram. In each stage of the decomposition, which is shown by the respective gel chromatographiC patterns, the degree of seedling growth inhibition was correlated with the intensities of the characteristic peaks of the gel chromatograms. Gel chromatography of the water extract from soil-sludge mixture is proposed as an effective method to monitor the decomposition process of sewage sludge applied to soil.