The comparison study of compost and natural organic matter samples.

Sewage sludge is a serious problem facing modern wastewater treatment plants. One of the methods to safely utilize the sludge is through composting and the agricultural use of the final product. In this study the compost samples from municipal sewage sludge are compared to the natural, rich in organic matter samples. Based on physicochemical properties of the material, the maturity indices are obtained to evaluate the quality of organic matter and estimate the similarities between the samples. The study shows that one-dimensional analysis like that based on maturity indices does not provide satisfactory answers concerning the nature of such complex materials. The data set of the analysis naturally possesses a multidimensional character so that the employment of advanced chemometric techniques like cluster analysis show a number of features which were hidden within the 'data flood'. The major conclusion of this work is that the compost from sewage sludge is similar to peat in the significance of the properties of the organic matter. Moreover, the organic matter of agricultural soil, which is most stable and has been naturally matured over a long period of time, differs substantially from the other samples.