On the basis of the typical water contents in Table 2, the organic fractions in Table 1 and chemical components in Table 3, the individual chemical component proportion in the fresh MSW is the sum of chemical component proportion in each organic fraction:
equation(1)
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where mj is the wet proportion of individual chemical components in MSW (%), j is the number of chemical components, Mi is the wet proportion of individual physical compositions in MSW (%), i is the number of physical compositions, Wi is the water content of individual physical compositions (%), and ξi is the dry proportion of individual chemical components in each physical composition (%).
Fig. 1 shows the proportions of chemical components of fresh HKWC and LKWC MSWs by the same wet basis. The total average proportion of rapidly degradable components in fresh HKWC MSWs is 18.6%, higher than the average value in fresh LKWC MSWs, which is 15.35%. As a rapidly degradable component, sugar is the main substance in fresh HKWC MSW. The average proportion reaches 9.92% in fresh HKWC MSW, but is only 2.16% in fresh LKWC MSW. By contrast, the proportion of fast cellulose in fresh LKWC MSW is as high as 12.83%, higher than that in HKWC MSW, which is 7.03%. Compared with sugar, for which the primary metabolite is acetic acid during the hydrolysis and acidification stages, the anaerobic degradation of cellulose is more complex and slower. The anaerobic degradation processes in HKWC and LKWC MSWs are influenced by the proportion and degradation characteristic of each chemical component. Rapid accumulation of organic acid may be thus induced in the HKWC MSW landfill.