Ayako Tachifuji-Tanaka*, Yasushi Matsufuji* and Masataka Hanashima*

*Department of Civil Engineering, Faculty of Engineering, Fukuoka University

+ Correspondence should be addressed to Ayako Tachifuji-Tanaka:
(8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-80 Japan)

Abstract

Recently, with the rapid progress of the incineration technique, the landfill volume of incineration residues is increasing. Therefore, the salinity of leachate from landfill sites is increasing. On the effect of the high salinity of the landfill layer, we investigated the microbial degradation of solid wastes using the small-scaled lysimeters. The biodegradation of solid wastes and the purification of leachate were retarded under the high salinity condition. But it did not show up clearly because narrow pores like soil aggregates existed in the landfill layer. Also, the bacteria flora of leachate succeeded to the flora, in which the halophilic bacteria dominated, with the increase in the concentration of chloride in leachate. As a result, the numberofNBorganismshardlydecreased.Ontheotherhand,theenzymeactivitiesforbio-degradation of organic compounds in leachate declined and the growth of the organisms which participated in the nitrogen compounds catabolism were inhibited, especially on the denitrification. Consequently, the concentration of inorganic nitrogen compounds in leachate decreased less than that of organic carbon compounds under the high salinity of the landfill layer.

Key words: landfill, biodegradation of solid waste, high salinity, leachate, landfill layer