Change in microbial numbers during experimental composting has been investigated. The results show that bacteria and actinomycetes play an important role in decomposing the composting material. The number of bacteria has no relation to the efficiency of composting, though it greatly correlates to the decomposition ratio. Bacterial growth activity that shows potential of bacterial growth was originally proposed. The influence of pH and the decomposition ratio on the growth activity has been studied. It was clarified that the bacterial growth activity is useful in evaluating the efficiency of composting and the maturity of produced compost.

View full abstract

[in Japanese]

View full abstract

Behaviors of pollutants, in particular organic carbon and nitrogen, in solid waste landfill layers and the factors affecting their decomposition, have been studied under semi-aerobic condition using four large scale simulated lysimeters of different packed thickness. This paper presents about 800 days of data through November 1991.
Data in this study indicated that the thicker solid waste layers showed less leaching rates in amounts of TOC and T-N. If the layer, however, became as thick as 8 m, no significant decrease in the leaching rate of T-N was observed. This is because nitrogen leached out in the form of NO₃^--N without smoothly denitrifying at the bottom of the landfill layer. By this, it was suggested that temperature and pH in the landfill layer play important roles not only in microbial activities, but also in dissolutions of organic carbon and nitrogen. Consequently, dissolution and microbial degradation in the landfill layer, resulting from the changes in temperature and pH, tend to occur in turn when leachate moves through the layer vertically. Such behaviors lead to shaping distinctive TOC and T-N concentration distributions.

View full abstract

There are many kinds mutagenic of chemicals found in the fly ash that comes from municipal incinerators.
In this study, the solvent extraction method was investigated for the Ames mutagenicity test of fly ash.Tested solvents were hexane, ethyl acetate, aceton, ethanol, dimethylsulfoxide (DMSO), methanol and distilled water.
Higher extraction efficiencies of the mutagenic substances were obtained by DMSO for most of the fly ash samples, and DMSO could be used directly in the Ames test. The mutagenic substances could be recovered almost completely using 2 times the extraction for 10 minutes with 6ml of DMSO per 1g of fly ash.
Consequently, the extraction method shown in Fig.10 is recommended for the Ames mutagenicity test of fly ash from incinerators. Higher mutagenicity was observed in the tests using S9 mix by this extraction method.

View full abstract