In a semi-aerobic landfill where the inlet and outlet of a leachate collection pipe are opened to the atmosphere, when there are any driving forces, atmospheric air flows easily into the pipe. Therefore it will be expected that oxygen can penetrate from the pipe to interior of landfill due to difference of oxygen concentration.
The purpose of this study is to present calculation equations of air flow velocity in a single pipe, and to determine the pipe line design factors which are concerned with air flow in the pipe.
Main results are as follows :
1) Air velocity in a single pipe can be generated not only by a bit of temperature difference between atmosphere and landfill layer, but also surface wind of landfill site.
2) As a factor for leachate pipe design, temperature difference, wind velocity over surface of landfill site, and height of landfill layer have much more influence upon air flow velocity in the pipe than length and diameter of the pipe.
3) If a short length of the pipe is packed with crushed gravel, air flow velocity reduces drastically.
4) To make the aerobic zone wider in interior landfill layer, it is recommended that the inlet and outlet of pipe are opened to the atmosphere.

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Dynamic performance of paper resources in their lifecycles in Japan was evaluated by the previously presented mathematical model. Pulpwood resources, energy and cost, which are required for production and recycling of paper, paperwaste treatment, waste heat recovery and so on, were analysed to estimate the possible change from the present state in pulpwood consumption, in energy balance and in cost burden due to the promotion of wastepaper recycling.
The main results obtained under the limits considered can be summarized as follows: (1) The trade-off between energy (waste heat) recovery and mass (wastepaper) recovery is possible but has no practical role at present due to today's low waste heat recovery level. (2) The cost burden pattern between the paper production sector and the paperwaste treatment sector depends on the wastepaper price and its collection cost. (3) Introduction of cost sharing policies between two sectors may give economic incentives to promote wastepaper recycling.

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At general wastes incineration plants, there are problems regarding HCl in PVC, mainly Pb which is added to intensify the heat stability of PVC. Pb changes to fumes (ie. PbO) in incineration and is contained in fly ash. The maximum concentration of Pb amounted to 240 mg/l in the fly ash by the leaching test, but Pb was not detected in a leachate of the landfill buried in the fly ash. This paper describes adsorption and desorption of Pb in cover soil.
It was found that Pb²⁺was adsorbed according to the Freundlich formula, and the strength of adsorption was affected considerably by pH. Ca (OH) ₂which was added for removal of HCl increases pH at the leaching test to almost 12.4, so PbO liquefies as complex ion of Pb (OH) ₄^2-. In the landfill, Pb is adsorbed in cover soil at strong alkaline and physically according to a decrease of pH. Generally, pH of the leachate is almost neutral, so concentration of Pb was less than 0.005 mg/l. Author pointed out that it is possible for Pb to leach from the landfill if pH of the leachate changes extremely high or low.

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The conditions for enhancing the efficiency of an anaerobic digestion process were examined with waste activated sludge pretreated by ultrasonic disintegration, thermal treatments and freezing. The organic particulates in waste activated sludge were solubilized to soluble proteins and carbohydrates and other substances by various pretreatments. There is a clear correlation between the solubilization efficiency of waste activated sludge and the methane production. Ultrasonic pretreatment for 30 minutes resulted in a more than 60 percent increase in methane generation. The thermal pretreatment at a relatively low temperature can be expected to enhance the methane production with limited waste energy. In addition, the effects of the mixture ratios of waste activated sludge by various pretreatment and digested sludge on the anaerobic digestion process were also examined.

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