A theoretical method is presented for numerical calculation of air flow in the leachate collection pipe network in semi-aerobic landfills. It is shown that the presented method is also effective on a complex network. The method is applied to an assumed typical landfill site and the following are obtained. 1) Maximum air temperature increase between inlet and outlet in the pipe network is a good index for comprehensively estimating the influence of thermal factors such as atmospheric temperature, temperature of pipe wall and heat transfer coefficient between the pipe wall and air in pipe. 2) The depth of the landfill has little effect on the inlet velocity of air flow. 3) The maximum of the inlet air flow rate is attained when the diameter of the main pipe is more than 1 m and enough air cannot be supplied into a leachate collection pipe network when the diameter is less than 0.4 m. 4) The less diameter of branch pipe there is, the less velocity of inlet air flow is attained. Enough air cannot be supplied when the branch diameter is less than 0.15 m. 5) Enough air can be supplied even if the distance between each branch pipe is 50 m.

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In this paper, techniques for processing industrial waste by arc plasma which generates among six carbon electrodes using a six-phase current power supply and its applications are described. The power supply of this system can be realized by the combination of three single-phase transformers with the center-taped secondary coil. The characteristics of arc plasma generated around the discharge electrodes and a few examples applying an arc plasma to industries are presented here. The major advantages of this system are as follows:
(1) As arc plasma always exists in the discharged space, the stable discharge phenomena can be maintained in low voltage,
(2) Arc plasma at high temperature can be obtained in a wide space.
By the use of this system, incinerated urban garbage can be slagged, and a lot of spherical ceramics of about 200 microns in diameter are obtained from ash generated by the operation of power plants.

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Twelve different kinds of excess sludge produced at wastewater treatment systems in the food manufacturing industries not only include rich nutrients but scarcely ever contain any toxic matters. Thus it is expected that those excess sludge can be employed as nutrients for cultivating edible mushrooms in the same way as food industrial wastes such as rice bran, wheat bran, etc..
In this study, edible mushrooms were cultivated in a media containing excess sludge as a nutrient. The hypha growth and fruit body yield were examined in order to reduce and reuse excess sludge. From the view point of hypha growth, it was found out that some of the media containing excess sludge from miso, soy sauce, fish paste, red bean paste were superior to the existing other excess sludge for edible mushrooms. As a result of the cultivation test, moreover, it was proved that some media, where the excess sludge had been added to sawdust, caused an increase in the fruit body yield compared with general media containing sawdust with rice bran. Accordingly, it is concluded that some of the excess sludge which was produced in the food manufacturing industries was usable as a nutrient in the cultivation for mushrooms so long as the category of the manufacturer releasing the excess sludge and the variety of the mushroom were properly selected.

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The gas flow pattern is experimentally visualized in the combustion chamber of a municipal solid waste (MSW) incinerator. The Tracer method with soap bubbles is applied to the cold transparent model of the chamber and paths of many soap bubbles are recorded by a video recorder.
Path line diagrams, mixing index and velocity vector diagrams are produced by processing and analyzing video data. The path line diagram is useful to understand visually gas flow behavior in the chamber. The velocity vector diagram shows clearly the eddy area and gas flow change by overfire air jet. The mixing index, which is defined by overlap of path lines, evaluates the relative effects of the overfire air jet based on the number of nozzles, location of the nozzles and the air flow rate.
Experimental data of the path line and velocity vector make it possible to evaluate the effectiveness of computer simulation of the gas flow pattern in the chamber.

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This study presents a numerical method for calculating gas flow around a sanitary landfill gas vent, when gas flows by pressure. The method described is a three-dimensional compartmental model and includes methods to determine the dimensions for the model. Using the numerical method, the following results are obtained.
1) In the case of gas generation rate (G [s^-1] ) × depth of refuse layer (L_z [m] ) ≤leakage gas flux through final cover soil, q_c obtained from Eq. (9), a landfill-gas vent such as that studied in this paper is ineffective.
2) It is pointed out that the landfill-gas vent should be designed by fitting both the landfill gas collection efficiency (η) and the maximum pressure under final cover soil (ΔP_max) .
3) Non-dimensional differential pressure ΔP_max, which is defined as ΔP_max/ΔP, and η can be mainly estimated using two parameters (K_s/K_x, L_x/L_z), where L_x=half of distance between two vents, K_x=horizontal permeability of refuse layer, K_z=vertical permeability of refuse layer, and K_s=permeability of final cover soil, ΔP=μG (L_z) ²/K_x, μ=viscosity [Pa·s] .
4) η and ΔP_maxare not influenced by the intermediate soil layers and horizontal daily cover soil layers.
5) Vertical daily cover soil layers strongly influence η and ΔP_max. Therefore soil with high permeability should be used for daily cover soil.
6) When a gas vent is used for collection of both leachate and gas, both 1-η and ΔP_maxdecrease by 80% compared with the case that the gas vent used only for gas collection.

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Previously, we reported a new method for producing activated carbon from sewage sludge for the purpose of sludge utilization and minimization.
Herein, we studied whether the improvement of KOH-HCl treatment was suitable for various kinds of organic sludge, and how to treat waste water generated from the process of activated carbon production.
The activated carbons, which were made from various kinds of organic waste sludge such as sewage sludge, sludge from a GAPPEI SYORI JOHKASOU, sludge from a night soil septic tank, sludge from a synthetic fiber factory and sludge from a dairy factory, had 140-350ml/g for the methylene blue adsorption and 460-1, 771 m²/g for the specific surface area. The waste water after KOH-HCl treatment contained various heavy metals, which were removed by the neutralizing coagulation treatment. The quality of the treated waste water showed values under the effluent standard. The yield of activated carbons obtained from dry sludge ranged from 8% to 19%.

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