In this paper, we discuss the main economical barriers in implementing resource recovery systems of solid waste within the market.
Generally speaking, there are two types of barriers technical and economical. Economical, especially, institutional barriers may be more essential than the technical ones judging from the fact that the present structure of industries is fitted to the use of virgin raw and not recoverd materials.
The economic success of a recovery system depends on continuing and stable revenues derived from selling the products made from recoverd materials. Marketing barriers are related not only to the cost of the products but also the other problems hidden behind the market price. We make these hidden problems clear by showing many practical examples and by clustering these problems into two groups:
(A) barriers related to the competition principle of the market structure, and
(B) barriers related to the characteristic of solid waste.
As a result, it is shown that both nonmarket mechanical means and reformation of the current economic structure are necessary in order to comprehensively promote the resource recovery.

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Wast water discharged in the production process of Japanese cake, ice cream, and potato chips were treated first with the one stage Rotating Biological Contactor and then with series of the three stage Rotating Biological Contactor and the two stage activated sludge process.
Wast water of 1200 mg BOD /1 were treated with the Rotating Biological Contactor system- Activated Sludge Process system at the rate of 300 m³/d, and the experimental results showed that the wast water could be purified to the 4-10 mg /1 level without dilution.

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The behaviors of N₂O, NO and NH₃ in N₂O-NH₃-N₂ and NO-NH₃-N₂ mixture under the UV irradiation were studied at room temprature. The decomposition rate of NH₃ in NH₃-N₂ mixture under the UV irradiation was proportional to the concentration of NH₃, and the rate under a low pressure mercury lamp irradiation was three times larger than that under a high pressure mercury lamp irradiation. No effect of NH₃ and N₂O was observed on the decomposition rate of N₂O and NH₃ under the irradiation with a low pressure mercury lamp. While N₂O did not change and NH₃ decomposed slowly by the irradiation with a high pressure mercury lamp, and the rate was not affected by N₂O.
NO and NH₃ in NO-NH₃-N₂ mixture decomposed rapidly with the formation of small amount of N₂O as a by-product under a low pressure mercury lamp irradiation. The amount of NO decomposed was nearly equal to that of NH₃, the rate of decomposition of NH₃ increased with the increase of the concentration of NO, and was expressed by the following equation:
d [NH₃] /dθ=k₁ [NH₃] +k₂ [NH₃] [NO] ^1/2 [θ; W/F (watt⋅min⋅l^-1) ]
The decomposition rate of NO in NO-NH₃-N₂ mixture under a low pressure mercury lamp irradiation was nearly equal to the decomposition rate of NH₃, and was ten times larger than that under a high pressure mercury lamp irradiation. The yield of N₂O (less than 10% of the amount of NO decomposed) increased proportionally to the amount of NH₃ decomposed and the concentration of NO.

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