The silver deposits were examined in the three silver collection methods from the waste fixing solution of X-ray photograph, hydrogen peroxide method, electrolytic method and copper plate immersion
The deposit was identified as silver sulfide in the former two methods, but as mixture of silver and copper oxide (I) in the last method. Pure silver could not be obtained by the direct hydrogenation of silver sulfide, but it was obtained by a low temperature (400°C) of silver chloride, which had been obtained by a nitric acid treatment followed by a sodium chloride treatment.
The immersion method using copper plate was economical, but the silver was contaminated wiht the metal.

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The regional waste treatment planning is needed in many areas where it is difficult to treat wastes effectively and economically, and to find suitable disposal sites by themselves. This planning in which several municipalities cooperate with each other to treat their wastes, is a good solution for regions.
At this moment, it is the problem how to decide the boundary of planning area. There are so many evaluation factors ; historical, geographical, social, economical, and political factors, in deciding the size of area-wide, however it is difficult to consider all of them.
We propose a method to evaluate the distance between each area, and to make a cluster according to the length, that is, the two closest areas are connected at first. Then all areas are connected with each other in turn by the length of two areas. And we show in a case study, how to decide the most economical boundary of planning area by evaluating treatment and transport costs.

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