抄録
There are some hazardous substances in useful industrial materials that are poisonous to human health, environment, or other materials. Such substances can be generated in any stage of social material circulation such as production, product use, and waste treatment. Therefore, we must introduce a process that eliminates such hazardous materials from the social material circulation system. We have studied the effects of the factors of the recycling ratio (r) and removal ratio (s) on the accumulated amount of hazardous materials (Q), in particular on six heavy metals: Cd, Pb, Cr (VI), As, Hg and Se, where Q is described as the summation of the Hg t-toxic equivalent quantity of the six heavy metals. In a complete recycling society (where r = 1.0), the Q becomes 5,000 times more than the allowance level in spite of a high removal effort (s = 0.9). Even under the condition of a rather low recycling level (r = 0.4), we must remove more than 99.99 % of the hazardous materials to satisfy the allowance level of the environmental standard of Hg. Consequently, we have pointed out some problems in establishing a recycle-based society from the viewpoint of the elimination of poisons. As a case study, we discussed if an ultimate elimination could be theoretically achieved in a high performance elimination process in which the temperature, the partial pressures of O2 and Cl2 are controlled.
