The superheated steam has used in the field of food engineering when it has the remarkable character such as the operation in the ordinary pressure, the good efficiency for heat transfer and the treatment in the steam without oxygen. It must be applied for the recycling process to recover the metal and remove the impurity. The examples were introduced to apply the technology for the removal of oil attached to the magnesium cutting powder and the treatment of metal plated resin with painting. We succeeded to remove less than 0.1% of oil for magnesium cutting powder. It was a value enough to bring it to the reconstructive process. The painting was damaged for the metal plated resin to recover the nickel and copper in the plating dissolution process. The both were promising results of the research and development for industrial-government-academic complex in north Kyushu district.
In the present study, generation of iodine by an electrolytic oxidation from solutions containing iodide ions was investigated in order to develop a recycling process of gold using iodine-iodide solutions. In an anodic polarization curve, the current began to rise at an anodic potential of around 0.5 V vs. SHE, and solution near anode surface became brown, which is comparable to the thermodynamic potential for I3−/I− of 0.536 V vs. SHE. In the initial stage of galvanostatic electrolysis, iodine concentration increased with time and iodide concentration decreased. The current efficiencies were more than 90% in this stage. In the further electrolysis, iodine concentration decreased with time and solid state iodine was formed on the anode. The highest concentration of iodine could be estimated by the relationship between its solubility and the initial concentrations of iodine and iodide.
An arsenic removal unit was constructed by the Miyazaki University research group in Bangladesh. The sludge drained from the arsenic removal unit was directed to a sludge tank and allowed to settle down. Then the supernatant in the tank was released to an artificial pond. Biomethylation of arsenic is usually considered as a detoxification of arsenic because toxicity of most organic methylated arsenic is much less than that inorganic arsenic. Microorganisms in the sludge tank were evaluated growth characteristics and arsenic methylation. As a result, dimethylarsinic acid was detected in the broth, and the amount of total arsenic compounds in the broth decreased. It is thought that this loss was contributed by biogenic activity induced by inorganic arsenic biomethylation to gasified volatile organic species, such as monomethylarsine and dimethylarsine. These results suggested that microorganisms in the sludge tank may be utilized for natural attenuation of arsenic sludge from the arsenic removal unit.