| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Tetsuhito Tokyo University of Marine Science and Technology, Faculty of Marine Science, Professor, 海洋科学部, 教授 (00173013)
GOTO Sumio National Institute for Environmental Studies, Lab of Recycling Technology System., Head., 循環技術システム研究開発室, 室長 (30112890)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Research Abstract |
We tried to develop the treatment system for an industrial waste from sea scallop processing factory. The major purposes of this study are as follows. 1) to reduce the load to environment, 2) need a small facility investment, 3) recycled bio-resource can be used for organic farming, and 4) removed Cd must be safe for final disposal.
1.Weak acid washing: Upon addition of a weak acid solution of water (as a control) for the same volume, Hepatopancreases (abbreviated as HP) one kilogram were crushed and heated in a boiling water bath. After the temperature of the central part of the mixture had reached to 80 degree C in the bath, then the mixture was kept stirred for another ten minutes. This treatment was repeated three more times and the concentration of washed HP was decreased gradually and it became below than legal allowable maximum level (1 ppm). As remaining nitrogen in washed HP was higher in that treated with acetic acid, this weak acid was thought to be preferable for biological
… More
resource utilization.
2.Final treatment of washing solution: Since the volume of the combined washing solutions was more than five times that of the unwashed HP, it was difficult to discard the solution without additional treatment. After all washings were combined and concentrated, Na2S was added to produce cadmium sulfide for reducing the solubility of the heavy metal. After addition of PAC for coagulation, the combined washing solutions were centrifuged. The concentration of Cd in the supernatant was 0.55ppm, about one thirtieth of that of starting material (18 ppm; squeezed liquid of untreated HP) and total nitrogen was 0.72%. On the other hand, Cd concentration of coagulated precipitate was 288 ppm as an anhydride.
3.Final treatment of coagulated precipitate occurred in concentrated washing solution: Fixing reagent Meta-seal, supplied by Telnite Co., was added to the precipitate, after the moisture of which was adjusted to 58%, at the ratio of 0, 2.5, or 5.0%, and then mixed well. The homogenate was left in an open air for three days. Cd elution from cemented precipitates was determined to be 0.14(5%)~ 0.21mg/L(2.5%) and satisfied the environmental standard (0.3mg/L).
Remaining Cd in the final disposal also met the requirement for organic fertilizer. Except for glycine and taurine, amino acid loss by washing was relatively low. Cd level in the final disposal met the environmental standard and was able to dump directly to final landfil site. Less
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