Cadmium Removal from Scallop Mid-Gut Gland Wastes by Dilute Sufuric Acid Leaching and Electrowinning Processes

摘要

In order to recycle the organic waste of scallop mid-gut gland as fertilizer and fish meal, a novel removal process of cadmium contained in scallop mid-gut gland has been developed by using both dilute sulfuric acid leaching and electrowinning. In this investigation, cadmium removal degree from scallop mid-gut gland was examined under various leaching and electrowinning conditions. The experimental results obtained are summarized as follows: 1) In advance, sample of scallop mid-gut gland waste was treated to eliminate greasy component because a cathode electrode plate in an electrowinning process was partially covered by the greasy component. 2) The cadmium removal degrees by this process gave the high values from 97 percent to 98 percent for leaching time of 3 hours and electrowinning time of 5 hours under the following optimum conditions: sulfuric acid concentration is 0.54 mol/l or 0.9 mol/l, temperature 40 deg C or 60 deg C and electrowinning voltage 3.8V or 4.6V 3) The cadmium concentration of scallop mid-gut gland waste was reduced to 5 ppm or less (based on dry weight) by this process, and scallop mid-gut gland waste was utilized as fertilizer and fish meal. 4) A novel removal process of cadmium contained in scallop mid-gut gland waste was shown as a flow chart. 5) In this process, cadmium deposits recovered on the cathode electrode plate during the electrowinning may be recycled as mineral resources.