摘要:Laboratory wastewater contains many kinds and various forms of chemicals, and is discharged discontinuously. Especially, heavy metal wastewater which is released from research, educational and medical facilities of universities often contains organic acids as ligands. The aluminum coprecipitation process is one of the usual methods to remove heavy metals from inorganic wastewater. However, it is interfered with the organic acids contained in the wastewater. The wastewater was examined by a semibatch treatment system ; the aluminum solution was constantly fed into the vessel filled with wastewater adjusted to pH 7. A zinc solution containing oxalic acid was used as a model wastewater. In this paper, the efficiency of zinc removal was measured at various initial concentrations of zinc and oxalic acid. As a result, it was found that the zinc removal is interfered with such two reasons as forming complexes between aluminum and oxalic acid, and between zinc and oxalic acid. In order to improve efficiency of heavy metal removal, the following methods were discussed ; addition of heavy metal to compete with aluminum in the complex reaction of oxalic acid, or adjustment of the heavy metal concentration to its better removal coefficient. It is found that the laboratory wastewater can be reasonably adapted to such operations.