Some results of the plant-effluents from chlorine pulp bleaching mills showed the total TEQs are less than the effluent standard : the permissible limit for specified facilities (10 pg-TEQ/L), but more than the environmental standard for public water (1 pg-TEQ/L). The TEQs of 1, 2, 3, 6, 7, 8-and 1, 2, 3, 7, 8, 9-HxCDD are partly responsible for surpassing it. The origin of the HxCDDs in the effluents is thought to be the TeCDD in an agrochemical, but not to be lignin.
In Japan, CNP (chloronitrofen : an agrochemical made from chlorinated phenols) had been scattered in paddy fields as a herbicide. It has been clarified that CNP includes 1, 3, 6, 8-TeCDD, 1, 3, 7, 9-TeCDD and 2, 4, 6, 8-TeCDF. It was found in some results of analysis that concentrations of 1, 3, 6, 8-and 1, 3, 7, 9-TeCDDs in effluents from kraft pulp bleaching plants are relatively high, for example, 100 pg/L for 1, 3, 6, 8-TeCDD. The toxicity equivalency factors (TEFs) for 1, 3, 6, 8-and 1, 3, 7, 9-TeCDD are not defined yet by WHO
1998, and then their concentrations do not consist of the total toxicity equivalency quantity (Total TEQ). However, the TEFs for 1, 2, 3, 6, 7, 8-and 1, 2, 3, 7, 8, 9-HxCDDs are defined as 0. 1. Therefore, the total TEQ of the effluent may increase if the HxCDDs form from the TeCDDs by chlorination.
Some results of the plant-effluents from ECF (chlorine dioxide) pulp bleaching mills showed the total TEQs are lower than the environmental standard (1 pg-TEQ/L). It was found in some results of analysis that concentrations of 1, 3, 6, 8-and 1, 3, 7, 9-TeCDDs in effluents from kraft ECF pulp beaching plants are relatively high, for example, 440 pg/L for 1, 3, 6, 8-TeCDD, which should be impurities in the CNP. Laboratory bleaching using a mill LOKP and chlorine dioxide in the range of KF : 0. 14-KF : 1. 14 have shown that 2, 3, 7, 8-TeCDD and TeCDF are not detected. It is considered that water qualities of process sewers in ECF pulp bleaching mills should be less than the environmental water quality (1 pg-TEQ/L).
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