NITRIFICATION AND ITS SUPPRESSION IN THE BOD TEST
This study is concerned with nitrification in the BOD test and how to suppress it. The results show that a significant proportion of the BOD value of biologically treated municipal effluents is due to nitrification and that it can be suppressed by the addition of allylthiourea (ATU). A national survey comprising 298 samples from 35 municipal treatment plants showed that addition of 2.0 mg/1 of ATU is sufficient to ensure suppression of nitrification in the BOD7 test. There is no indication that nitrification takes place during the BOD determination of biologically treated pulp and paper mill effluents. Nevertheless the addition of ATU is recommended. It does not interfere with the determination, but ensures that only carbonaceous BOD is determined and widens the choice of seed, because any nitrification introduced by the seed will be suppressed. “Complete abstract not presented.”