It should be noted that the SU and CU wastewaters were also rich in ammonia and organic nitrogen (Figs. 2 and 3). The ammonia concentrations were 344 ± 174 mg N–NH4/dm3 in the SU and 1223 ± 443 mg N–NH4/dm3 in the CU. For Norg, its concentration in the SU varied from 8 mg Norg/dm3 to 555 mg Norg/dm3 (av.151 mg Norg/dm3), whereas its concentration in the CU reached up to 2560 Norg/dm3 (extreme value not shown in Fig. 3 for scale reasons), with an average of 364 mg Norg/dm3.