It can be seen that the particulate fraction of the tot n was around 20%, and that the filtered Tot N was about equal to the inorganic N. Consequently the organic n was mainly on particulate form This can also be seen from the fact that the amount of n left after coagulation was very close to the sum of the inorganic N In table 3 the results of the survey of the Scandinavian plants are shown with respect to nitrogen as well as phosphorus Table 3 Average values on N and p in raw wastewater from Scandianvian plants Country N TotN NH -N F-Nss Tot P PO -P F-Pss Sweden 1733,124,4 0, 6.14 8.1+7.6 +0.13 +165+142 +0.15 12 0 13.7 0,29 3.00 1.10 0.65 +4.2 +0.08+1.12+0.62+0.09 Finland 743828,7 0.33 7.473.29 +10.4+7.6 +007 +134 Based on the assumption that the organic n is suspended 2 Based on the assumption that the soluble p is equal to soluble PO4-p As it is shown i figure 4, the suspended fraction of tot n varies between 0, 2 and 0, 5, but is in most cases around 30 % It seems to decrease a bit with increasing tot N concentration. Generally it seems from the data that the plants with a higher fraction of soluble COd had a lower fraction of particulate N. This seems reasonable, since the particulate n to a large extent is organically N bound in biomass In oxygen- rich systems with considerable biodegradation, inorganic, soluble N(NH4-N is used in the assimilation process producing biomass, i. e particulate, organic N 日0.8 ay 08 0.6 ▲ Finland 0.6 0.4 o Swede ▲ Finland 0 0102030405060 2 6 Total N, mg N/ Total P, mgP/ igure 4 Fraction of N and P on suspended form In the survey, some plant owners gave data for filtered tot P and some only on PO4-P. The difference was not great. However, filtered tot P is on average somewhat higher than PO4-P. There were large variations from plant to plant with respect to the particulate fraction of phosphorous(30 80%). This may be caused by the fact that the sludge water may influence in some cases on inlet concentrations since the inlet sampling point in some cases may be downstream the introduction point of the sludge water. It was a bit surprising, however, that in most of the plants the fraction of particulate P was higher than 50 %. Again, it is the plants with a low fraction of soluble COD, that has a high fraction of particulate P. As mentioned for nitrogen, this indicates again that a considerable fraction of the particulate P is in fact present in biomass6 It can be seen that the particulate fraction of the tot N was around 20 %, and that the filtered Tot N was about equal to the inorganic N. Consequently the organic N was mainly on particulate form. This can also be seen from the fact that the amount of N left after coagulation was very close to the sum of the inorganic N. In table 3 the results of the survey of the Scandinavian plants are shown with respect to nitrogen as well as phosphorus. Table 3 Average values on N and P in raw wastewater from Scandianvian plants Country N Tot N NH4-N F-NSS 1 Tot P PO4-P F-PSS 2 Sweden 17 33,1 +8,1 24,4 +7,6 0,28 +0,13 6,14 +1,65 3,26 +1,42 0,49 +0,15 Norway 12 22,0 +6,2 13,7 +4,2 0,29 +0,08 3,00 +1,12 1,10 +0,62 0,65 +0,09 Finland 7 43,8 +10,4 28,7 +7,6 0,33 +0,07 7,47 +1,34 3,29 +1,36 0,56 +0,19 1 Based on the assumption that the organic N is suspended 2 Based on the assumption that the soluble P is equal to soluble PO4-P As it is shown i figure 4, the suspended fraction of tot N varies between 0,2 and 0,5, but is in most cases around 30 %. It seems to decrease a bit with increasing tot N concentration. Generally it seems from the data that the plants with a higher fraction of soluble COD had a lower fraction of particulate N. This seems reasonable, since the particulate N to a large extent is organically N bound in biomass. In oxygen-rich systems with considerable biodegradation, inorganic, soluble N (NH4-N) is used in the assimilation process producing biomass, i.e. particulate, organic N. Figure 4 Fraction of N and P on suspended form 0 0,2 0,4 0,6 0,8 1 02468 1 Total P, mgP/l Fr a ction s u s p e nded P Sw eden Norw ay Finland 0 0 0,2 0,4 0,6 0,8 1 0 10 20 30 40 50 60 Total N, mg N/l Fr a ctionsuspended N Sw eden Norw ay Finland In the survey, some plant owners gave data for filtered tot P and some only on PO4-P. The difference was not great. However, filtered tot P is on average somewhat higher than PO4-P. There were large variations from plant to plant with respect to the particulate fraction of phosphorous (30- 80 %). This may be caused by the fact that the sludge water may influence in some cases on inlet concentrations since the inlet sampling point in some cases may be downstream the introduction point of the sludge water. It was a bit surprising, however, that in most of the plants the fraction of particulate P was higher than 50 %. Again, it is the plants with a low fraction of soluble COD, that has a high fraction of particulate P. As mentioned for nitrogen, this indicates again that a considerable fraction of the particulate P is in fact present in biomass