Characterization of Wastewaters and Sludges
where fsi,N fxi,N and fxs,N typically are 0.04-0.08. The concentration of dissolved
inert nitrogen, SN,r. may vary considerably (1-4 g N/m 3 ) in ordinary municipal
wastewater and may therefore sometimes cause problems in connection with the
maintenance of low effluent requirements for nitrogen.
Table 2.4 gives typical fractions of nitrogen and phosphorus in organic matter in
municipal wastewater.
Symbol
Component
Typical range
N
p
Ss
Readily (fermentable) biodegradable substrate
2-4
1-1.5
SA
Volatile acids (acetate)
0
0
s,
Inert, non-biodegradeable organics
1-2
0.2-0.8
x,
Inert, non-biodegradeable organics
0.5-1
0.5-1
Xs
Slowly biodegradeable substrate
2-4
1-1.5
XH
Heterotrophic biomass
5-7
1-2
XrAo
Phosphorus-accumulating organisms
5-7
1-2
XrHA
Stored poly-hydroxy-alkanoate
0
0
XA
Autotrophic, nitrif~in_g biomass
5-7
1-2
Table 2.4
Fractions of nitrogen and phosphorus in organic matter in municipal wastewater (g/ g COD) /20/
2.4. Phosphorus
Phosphorus in wastewaters may be divided into the following fractions:
CTP = Spo4 + Sp-P + Sorg.P+ Xorg.P
where CTP is total phosphorus,
Spo4 is dissolved inorganic orthophosphate,
Sp-P dissolved inorganic polyphosphate,
Sorg.P is dissolved organic phosphorus,
Xorg.P is suspended organic phosphorus.
(2.12)
Normally a more detailed division of phosphorus will not be necessary An analysis
of these fractions is performed by using the well-known laboratory methods.
2.5. Alkalinity (TAL)
The alkalinity of the wastewater is important for its ability to resist acid/base
influences. The alkalinity is measured by conventional titration with acid to an end
pH of 4.5. The higher value, the greater buffering capacity.
Different processes for the treatment of wastewater change the alkalinity, this
applies to nitrification, denitrification and chemical precipitation. Normally muni49