Table 1.

Sludge characteristics and some basic parameters of the waste water treatment plant in Zirl, Austria

Parameter
Mode of digestion	Cosubstrate digestion
Reactor capacity (population equivalents)	61 500
Electrical conductivity [mS cm−1]	10.1
pH	7.9
Specific weight (38°C)	0.972 ± 0.004 kg/L
Osmotic strength [mOsmol L−1]	177
TS [g 100 g−1 fresh weight]	3.1
VS [g 100 g−1 total solids]	61.0
Alkalinity (pH 4.3) [mmol L−1]	100
NH4‐N [mg N L−1]a)	1 385
Phosphate [mg P L−1]b)	34
Proteins [mg L−1]c)	41

performed after:

^a 22.

^b 23.

^c 24.