Specific methanogenic activity test
The inhibition threshold of NH4 + –N concentration on anaerobic
granular sludge was determined by static test, based on specific
methanogenic activity (SMA). The anaerobic granular sludge came
from the EGSB reactor at the end of period 1. SMA of the sludge was
measured in triplicate in 125 mL serum bottles, each with a total
liquid volume of 100 mL at 33 C under strict anaerobic conditions,
following the procedure suggested by (Kettunen et al., 1996). An
acetic acid solution (4.5 g COD/L) was used as the medium by
adjusting pH to 7.0–7.2 by 1 mol/L NaOH. The sludge was divided