Anaerobic fluidized bed reactor has better mass transfer
characteristics when compared with the fixed biofilm reactor.
Additionally, AFBR has high amount of attached biomass which
is rich in microbial diversity and it recoveries rapidly after instability
conditions changed [80,85]. Reported operational conditions
and performance comparisons of AFBRs for the treatment of dairy
wastewater are given in Table 3. Toldra et al.[86] studied the effects
of temperature and HRT on the treatment of low-strength dairy
wastewater (0.2–0.5 g COD L−1) in an AFBR. They reported that
reducing temperature from 35 ◦C to 20 ◦C decreased COD removal
efficiency between 10 and 25%; however, the reactor performance
gradually increased with the increasing of HRT from 0.083 to
0.33 d. Borja and Banks [23] changed pH, temperature and OLR
and monitored the AFBR performance for the treatment of icecream
wastewater at constant HRT of 0.33 d. Increasing of organic
loading by stepwise increment ofinfluentCOD concentrationshortened
start-up duration while changes in operational parameters
decreased pH and alkalinity. Reduction in pH decreased removal of
suspended solids and COD, and biogas production; however, reactor
recovered within 0.25–0.67 d upon restoring normal conditions.
The reactor achieved the highest COD removal of 94.4% at OLR of
15.6 kg COD m−3 d−1.