The MIC anaerobic reactor with an external hydraulic circulation
system provided long sludge retention and good hydraulic
conditions, resulting in a good mixing pattern between sludge and
substrates and efficient dyeing wastewater treatment.
The granular sludge was used as the seed sludge rather than flocculent sludge
so as to shorten the start-up period, in addition, the sludge portion
of above 2mm size increased from 77.9% to 85.5%.
The MIC anaerobic
reactor removed more than 75% COD for dyeing wastewater
with organic loading rate (OLR) of 9.6 kg/(m3 d) and
produced biogas of 2.8 L/L d.Noaccumulation of VFA was observed while the MIC
reactor was operated.
The MIC reactor with an external circulation
system could increase the COD removal efficiency by 14.6% with
respect to the IC reactor.
The suitable upflow velocity of 23.9 m/h
was conducive to excellent mixing of sludge and substrates, resulting
in high COD removal efficiency, but excessive upflow velocity
would cause the granular sludge disintegration and a decline in COD
removal rate. Application of the modified Stover–Kincannon model
for kinetic analysis of the MIC reactor treating dyeing wastewater
revealed a maximum removal rate constant (Umax) and saturation
value constant (KB) of 31.25 g/L d and 34.94 g/L d, respectively, with