| IC reactor is one of the representatives of third-generation anaerobic reactor, applying in dealing with kinds of organic wastewater. Its stability and high-performance depends on the formation of granular sludge with good settlement and high methanogenic activity. Therefore, the anaerobic granular sludge characteristics of the IC reactor have been the focus of research. This experiment made use of IC reactor which was self-designed and inoculated the sludge from the concentration tank in a sewage treatment plant. The main purpose of the study was to see the cultivation of granular sludge and the change of characteristics of sludge in start-up phase of the IC reactor, the phase of treatment of regenerated papermaking wastewater at normal temperature. As well as the inhibition and inhibitory mechanism of Di-n-butyl phthalate (DBP) which is typical pollutants and wildly distribution in the regenerated papermaking wastewater was observed.in intermittent experiment. The results showed that:In the start-up, the volume loading rate of IC reactor increased from 3.0kgCOD/m3·d to 14.4kgCOD/m3·d, HRT was 24.0h to 4.8h, gas product was 4.5L/d to 45.1L/d. After the reactor ran steadily, the COD removal efficiency was above 90%, thus the start-up of IC reactor was finished. Sludge concentration kept about 66g/L, the VSS and the VSS/SS was increased gradually; the rate of the granular sludge which size was less than 0.3mm decreased to 39.4%, and which size between 0.9 and 2.0mm was up to 17.8%, and which was more than 2.0mm reached 6.6%; The sedimentation rate was 34.05～109.75m/h, which has a good settling performance. In 25 days, granular sludge can be found in the reactor; 70 days after, the completion of sludge granulation indicates that granular sludge cultured using flocculent sludge at room temperature is feasible. After the start-up of reactor had been finished, SEM phtograph of anaerobic granular sludge showed that it was rugged and some holes of different shapes existed on the surface. Moreover, filamentous bacteria and Methanobacterium was major in microorganisms of anaerobic granular sludge.In the treatment process of regenerated papermaking wastewater with IC anaerobic reactor, anaerobic granular sludge was domesticated first using influent modes of syntheticglucose wasterwater and regenerated papermaking wastewater. After 20 days of operation, the granular sludge acclimation completed. After acclimation, the colour of sludge was from yellow to black and gray. The big granular's shape was oval, and the small granular's shape was round. In the domestication phase, the quantity of sludge was changed, SS was 64.5g/L to 66.5g/L, VSS was 48.2g/L to 44.7g/L, and VSS/SS was 72.8% to 67.2%; The quantity of sludge which size less than 0.3mm was reduced obviously, it was 32.4%; which size between 0.9 and 2.0mm was increased obviously, it was 26.5%; The sedimentation rate was reduced, it was 23.02～92.34m/h. Methane production rate reached the best within 10 hour, so the Methanogenic activity of granular sludge was best when the HRT was low. In the steady running phase, SS was 66.5g/L to 75.2g/L, VSS was 44.7g/L to 55.2g/L, and VSS/SS was 67.2% to 73.7%. The main size of the granular sludge was reduced. Which size less than 0.3mm was increased obviously, it was 41.7%. And which size was 0.9 to 2.0mm was reduced obviously, it was 21.9%. The sedimentation rate fluctuated, it has an extremum. When HRT was 5.5h, the content of EPS was the largest, and the degree of granulation was high. Coenzyme was reduced when HRT was reduced; the final value was 0.09umol/g.In the biological toxicity experiments, the inbition of biological activity to anaerobic granular sludge all existed at the concentrations of 0.16g/L,0.31g/L,0.52g/L,0.84g/L,1.04g/L and 1.57g/L. And with increasing concentrations of DBP, the inbition increased. Methanogenic activity resuming test indicates that the toxicity of DBP is metabolic in lower concentrations (≤0.16g/L) but physiological when the concentration is increased (0.31～1.04g/L) and it is bactericidal toxicity the concentrations of DBP bigger than 1.57g/L. Along with the DBP concentrations increasing, polysaccharide and the protein in anaerobic granular sludge decreased gradually. For the extracellular polymeric substances (EPS), the protein content is higher; the ratio of protein and polysaccharide is between 1.66 and 2.78. When the DBP concentration reached to 3.14g/L, the proportion of protein and polysaccharide decreased to 1.66, while for the contrast sample, the proportion come to maximum. With the increase of DBP concentration, specific methanogenic activity of granular sludge and coenzyme F420 content all decreased, and they showed the same trend to change.
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