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In this study, a lab-scale bioreactor of upflow anaerobic sludge blanket (UASB) was operated to treat purified terephthalic acid (PTA) manufacturing wastewater. We considered that the wasted biological sludge produced by aerobic activated sludge unit needed additional treatment and disposal. Therefore, the UASB bioreactor was fed with the PTA wastewater and a limited quantity of the wasted biological sludge, or associated with a limited quantity of alkalified wasted sludge. The influence of two different supplemented sludge on the PTA wastewater treatment was investigated as the following results:1. The one-year acclimated anaerobic sludge was inoculated into the lab-scale UASB. The PTA wastewater associated with the wasted activated sludge at 20% of COD proportion were fed into the UASB. Then, the UASB process was operated with different HRT(5days,4days and 3days)and low organic loading. Beside the second run, the removal efficiency of COD achieved above 70%. The removal efficiency of the less degradable TA (terephthalic acid) also achieved to 75% and more. The result revealed that the supplement of wasted biological sludge had no obvious influence on the treatment efficiency of PTA wastewater, but sludge accumulation in the UASB reactor is very obvious.2. On the other hand, the activated sludge was hydrolyzed with Sodium hydroxide. The longer hydrolysis obtained the higher sludge hydrolysis rate, while the higher pH obtained the higher hydrolysis rate. However, the higher pH consumed more caustic Chemical.3. In the run of the PTA wastewater feeding with the alkalified biological sludge(pH=12,and 12hr of hydrolysis),the UASB process was operated also with the different HRT (5days, 4days and 3days) and low organic loading. The removal efficiency of COD achieved above 80% with no matter of long HRT. The removal efficiency of TA (terephthalic acid) achieved to 90% and more. The removal efficiency of the refractory p-Tol (para-toluic acid) even achieved to 95% and more. Eventually, TA and p-Tol were removed completely at the final experimental period. The result revealed that the alkalified biological sludge enhanced the treatment efficiency of the PTA wastewater with better process performance. The granulated sludge in UASB achieved to 0.7mm×0.5mm of the particle size.4. Comparative biodegradation of the supplemented hydrolyzed sludge in batch test. It revealed that sludge hydrolyzed liquid had no obvious removal effect. Biogas transfer rate attended to 0.3L biogas/gCODr from the influent substrate.5. The microbial observation of anaerobic sludge using the scanning electronic microscope(SEM) indicated that the obvious bacteria included different rods-like bacteria and sarcina, the anaerobic sludge were already composed with network of extra-cellular materials and various anaerobic bacteria that were juxtaposed together with syntrophic structure.
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