Abstract
In this study, the influence of azo dye of methyl red (MR) on COD, dye and phosphorus removal and the transformation of polyhydroxyalkanoate (PHA) and glycogen of phosphate accumulating organisms in enhanced biological phosphorus removal (EBPR) system were investigated. The results indicated COD and dye removal efficiencies were decreased from 97.9% to 72.8% and 99.7% to 82.0%, respectively, when MR concentration was increased from 0 to 40 mg/L. Low MR concentration (5 mg/L) had no influence on P removal and transformation of PHA and glycogen. However, P removal, PHA production and consumption, and glycogen replenishment were seriously inhibited at high MR concentration, while glycogen hydrolysis was simulated at MR concentration of 20 and 40 mg/L. The transformations of PHA and glycogen at aerobic condition were more sensitive to those at anaerobic condition at high MR concentration. These results demonstrated dye and its intermediate products would inhibit the metabolism of polyphosphate accumulating organisms, which should be taken into account in future work.
Highlights
IntroductionIn this process, activated sludge was under the alternating anaerobic and aerobic conditions and polyphosphate accumulating organisms (PAOs) could be enriched in this system
The pollution removal and transformation of PHA and glycogen at different methyl red (MR) concentrations in enhanced biological phosphorus removal (EBPR) system were investigated in this study
The chemical oxygen demand (COD), dye and phosphorus removal efficiencies were all decreased with the increase of MR concentration
Summary
In this process, activated sludge was under the alternating anaerobic and aerobic conditions and polyphosphate accumulating organisms (PAOs) could be enriched in this system. Under anaerobic conditions, PAOs take up volatile fatty acids and store them to intracellular polyhydroxyalkanotes (PHAs), with the energy obtained from glycogen utilization and poly-phosphate (poly-P) hydrolysis and simultaneously released of ortho-phosphorus into solution. Under aerobic conditions, PAOs take up excess phosphorus as intracellular poly-P formation and simultaneously glycogen is replenished by the oxidation of stored PHA. With wasted activated sludge enriched in poly-P discharging, the net removal of phosphorus in activated sludge can be achieved [1]
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