Influence of sludge retention time on tolerance of copper toxicity for polyphosphate accumulating organisms linked to polyhydroxyalkanoates metabolism and phosphate removal

► We found SRT is an effective method for controlling the toxic effect in EBPR. ► We find the copper inhibition at 10d SRT sludge was higher than that at 5d SRT. ► PHA storage at 10d SRT sludge was less influenced by copper invasion. ► DNPAOs had a higher SPUR at 15d SRT, but non-DNPAOs had a higher SPUR at 10d SRT. ► PHAs degradations for both DNPAOs and non-DNPAOs are sensitive to copper invasion.