This paper used ââ?¬Ë?ultrasonic lysis-cryptic growthââ?¬â?¢ in SBR to analyze the accumulation and chemical fraction distribution\nchanges of cadmium and lead in sludge. Results showed that ââ?¬Ë?ultrasonic lysis-cryptic growthââ?¬â?¢ technique cut sludge\nproduction by around 50%. Accumulation of cadmium and lead in sludge occurred in SBRs, and had light impacts on the\nperformance of bioreactors. The accumulation of cadmium was higher than that of lead. The co-existence of cadmium and\nlead in influent affected the accumulation of each other in sludge. Cadmium content in sludge first increased and decreased\nfinally. During 30-60 daysââ?¬â?¢ operation, the cadmium content in sludge of ââ?¬Ë?ultrasonic lysis-cryptic growthââ?¬â?¢ system was 56\ntimes more than the initial content in the seed sludge. Lead content change in sludge during 90 daysââ?¬â?¢ operation was just\nopposite to that of cadmium. After 30-60 daysââ?¬â?¢ operation, the Lead content in sludge decreased by 40%, comparing with the\ncontent after the first 30 daysââ?¬â?¢ operation. Chemical fraction distributions of both heavy metals changed with different\noperational durations. The exchangeable fraction of cadmium increased during 90 daysââ?¬â?¢ operation in control system;\nhowever, the changes were irregular in ââ?¬Ë?ultrasonic lysis-cryptic growthââ?¬â?¢ system. Possible reason was that sonication changed\nthe binding sites of sludge for cadmium. The residual fraction of lead was the main form in sludge, and the chemical fraction\ndistributions changed insignificantly in both bioreactors during 90 daysââ?¬â?¢ operation. It might be that lead in influent formed\ninsoluble salt and precipitated in sludge.
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