| With the development of social economy and the acceleration of urbanization, the problems of phosphorus removal and sludge treatment of wastewater plant were becoming prominent, and these problems may limits the development of social economy. With advantages such as low cost,high efficiency and no secondary pollution, these technologies which using tubificidae predation to reduce excess sludge and enhanced biological phosphorus removal (EBPR) had been recently received increasing attention by some researchers. The symbiotic EBPR system combined excess sludge reduction induced by tubificidae with enhanced biological phosphorus removal was developed creatively. What's more, A series of studies of the symbiotic EBPR system had been systematically carried out, aimed to provide reliable rationale and useful scientific instruction for promoting the effect of phosphorus removal in sludge reduction process based on tubificidae predation.In this study, excretion and debris of tubificidae were chosen to research nutrient release, respectively. Results showed that the cumulitive release amount of TN and TP from the excretion of tubificidae were0.11mg·g-1and0.068mg·g-1respectively, the cumulative release amount of TN and TP from the debris of tubificidae were0.65mg·g-1and0.062mg·g-1respectively. In symbiotic system consisting of tubificidae and microbes, the amount of excretion of tubificidae was much more than the debris of tubificidae, thus, the debris of tubificidae was less influence on the symbiotic system than the excretion of tubificidae. Effect of phosphorus removal influenced by excretion of tubificidae was carried out for30d, results showed that excretion of tubificidae as a kind of complex organic matter, can promote phosphorus removal of EBPR system. The amount of phosphorus removal in test group was11.64mg·L-1, slightly more than the control group, which was10.96mg·L-1.Based on above researchs, symbiotic EBPR systems consisting of tubificidae and microbes were established and operated for120d. Results showed that tubificidae can growth well in anaerobic-aerobic alternate operation environment, after the system was in the steady state of running, the tubificidae maintain at4.4+0.6g per unit padding. The apparent sludge yield coefficient of symbiotic EBPR system was0.184gMLSS/gCOD, which was decreased by25.2%when tubificidae predation. Moreover, phosphorus release with PO43-P concentration in the anaerobic effluent was15mg·L-1higher than the conventional EBPR system. The storaged substance of PHAs compound in anaerobic process was mainly PHB, with a small amount of PHV, the compound PHB and PHV of symbiotic EBPR system were much more than the conventional EBPR system. The PO43--P removal of symbiotic EBPR system was increased obviously from86.6%to94.3%, thus, the PO43--P concentration of effluent maintain lower than0.5mg·L-1.Analysis by PCR-DGGE shows that the diversity of microorganisms were really high after symbiotic EBPR system established. Compared with conventional EBPR system, the structural similarity of microbial colonies was low. In symbiotic EBPR system, PAOs including Pseudomonas sp, Uncultured Rhodocyclaceae bacterium, Thiothrix sp, Thiothrix nivea, Sulfur-oxidizing bacterium and Candidatus Competibacter phosphatis, a type of GAOs were the dominate microbes. Compared with conventional EBPR system, Pseudomonas sp, Uncultured Rhodocyclaceae bacterium, Thiothrix sp were appeared, while some Candidatus Competibacter phosphatis was disappeared. |
