双污泥反硝化除磷-诱导磷结晶工艺中污泥的衰减特征

Decay characteristics of activated sludge in a two-sludge denitrifying phosphorus removal process

为调查双污泥反硝化除磷-诱导磷结晶工艺中硝化污泥和除磷污泥的衰减特征,测定硝化细菌耗氧速率(OUR)、聚磷菌PO43--P释放速率(PRR),并利用荧光原位杂交(FISH)技术和DAPI染色方法探究污泥衰减前后目标微生物的分布。研究结果表明:亚硝酸盐氧化细菌(NOB)7 d平均衰减速率为0.41 d-1,呈指数形式衰减,其衰减过程受综合因素影响;而氨氧化细菌(AOB)7 d平均衰减速率为0.13 d-1,呈线性衰减,其衰减过程仅受外源物质影响。在饥饿状态下,聚磷菌(PAO)可通过分解体内贮存的胞内聚合物而获得能量,其衰减速率较低,7 d平均衰减速率为0.11 d-1,且呈线性衰减。污泥中的目标微生物多以团聚体形式存在,且荧光强度与团聚体内微生物数量有关,污泥经过衰减之后,荧光强度弱的团聚体将消失。此外,与单污泥脱氮除磷工艺相比,采用双污泥脱氮除磷工艺有助于硝化细菌和聚磷菌的富集,且通过延长污泥停留时间(SRT)可选择出耐饥饿状态下的目标微生物。

The decay characteristics of nitrification sludge and denitrifying phosphorus removal sludge in a two-sludge denitrifying phosphorus removal process were investigated by using the analysis of oxygen uptake rate （OUR） and phosphate release rate （PRR）, and the distribution of targeted-microorganisms within sludge during the decay process was also investigated by fluorescence in situ hybridization （FISH） and DAPI staining. It is found that the averaged decay rate of nitrite-oxidizing bacteria （NOB） for 7 d is 0.41 d-1, showing an exponential relationship between OUR and time, which is affected by comprehensive factors. However, the averaged decay rate of ammonia-oxidizing bacteria （AOB）, 0.13 d-1, is lower than that of NOB. A linear relationship is hold between OUR and time, suggesting that the decay characteristics of AOB is only affected by the lack of nutrient substances. In this process, the decay rate of polyphosphate-accumulating organisms （PAO） is 0.11 d-1, also showing a linear relationship between PRR and time. The targeted-microorganisms in sludge preferably grow the dense clusters, and fluorescence intensities of the clusters are consistent with the abundance of targeted-microorganisms. A cluster containing lower fluorescence intensity can more easily contribute to the bacterial death during the decay period. Moreover, compared with single-sludge wastewater treatment systems functioning as nitrogen and phosphorus removal, two-sludge process proposed here has a great advantage to enrich AOB, NOB and PAO, and the ability of the targeted-microorganisms resistance to hunger can be enhanced with the increase of SRT.