中文摘要：

以西安市某再生水厂的出水为对象，首先通过静态试验研究了再生水中余氯与异养菌数的消长关系，然后通过测定再生水中碳、磷浓度评价了其生物稳定性，并在此基础上采用生物可利用磷（MAP）阈值法和细菌再生长潜力法探索了碳、磷对再生水中细菌再生长的限制影响。结果表明：即使保持1．35mg／L的余氯浓度，再生水依然会发生细菌再生长问题，且当停留时间〉36h后，异养菌按对数增殖；再生水的可同化有机碳（AOC）、生物可降解溶解性有机碳（BDOC）及MAPmax均值分别为454．61μg／L、1．67mg／L和13．81μg／L，其生物稳定性较差；在碳、磷浓度均超过生物稳定性限值条件下，该再生水中细菌再生长的限制因子为有机碳。

英文摘要：

A static test was carried out to investigate the relationship of residual chlorine to in- crease and decrease the number of heterotrophic bacteria in the effluent from a wastewater treatment and reuse plant （WTRP） in Xi＇ an. The concentrations of carbon and phosphorus were measured to evaluate the biostability of the reclaimed water. Based on the above findings, microbial available phosphorus （MAP） threshold and bacterial regrowth potential （BRP） method were adopted to explore the factors lim- iting the regrowth of the bacteria in the reclaimed water. The results showed that the bacteria could still survive and regrow in the reclaimed water even if the residual chlorine concentration was maintained at 1.35 mg/L. Moreover, the heterotrophic bacteria proliferated by logarithmic relationship when the reten- tion time of the reclaimed water was more than 36 h. The average concentrations of assimilable organic carbon （AOC）, biodegradable dissolved organic carbon （BDOC） and MAPmax in the reclaimed water were 454.61 μg/L, 1.67 mg/L and 13.81 μg/L, respectively, indicating a poor biostability of the re- claimed water. The organic carbon was the major factor to restrict the regrowth of the bacteria in the re-claimed water although both carbon and phosphorus exceeded the limit value of water biostability in this experiment.