铝盐、铁盐对侧流磷回收及生物除磷性能的影响

Effect of aluminum and ferric salts on the recovery of phosphorus in sidestream stripping process and the performance of biological phosphorus removal

摘要:

为研究铝盐、铁盐对厌氧释磷上清液中的磷进行化学回收潜能及对主流系统生物除磷性能造成的影响,设计两组平行运行的SBR反应器,分别以铝盐、铁盐作为侧流除磷药剂,对出水指标、污泥性能和磷回收情况进行分析.结果表明,两个系统的厌氧最大释磷率可以分别达到进水磷量的2.58倍与2.63倍,铝盐与铁盐在一个运行周期平均分别可以回收1.57倍、2.68倍的进水磷资源.整个实验过程中两个系统的COD去除效果均没有发生明显的变化.而由于侧流操作不断剥夺主流系统的磷,导致PAOs的胞内聚磷颗粒合成减少,厌氧释磷率下降,系统生物除磷性能受到抑制.因此,在停止磷的剥夺后,两个系统对TP去除率均明显下降.但由于铝盐对主流系统磷的剥离量较铁盐少,铝盐系统能快速恢复,而铁盐系统所需时间较长.侧流过程中,返回上清液中存在的少量Al³⁺、Fe³⁺促使两个系统的胞外聚合物质量分数均有明显增加,铝盐系统的胞外聚合物（EPS）质量分数相对侧流之前增加了62.93%,铁盐系统的胞外聚合物增加了94.52%.综上铝盐系统所受的影响较铁盐系统小,磷回收量少,但可以在较短的时间恢复并进行下一次侧流操作,最大化磷资源回收利用,降低时间成本.

Abstract:

The study investigated the recovery potential of phosphorus from supernatant enriched with phosphorus by aluminum and ferric salts, as well as the effects on the performance of mainstream biological phosphorus systems. Two parallel SBR reactors were designed, which used aluminum and ferric salts as flocculants to illustrate the influence on the performances of wastewater treatment, sludge, and phosphorus recovery. Results indicated that the maximum release rates of phosphorus in anaerobic stage of the two systems could be 2.58 and 2.63 times of the influent phosphorus, and the average recovery contents of the influent phosphorus resources by aluminum and ferric salts in a cycle were 1.57 times and 2.68 times. In addition, the COD removal efficiency was not significantly affected by the stripping treatment. Due to the stripping operation, the intracellular polyphosphate particle content in PAOs decreased, the ability of phosphorus release declined, and the phosphorus removal by microorganism was inhibited. Therefore, the removal rates of phosphorus in the two systems declined after stopping sidestream stripping. Owing to the lower removal rate, the aluminum salt system could be recovered in a shorter time, while the ferric salt need a longer time. In sidestream stripping period, a little residue of Al³⁺ and Fe³⁺ promoted the increase of extracellular polymeric substances produced by microorganism. The contents of EPS in the aluminum salt system and the ferric salt system increased by 62.93% and 94.52%, respectively. In summary, though the content of phosphorus recovery in aluminum salt system was smaller than that of the ferric salt system, the restoration capability was stronger, and the effect on the ability of biological phosphorus removal in mainstream system was less, which were more beneficial for the long-term recovery of phosphorus.